Spleen and lymph node cell populations, In vitro cell proliferation and interferon-y production during the primary immune response to Toxoplasma gondii

An animal model for the study of transient lymphadenopathy-splenomegaly during toxoplasmosis is presented. Injection of CBA/J mice with the low virulent, cyst-forming strain of Toxoplasma gondii (Pe strain) induces a three to four fold increase in weight and cellularity of spleen and lymph nodes with peak changes at 30-50 days after infection. The spleen displays marked haemopoiesis, a 30 fold increase in mononuclear phagocytes, and a two fold increase in Lyt2+ lymphocytes. Lymph nodes show a five fold increase in mononuclear phagocytes and a four and a half fold increase in Lyt2+ T cells. The increase in mononuclear phagocytes significantly alters T cell/macrophage ratios and this is associated with decreases in in vitro cell proliferation to mitogen and toxoplasma antigen. The relationship between alterations in cell balance of mononuclear phagocytes and T cell subsets and the expression of transient immune dysfunction can now be examined by modulating changes in these cell types.     

Immunohistochemical localization of toxoplasma antigen in reactive and neoplastic lymph nodes

Sixty-six formalin fixed, paraffin-embedded reactive and neoplastic lymph node biopsies were examined by the immunoperoxidase (PAP) procedure to localize toxoplasma antigen. 13:16 (81.25%) of the histologically suggestive toxoplasmic lymphadenitis and 4:8 (50%) of Hodgkin's lymphoma with histiocytic (epitheloid) cell infiltrates were positive. All other reactive and neoplastic biopsies were negative. Our data prove the usefulness of the PAP procedure as a specific and sensitive test to confirm the diagnosis of histologically suspicious toxoplasmosis. This study, however, is the first of its kind that demonstrates immunohistologically the association of toxoplasmosis with Hodgkin's lymphoma in the same lymph nodes. It also calls in question the nature of the histiocytes in lymphoid neoplasms and suggests the possibility that, at least in some lymphomas especially Hodgkin's, the histiocystic component may be due to the association of other conditions which are worth of further investigation.     

Angiostrongylus cantonensis: lymphoid cell responsiveness and antibody production in rats.

Angiostrongylus cantonensis-infected rats were examined for the presence of antigen sensitive lymphocytes, as assessed by the in vitro uptake of tritiated thymidine by cells of various lymphoid organs (cervical, mediastinal and mesenteric lymph nodes, spleen and periphereal blood), following stimulation by adult worm antigen. The lymphoid cell response of rats to A. cantonensis appeared to be local in nature in that significant responses were noted only in the cervical lymph node cells during the first 4 weeks of infection. The responses of spleen cells to phytohemagglutinin gradually declined as the infection progressed and this reduced responsiveness was statistically significant during the period of 5 to 10 weeks of infection. Homocytotropic antibody, demonstrated by 72-hour homologous passive cutaneous anaphylaxis, was detected throughout 2 to 17 weeks postinfection with a peak response at the 5th week of infection. The antibody was heat labile and sensitive to reduction by 2-mercaptoethanol and alkylation. Hemagglutinating antibody was first observed 5 weeks after infection and high titers occurred throughout 6 to 17 weeks postinfection.     

Failure to diagnose fatal disseminated toxoplasmosis in a bone marrow transplant recipient: the possible significance of declining antibody titres

A 46-year-old patient with acute myelogenous leukaemia developed lethal disseminated toxoplasmosis 8 weeks after allogeneic bone marrow transplantation. Clinical features included pulmonary infiltrates, respiratory insufficiency and neurological signs. Post-transplantation toxoplasma serological tests were characterised by declining IgG titres and failure to detect IgM, whereas titres of IgG against the various herpes viruses remained constant and even increased over the same period. Circulating toxoplasma antigen could not be detected. Post mortem, specific immune complexes were identified in serum. Autopsy revealed widely disseminated toxoplasmosis with several foci in the brain, lungs and various other organs as well as concomitant infection with cytomegalovirus.     

Sequential analysis of apoptosis induction in peripheral blood mononuclear cells and lymph nodes in the early phase of pathogenic and nonpathogenic SIVmac infection.

