Complement requirement for virus neutralization by antibody and reduced serum complement levels associated with experimental equine herpesvirus 1 infection.

Pony foals, negative for detectable serum-neutralizing antibody to equine herpesvirus 1 by the standard tube-culture virus neutralization test, were experimentally infected with equine herpesvirus 1. Complement-requiring (CR) and non-complement-requiring (NCR) serum-neutralizing antibodies were evaluated in preinfection and postinfection sera by means of a complement-enhanced plaque reduction assay. Low levels of CR antibodies were found in the preinfection sera of only group II ponies. Upon infection, CR antibodies were detected by day 2 postinfection and reached peak titers between 7 and 14 days postinfection in the antisera of all ponies. NCR antibodies were detected later than CR antibodies and at levels approximately 40 to 150 times lower than the latter. CR/NCR ratios indicated that complement requirement was greatest early in the acute stages of disease and that this requirement decreased during the convalescent phase. Fractionation of 1-week and 2-week postinfection antisera of group I ponies indicated the CR antibody activity resided in both the 7S and 19S fractions. Total serum complement levels of the ponies were quantified throughout the infection with an equine anti-goat erythrocyte hemolytic system. In vivo, complement levels were depressed for all ponies during the first 2 weeks of infection. A decline in complement levels was seen as early as day 2, and they decreased to an average of 35% of preinfection levels on day 10 postinfection for all ponies.     

Suppression of antibody response to Leptospira biflexa and Brucella abortus and recovery from immunosuppression after Berenil treatment.

Zebu cattle infected with either Trypanosoma congolense EATRO 1800 or Trypanosoma vivax EATRO 1721 had suppressed humoral immune responses to Leptospira biflexa injected intravenously and to attenuated Brucella abortus injected subcutaneously. T. congolense infections were more suppressive than T. vivax infections. In cattle infected with T. vivax, the suppression of immune responses to both bacterial immunogens was abrogated when the animals were treated with Berenil at the time of antigen administration. In cattle infected with T. congolense, simultaneous Berenil treatment at the time of vaccination abolished the suppression of immune response to L. biflexa, and lessened but did not abrogate the suppression of immune response to B. abortus.     

Kinetics of haemopoietic progenitor cells during a Trypanosoma congolense rechallenge infection in Boran cattle

In a preliminary study, using clonogenic assays, the in vitro kinetics of committed haemopoietic progenitors were monitored during a Trypanosoma congolense rechallenge infection in five trypanosusceptible Boran cattle. Early in the infection (week 2), in the absence of any detectable parasitaemia, a drop in the number of nucleated marrow cells was recorded. This was accompanied by a marked but transient decrease in the levels of the colony-forming units-erythroid (CFU-E) followed by a partial recovery by weeks 3–4 after infection. The burst-forming units-erythroid (BFU-E) and the colony-forming units-granulocyte macrophage (CFU-GM) also significantly decreased between weeks 2 and 4. After a transient rise at weeks 3–5 postinfection, the CFU-GM steadily declined and remained below preinfection levels throughout the infection. The BFU-E remained below preinfection levels until the end of the experiment. The drop in nucleated marrow cells associated with the decreased numbers of CFU-E, BFU-E and CFU-GM was suggestive of a defect at the pluripotential stem cell level early in the infection (week 2). The erythrocyte indices, i.e. mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCHC), were unchanged until week 10 postinfection. Two animals became severely anaemic; one was euthanised at week 8 and one treated at week 9. The three remaining animals developed chronic anaemia with mean packed cell volume (PCV) fluctuating around 18%–19% between weeks 11 and 14. Low parasitaemia levels were recorded during that period. A CFU-E peak above preinfection levels was noted at week 12 and BFU-E appeared in the peripheral blood culture of two animals between weeks 11 and 14. A progressive rise in MCV associated with a gradual decrease in MCHC also characterised that period. A return to near preinfection levels was recorded for the numbers of all three progenitors three weeks after trypanocidal treatment followed by a full recovery five months after treatment. Although ineffective haemopoiesis has been suggested to contribute to the anaemia of bovine trypanosomiasis, this is the first demonstration of a negative effect on erythroid development in cultures of bone marrow of trypanosome-infected cattle.     

Kinetics of haemopoietic progenitor cells during a Trypanosoma congolense rechallenge infection in Boran cattle

In a preliminary study, using clonogenic assays, the in vitro kinetics of committed haemopoietic progenitors were monitored during a Trypanosoma congolense rechallenge infection in five trypanosusceptible Boran cattle. Early in the infection (week 2), in the absence of any detectable parasitaemia, a drop in the number of nucleated marrow cells was recorded. This was accompanied by a marked but transient decrease in the levels of the colony-forming units-erythroid (CFU-E) followed by a partial recovery by weeks 3–4 after infection. The burst-forming units-erythroid (BFU-E) and the colony-forming units-granulocyte macrophage (CFU-GM) also significantly decreased between weeks 2 and 4. After a transient rise at weeks 3–5 postinfection, the CFU-GM steadily declined and remained below preinfection levels throughout the infection. The BFU-E remained below preinfection levels until the end of the experiment. The drop in nucleated marrow cells associated with the decreased numbers of CFU-E, BFU-E and CFU-GM was suggestive of a defect at the pluripotential stem cell level early in the infection (week 2). The erythrocyte indices, i.e. mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCHC), were unchanged until week 10 postinfection. Two animals became severely anaemic; one was euthanised at week 8 and one treated at week 9. The three remaining animals developed chronic anaemia with mean packed cell volume (PCV) fluctuating around 18%–19% between weeks 11 and 14. Low parasitaemia levels were recorded during that period. A CFU-E peak above preinfection levels was noted at week 12 and BFU-E appeared in the peripheral blood culture of two animals between weeks 11 and 14. A progressive rise in MCV associated with a gradual decrease in MCHC also characterised that period. A return to near preinfection levels was recorded for the numbers of all three progenitors three weeks after trypanocidal treatment followed by a full recovery five months after treatment. Although ineffective haemopoiesis has been suggested to contribute to the anaemia of bovine trypanosomiasis, this is the first demonstration of a negative effect on erythroid development in cultures of bone marrow of trypanosome-infected cattle.     

The temporal relationship among anti-parasite immune elements expressed during the early phase of infection of the rat with Trichinella spiralis

Immunological parameters were measured during the first 20 days of infection with Trichinella spiralis in the rat. Expulsion of adult worms was complete by day 15 postinfection. Eosinophil and neutrophil numbers rose in the blood of infected rats above preinfection levels on days 3 and 6, respectively, and remained high to day 20 postinfection. Release of cytokines by Trichinella-antigen-stimulated mesenteric lymph node cells was measured, and a significant elevation in interferon (IFN)-γ release was detected during the early stage of infection. Although initiated later, interleukin (IL)-10 release showed a pattern similar to IFN-γ. Biphasic release of IL-5 was seen with significant elevation above the preinfection level on day 3 and after day 6 postinfection to the end of the study. IL-4 and IL-2 showed biphasic secretion as well, with the level of IL-4 high in the early and middle part of infection, while the level of IL-2 was detectable only at days 2, 3 and 6 postinfection. Serum anti-parasite IgE rose above preinfection levels after day 6 postinfection. Anti-parasite Ig-positive mesenteric lymph node (MLN) cells were evident by day 3 postinfection for IgM, and day 9 postinfection for IgA and total IgG. The number of Ig-positive MLN cells for all antibody classes returned to preinfection levels by day 20 postinfection. Evaluation of the temporal interactions of the key anti-parasite immune components with which the host engages Trichinella shows a complex interplay between Th1 and Th2 helper subsets. Received: 21 January 1999 / Accepted: 18 February 1999     

The role of the bone marrow in bovine trypanotolerance I. Changes in blood and bone marrow inTrypanosoma congolense-infected cattle

This study compared the changes in the bone marrow (BM) of five trypanotolerant N'Dama cattle with those of four trypanosusceptible Boran cattle during trypanosome infection. In the early parasitaemic phase, from 12 to 21 days postinfection (DPI), tsetsetransmitted primaryTrypanosoma congolense IL 1180 infection induced parasitaemia, slight depression in packed cell volume (PCV), marked leucopenia due to lymphocytopenia and eosinopenia, and thrombocytopenia which were of similar intensity in Boran and N'Dama cattle. However, from 28 DPI until the end of the experiment on 112 DPI, the parasitaemia was higher in the Boran than in the N'Dama. Severe anaemia and leucopenia characterised by lymphopenia, neutropenia, eosinopenia and monocytopenia persisted in Boran cattle. In contrast, the PCV values dropped gradually in N'Dama cattle and from 77 DPI recovered slowly to values just below preinfection levels by 112 DPI. The total and differential leucocyte counts of the N'Dama cattle stabilised at approximately two-thirds of preinfection values between 28 and 112 DPI, and were double those of the Boran. Marked thrombocytopenia occurred in both breeds. The anaemia was initially macrocytic hypochromic but terminally became microcytic hypochromic in both breeds. Light and electron microscopic studies of sequential biopsies of the BM of these animals showed that the BM response was the key to these differences between the N'Dama and Boran. The biopsies of the BM of the N'Dama cattle were hypercellular (scored 4.5±1.0 compared to 4.0 for controls) with mild hyperplasia of erythroid cells and mild hypoplasia of myeloid cells from 28 to 112 DPI, endowing the animals with higher haemopoietic potential that enabled them to replace most lost cells. In contrast, the Boran cattle had hypocellular (scored 2.4±1.1) BM biopsies with relative erythroid hyperplasia and myeloid hypoplasia, resulting in low capacity of cell replacement manifested as severe unremitting anaemia and leucopenia. The BM of both breeds showed moderate hyperplasia of cells of the mononuclear phagocyte system. Therefore, this study showed, for the first time, that BM response is a key determinant factor of trypanotolerance as it determines the animal's capability for blood cell regeneration.     

The effect of the antithyroid drug propylthiouracil on the alternative pathway of complement in rats

The effect of propylthiouracil (PTU) on the lytic activity of complement in rat serum was investigated in vivo. Rats (180+/-10 g) were treated daily by gavage with PTU doses of 1-50 mg/200 g body weight for time intervals ranging from 1 to 30 days. Serum classical pathway (CP) and alternative pathway (AP) activities were determined 24 h after the last dose. A single dose of 50 mg/200 g body weight was administered to additional groups and the animals were sacrificed after periods of 1-48 h.The results showed a relatively small reduction ( approximately 30%) in CP activity, evident only in animals treated with 50 mg of PTU for three weeks. However, a clear and opposite effect of PTU, an increase in lytic activity reaching values up to 180% of controls, was observed on AP activity. This effect was seen at all PTU doses used, and occurred within 4 days of treatment with the highest dose. Maximum activity was observed at intermediate intervals, depending on the PTU dose, with a return to control levels occurring after the longer periods of treatment. The lytic activity of serum from animals treated with a single PTU dose of 50 mg/200 g body weight and sacrificed 1-48 h after dosing did not differ from controls. Serum levels of thyroid hormone (triiodo L-thyronine, T3, and thyroxine, T4) were determined in representative groups of treated animals (injected with 5 mg of PTU/200 g body weight/day). These were either undetectable or considerably lower than those of controls. The serum PTU levels of these rats increased for up to 22 days, reaching values of 2-4 microg/ml.PTU is described in the literature as a modulator of both cellular immune responses and antibody production. Upon complement activation fragments of complement components bind to immune complexes and to specific receptors on cells of the immune system. Thus, alteration in AP activity caused by PTU treatment suggests a possible mechanism by which the drug exerts its modulatory effect. Increased complement AP activity might affect events as antigen presentation and hence the onset and course of the immune response.     

Suppression of mouse complement activity by contaminants of technical grade pentachlorophenol

Pentachlorophenol (PCP) is an antimicrobial agent used chiefly for the preservation of wood. Subchronic oral exposure (14 days) to Technical Grade PCP significantly inhibited the functional activity of female B₆C₃F₁ mouse complement when measured in a microtiter hemolytic assay. When evaluated one day following the final exposure the highest administered dose (100 mg/kg) significantly suppressed the Classical complement pathway, the Spontaneous C1 autoactivation pathway, the Alternate pathway and the level of complement component, C3. Reconstitution studies using C5-deficient serum also demonstrated deleterious effects on this complment component. The Classical pathway was the most sensitive to Technical Grade PCP effects. Animals treated with 100 mg/kg Technical Grade PCP had CH 50 levels 30% of vehicle controls. Animals treated for 14 days and allowed a 15 day recovery period had CH 50 values 36% of control and animals which recovered for 30 days had only 52% of the complement activity of control animals. C3 recovery studies also demonstrated continued suppression on days 15 and 30 post-final exposure. Doses of 10 and 30 mg/kg did not produce the marked effects observed with the highest dose; however, a dose-dependent trend was observed for all responses. Animals treated with 100 mg/kg of EC-7, a PCP preparation with reduced amounts of contaminating dioxins and dibenzofurans, did not demonstrate detrimental effects on the complement system.To whom correspondence should be addressed     

The role of the bone marrow in bovine trypanotolerance I. Changes in blood and bone marrow inTrypanosoma congolense-infected cattle

This study compared the changes in the bone marrow (BM) of five trypanotolerant N'Dama cattle with those of four trypanosusceptible Boran cattle during trypanosome infection. In the early parasitaemic phase, from 12 to 21 days postinfection (DPI), tsetsetransmitted primaryTrypanosoma congolense IL 1180 infection induced parasitaemia, slight depression in packed cell volume (PCV), marked leucopenia due to lymphocytopenia and eosinopenia, and thrombocytopenia which were of similar intensity in Boran and N'Dama cattle. However, from 28 DPI until the end of the experiment on 112 DPI, the parasitaemia was higher in the Boran than in the N'Dama. Severe anaemia and leucopenia characterised by lymphopenia, neutropenia, eosinopenia and monocytopenia persisted in Boran cattle. In contrast, the PCV values dropped gradually in N'Dama cattle and from 77 DPI recovered slowly to values just below preinfection levels by 112 DPI. The total and differential leucocyte counts of the N'Dama cattle stabilised at approximately two-thirds of preinfection values between 28 and 112 DPI, and were double those of the Boran. Marked thrombocytopenia occurred in both breeds. The anaemia was initially macrocytic hypochromic but terminally became microcytic hypochromic in both breeds. Light and electron microscopic studies of sequential biopsies of the BM of these animals showed that the BM response was the key to these differences between the N'Dama and Boran. The biopsies of the BM of the N'Dama cattle were hypercellular (scored 4.5±1.0 compared to 4.0 for controls) with mild hyperplasia of erythroid cells and mild hypoplasia of myeloid cells from 28 to 112 DPI, endowing the animals with higher haemopoietic potential that enabled them to replace most lost cells. In contrast, the Boran cattle had hypocellular (scored 2.4±1.1) BM biopsies with relative erythroid hyperplasia and myeloid hypoplasia, resulting in low capacity of cell replacement manifested as severe unremitting anaemia and leucopenia. The BM of both breeds showed moderate hyperplasia of cells of the mononuclear phagocyte system. Therefore, this study showed, for the first time, that BM response is a key determinant factor of trypanotolerance as it determines the animal's capability for blood cell regeneration.     

Polyamine content and drug sensitivities of different clonal lines ofLeishmania infantum promastigotes

Two isolates (skin and lymph node) ofLeishmania infantum obtained from a naturally infected dog were cloned and the free pools of polyamines for both complete isolates and clones were determined. Putrescine (Put) and spermidine (Spd) levels were highly variable among the lines studied, ranging from 0.89 to 2.1 nmol Spd/10⁷ promastigotes. The Put/Spd ratio was also variable (1.54–0.51) and correlated with the cell growth of the lines studied. There were important differences in the clones' sensitivites to difluoromethylornithine (DFMO) and Berenil, with some of the clones being almost refractory to the inhibitory effect of 50 M DFMO, whereas the growth of others was reduced by 60%; similar findings were obtained with 50 M Berenil.L. infantum sensitivites to DFMO and Berenil were correlated and apparently related to the values for the Put/Spd index.     

Immune depression and macroglobulinemia in experimental subchronic trypanosomiasis.

The effects of subchronic trypanosomiasis upon immune responses were examined in Trypanosoma gambiense infection and in subcurative treatment of T. brucei- and T- equiperdum-infected mice. About 60% of the mice infected with T. gambiense developed a subchronic infection similar to human trypanosomiasis, characterized by the absence of circulating trypanosomes. The animals died between 1 and 12 months after infection with elevated serum immunoglobulin M (IgM) levels (16 times the normal level). After 1 month of infection, the mice showed a normal primary antibody response against sheep erythrocytes, as tested by hemagglutination, despite their high serum IgM levels. After more than 1 month of infection, about 20% of the mice showed depressed hemagglutination titers (25% of control), whereas all relapsed mice that contained circulating parasites showed a pronounced suppression. Elimination of the blood parasites with Berenil treatment restored immune competence, which persisted until the relapse of the animals. Identical results were obtained in T. brucei-infected mice. Berenil treatment abolished the immune depression against sheep erythrocytes, but did not cure the animals, which relapsed with the development of a new state of immune depression. T. gambiense and T. brucei infections were always followed by a marked increase of serum IgM levels. Hypergammaglobulinemia was also induced in relapsing T. equiperdum-infected mice treated with Berenil. No immune depression against sheep erythrocytes could be detected. It appeared that immune depression was not the result of clonal exhaustion (measured by the serum IgM level) but seemed to be closely associated with the presence of living trypanosomes.     

The haematology ofTrypanosoma congolense infection in cattle I. Sequential cytomorphological changes in the blood and bone marrow of Boran cattle

Five adult Boran cattle (Bos indicus), infected with a clone ofTrypanosoma congolense IL13-E3 three years earlier and treated, were re-challenged with the same clone. Changes in the peripheral blood were monitored twice weekly, and events in the bone marrow (BM) were assessed by weekly biopsies of the sternal BM, until day 98 postinfection (dpi) when the three surviving animals were treated with diminazene aceturate. One animal died on 57 dpi whereas another was treated on 63 dpi when the packed cell volume was 15%. The infected animals developed anaemia, leucopenia and thrombocytopenia during the first peak of parasitaemia which persisted until the experiment was terminated. Three phases of BM response were demonstrated on light microscopic examination of BM smears. The first, the preparasitaemic phase represented by samples taken on 15 dpi, was an immunological response with slight but significant increases in lymphoblasts, lymphocytes, plasma cells and macrophages (Mø) whereas erythroid and granulocytic cells were unchanged. The second, the early parasitaemic or acute phase (21–57 dpi) associated with the development of anaemia, leucopenia and thrombocytopenia, was characterised by intensification of the immunological response, and an early but transient granulocytic hyperplasia. The third, the late parasitaemic or chronic phase (63–98 dpi) associated with persisting pancytopenia, was characterised by erythroid, megakaryocytic and Mø hyperplasia, dyserythropoiesis, granulocyte hypoplasia and return of lymphoid cell counts to preinfection numbers. Transmission electron microscopy confirmed these findings and showed that intact trypanosomes were not observed in the sinusoids and haemopoiesic compartment of the BM.This study demonstrates thatT. congolense infection the various blood cell lineages depending on the stage of infection. This suggests a fine control mechanism, presumably cytokine-mediated. Erythropoiesis, thrombopoiesis and monocytopoiesis were generally upregulated, whereas granulopoiesis was downregulated. However, haemopoiesis was generally ineffective as numbers of circulating blood cells remained below preinfection levels throughout the period of the study.     

The haematology ofTrypanosoma congolense infection in cattle I. Sequential cytomorphological changes in the blood and bone marrow of Boran cattle

Five adult Boran cattle (Bos indicus), infected with a clone ofTrypanosoma congolense IL13-E3 three years earlier and treated, were re-challenged with the same clone. Changes in the peripheral blood were monitored twice weekly, and events in the bone marrow (BM) were assessed by weekly biopsies of the sternal BM, until day 98 postinfection (dpi) when the three surviving animals were treated with diminazene aceturate. One animal died on 57 dpi whereas another was treated on 63 dpi when the packed cell volume was 15%. The infected animals developed anaemia, leucopenia and thrombocytopenia during the first peak of parasitaemia which persisted until the experiment was terminated. Three phases of BM response were demonstrated on light microscopic examination of BM smears. The first, the preparasitaemic phase represented by samples taken on 15 dpi, was an immunological response with slight but significant increases in lymphoblasts, lymphocytes, plasma cells and macrophages (Mø) whereas erythroid and granulocytic cells were unchanged. The second, the early parasitaemic or acute phase (21–57 dpi) associated with the development of anaemia, leucopenia and thrombocytopenia, was characterised by intensification of the immunological response, and an early but transient granulocytic hyperplasia. The third, the late parasitaemic or chronic phase (63–98 dpi) associated with persisting pancytopenia, was characterised by erythroid, megakaryocytic and Mø hyperplasia, dyserythropoiesis, granulocyte hypoplasia and return of lymphoid cell counts to preinfection numbers. Transmission electron microscopy confirmed these findings and showed that intact trypanosomes were not observed in the sinusoids and haemopoiesic compartment of the BM. This study demonstrates thatT. congolense infection the various blood cell lineages depending on the stage of infection. This suggests a fine control mechanism, presumably cytokine-mediated. Erythropoiesis, thrombopoiesis and monocytopoiesis were generally upregulated, whereas granulopoiesis was downregulated. However, haemopoiesis was generally ineffective as numbers of circulating blood cells remained below preinfection levels throughout the period of the study.     

T淋巴细胞清除促进脐血造血细胞的体外扩增

采用抗CD3或抗CD8单克隆抗体的补体细胞毒方法清除脐血单个核细胞 (MNC )中T淋巴细胞 ,CD34免疫亲和柱纯化MNC中CD34 +细胞 ,流式细胞技术 (FACS )分析细胞表面标志。将CD34 +细胞中加入含多种造血生长因子的培养基进行体外液态扩增 ,并观察粒 巨噬集落 (CFU GM )和多向祖细胞集落 (CFU GEMM )形成能力。结果CD3+或CD8+细胞清除组和MNC经CD34免疫亲和柱纯化后 ,CD34 +细胞分别为 5 9 5 2 %、 5 6 70 %和 5 0 72 % ,比未纯化组 (1 0 7% )纯度大幅度提高。抗CD3单抗清除 +CD34纯化组和单纯CD34纯化组经造血生长因子刺激培养第 14天 ,细胞总数分别扩增 110 40倍和 87 0 0倍。抗CD3单抗清除 +CD34纯化组、抗CD8单抗清除 +CD34纯化组和单纯CD34纯化组的CFU GM产率分别为 2 86 5 0± 12 0 2、2 88 5 0± 17 68和 2 19 5 0± 5 3 0 3,前者虽高于后者 ,但差异无显著性。CFU GEMM产率分别为 376 67± 43 2 4、 438 33± 36 73和 311 0 0± 40 11,抗CD3单抗清除 +CD34纯化组无显著差异 ,抗CD8单抗清除 +CD34纯化组显示出显著性作用 (P <0 0 5 )。     

Huntington''s disease and leucocyte adherence inhibition (LAI)

The in vitro proliferative response of bovine leucocytes from peripheral blood to LPS, PWM and Con A was monitored during the course of infection with T. congolense. The stimulatory effect of LPS and PWM on PBL was significantly decreased in infected cattle while the reduction of stimulatory response to Con A was less marked. There was a high background proliferation of unstimulated leucocytes from infected cattle. This increase in background counts correlated with the parasitaemia in that both features were abolished by treatment with the trypanocidal drug Berenil (4,4'-diamidino-diazoaminobenzene-diacetamide acetone). Co-cultivation of trypanosomes with PBL from normal cattle did not depress the responses of the latter to mitogens, and trypanosomes maintained in a cell-free medium failed to incorporate 14C-thymidine under the conditions used.     

Polymerase chain reaction and DNA probe hybridization to assess the efficacy of diminazene treatment in Trypanosoma brucei -infected cattle

Four of eight Ankole longhorn cattle experimentally infected with Trypanosoma brucei were treated with 7 mg/kg diminazene aceturate (Berenil, Hoechst AG, Germany) at day 71 postinfection. The trypanocidal activity was monitored using polymerase chain reaction (PCR) and DNA probe hybridization. When extracted parasite DNA (without host DNA) was used, as little as 1 fg per reaction, which is equivalent to about 1–10% of the DNA in a single trypanosome, produced a specific product that was visible as a 177-bp band in an agarose gel. In infected cattle, specific PCR products could be amplified at as early as 1 day postinfection. PCR signals remained positive during infection, except in one sample, although aparasitemic phases occurred. In cases where treatment resulted in a significant clinical improvement, PCR signals disappeared at 3–4 days after the administration of the drug. By contrast, in cattle that showed clinical signs of CNS involvement after treatment, although aparasitemic, and died before the termination of the experiment, specific products could be amplified on several occasions following treatment. The PCR signals generated after treatment could be further enhanced by subsequent slot-blot hybridization with a T. brucei-specific DNA probe. We conclude that PCR coupled with DNA probe hybridization provides a highly sensitive tool for the assessment of therapeutic efficiency and disease progression in trypanosome infections, especially in chronic infections when the level of parasitemia is low or when trypanosomes are sequestered at cryptic sites. Received: 29 May 1998 / Accepted: 18 August 1998     

Levels of complement in sera from inactive SLE patients, although decreased, do not influence in vitro uptake of apoptotic cells

BACKGROUND: Accumulation of apoptotic cells is considered relevant in the pathogenesis of systemic lupus erythematosus (SLE). Complement factors facilitate the clearance of apoptotic cells and, when decreased, might result in an increased amount of apoptotic cells found in SLE patients. OBJECTIVE: To determine the influence of complement profiles from inactive SLE patients on the in vitro phagocytosis of apoptotic cells. METHODS: Consecutive SLE patients (n=98) with inactive disease (SLEDAI < or =4) and 20 healthy controls (HC) were included. Levels of CH50, C3, C4, C1q, and C1r were measured. Human peripheral blood monocytes were isolated from healthy controls and cultured for 7 days to obtain monocyte-derived macrophages (MDM). Jurkat cells were irradiated with UVB to induce apoptosis. Phagocytosis was tested by incubation of MDM with apoptotic cells in the presence of serum and quantified as phagocytosis index (number of Jurkat cells internalized by 100 macrophages). Serum from 20 patients with CH50<65%, 20 patients with CH50 > or =65%, and 20 HC were used in this assay. RESULTS: All HC and 37% of patients had normal complement levels. CH50 level was decreased in 21% of patients, C3 in 52%, C4 in 29%, C1q in 2% and C1r in 44% of patients. Between patients and HC, differences in level of CH50, C3 and C4 were statistically significant. No difference in phagocytosis index between HC and patients, irrespective of their CH50 level, was detected. No correlation was found between the respective complement levels and phagocytosis index. CONCLUSION: In most SLE patients with inactive disease, levels of one or more complement components are decreased. However, decreased levels of complement do not result in a significantly reduced in vitro uptake of apoptotic Jurkat cells by MDM.     

The effect of antigen concentration and vaccine regimen on the immunity induced by membrane antigens from the midgut of Boophilus microplus.

Sheep and cattle were immunized with membrane antigens extracted from the midgut (GM) of the cattle tick Boophilus microplus, and antibody levels were measured by enzyme-linked immunosorbent assay (ELISA). One microgram of GM induced an antibody response in sheep comparable to that induced by 500 micrograms GM. Single or divided doses of 500 micrograms GM induced the same antibody levels in sheep over 12 weeks. Cattle vaccinated with either 500 micrograms GM in two doses or with 50 or 500 micrograms GM in three doses had significant antibody responses (P less than 0.05) and were equally protected (89%, 80% and 95%, respectively, calculated from tick egg weights) against challenge with 40,000 ticks, compared to control cattle. In another experiment, cattle vaccinated with 2.95 mg GM divided into 12 doses over 6 months had antibody levels that reached a plateau after 1.2 mg GM were administered, and were significantly protected (96%) against challenge.     

Level of complement activity and components C1, C4, C2, and C3 in complement response to bacterial challenge in malnourished rats.

In experimentally induced malnutrition in rats, there was no significant difference between the measured level of complement activity of the classical pathway (50% hemolytic complement [CH50]) and that of the alternative pathway (ACH50), although the levels of complement components C1, C4, C2, and C3 were depressed significantly. The complement activity showed a temporary elevation with a peak at 2 or 3 days after bacterial challenge with Staphylococcus aureus in rats, and we call this the complement response. After 3 days, CH50 and C3 in the malnourished rats and ACH50, CH50, and C3 in the well-nourished rats showed a significant increase, and C1, C4, and C2 in both groups tended to elevate. On the basis of these observations, the significance of the elevation of C3 in the complement response to bacterial infection showed a strong influence by enhancing the activation of both the classical and the alternative pathways, since C3 is known to be the junction of both complement pathways. In this way, C3 responded to an earlier stage than did the other components and may contribute to maintaining the body defense system against infection.     

Doramectin,a new avermectin highly efficacious against gastrointestinal nematodes and lungworms of cattle and pigs: two studies carried out under field conditions in Germany

Two field studies were carried out to confirm the efficacy of doramectin in cattle and pigs in Europe. A total of 40 cattle harbouring naturally acquired infections of gastrointestinal nematodes, includingOstertagia spp.,Oesophagostomum spp.,Cooperia spp.,Haemonchus spp.,Nematodirus spp. andTrichuris spp., were allocated to a treated or a control group (20 animals/group), and 100 harbouring naturally acquired infections of gastrointestinal nematodes and lungworms, includingOesophagostomum spp.,Metastrongylus spp.,Ascaris suum andTrichuris suis, were allocated to either a treated (60 pigs) or a control (40 pigs) group. Animals in the treated groups received an injection of doramectin at 200 g/kg (1 ml/50 kg) for cattle or 300 g/kg (1 ml/33 kg) for swine. Animals in the control groups received saline at 1 ml/50 kg for cattle or 1 ml/33 kg for swine. The cattle were injected by the subcutaneous route in the lateral mid-line of the neck and the pigs were injected intramuscularly in the neck. Faecal egg counts were determined for all animals on days –7, 0, 7, 14 and 21 of the studies, where day 0 was the day of treatment. The mean daily weight gain of doramectin-treated animals was significantly higher than that of the control animals over the 21 days of the studies (P<0.0007 for cattle andP=0.0001 for swine). At 21 days after treatment, the mean faecal egg counts of the doramectin-treated animals were significantly lower than those of the control animals and were reduced by 100% as compared with pretreatment levels. No adverse reaction to treatment was observed in any animal during either study. It is concluded that doramectin is highly efficacious in the treatment of mixed infections of gastrointestinal nematodes and lungworms in both cattle and pigs.