To investigate the role of apoptosis in the early phase of HIV infection, we used macaques infected with simian immunodeficiency virus strain mac (SIVmac) as a primate model and examined sequentially the characteristics of apoptosis of lymphocytes in peripheral blood mononuclear cells (PBMCs) and lymph nodes in the early phase of SIVmac infection. Five macaques infected with a pathogenic strain of SIV, SIVmac239, were analyzed during the first 4 weeks after infection. Peripheral CD4+ and CD8+ cells transiently decreased at 1 week postinfection. The percentage of apoptotic cells in cultured PBMCs increased from about 2 weeks postinfection. The number of apoptotic cells in lymph node sections was higher on days 13 and 28 postinfection than before infection and on day 5 postinfection. Fas antigen expression on peripheral lymphocytes was upregulated from day 8 postinfection. These results indicate that apoptosis is induced about 2 weeks after SIVmac239 infection, following the upregulation of Fas antigen expression on lymphocytes. Since apoptosis was induced about 1 week after the decrease in peripheral CD4+ and CD8+ cell counts, it appears that the apoptosis induction does not play an important role in the transient lymphopenia in the early phase of SIVmac infection. In macaques infected with a nonpathogenic derivative of SIVmac239, SIVmac delta nef, apoptosis of lymphocytes was induced as it was in SIVmac239-infected macaques, but to a lesser degree, suggesting a correlation between the extent of apoptosis induction in lymphocytes in the early phase of SIVmac infection and the pathogenicity of SIVmac.     

Role of lymphocytes in collagen induced arthritis.

We investigated the time related changes of lymphocyte subsets in the blood, regional lymph node and thymus during the development of collagen induced arthritis in mice. Flow cytometric analysis showed that Lyt2+ T, but not L3T4+ T cells in the blood or regional lymph node, was significantly reduced throughout the observation. The number of Lyt2+ T cells was decreased in lymph nodes of collagen immunized vs adjuvant controls while B cells were increased and L3T4+ T cells were not different. These might act as a potential factor for the onset of collagen induced arthritis. The reduction of Lyt2+ cells was not influenced by thymic T cell maturation; it is conceivable that the main immune organ is the regional lymph node.     

不同途径感染弓形虫小鼠在脑内形成包囊的研究

目的用3种不同途径感染Fukaya株弓形虫速殖子,观察弓形虫感染小鼠慢性期病变特点及虫体在脑内的成囊过程,以期寻求一个稳定、易建的慢性感染动物模型,为弓形虫病的病理诊断提供依据,并对弓形虫的致病机理加深理解。方法弓形虫Fukaya株速殖子(5×104个)分别以腹腔、皮下和口服途径感染小鼠,给适量药物使之形成慢性感染,并与不给药组做对照,于感染后第3d、6d1、4d2、1d、28d、42d和90d,取脑进行间接免疫酶染色,统计脑内虫体数量及形成包囊情况。结果不给药组第3d、6d与给药组第6d,3种感染途径的腹腔含虫数比较:均为腹腔感染>皮下感染>经口感染。比较小鼠脑内虫体分布:腹腔感染组,第28d的脑内虫体达到高峰,此时脑内包囊最多。皮下感染组,第21d的脑内虫体最多,脑内包囊也多。经口感染组,第21d脑内虫体最多,但脑内偶见包囊。经口感染Fukaya株速殖子似不易成囊。经腹腔、皮下和口服感染虫体的小鼠存活率在第42d分别为100%、66%、80%。结论弓形虫感染慢性期小鼠脑多被累及。腹腔与皮下感染弓形虫Fukaya株速殖子比口服易成囊,经腹腔感染方式建立弓形虫慢性感染动物模型较稳定。     

The immune response of regional lymph nodes during the early stages of Fasciola hepatica infection in cattle

In this study we examined regional immune responses to Fasciola hepatica infection in the natural ruminant host. Naïve cattle and those pre‐exposed to a drug‐abbreviated infection were subsequently challenged and lymph nodes extracted at slaughter. In vitro proliferation and cytokine production by mononuclear cells isolated from hepatic and mesenteric lymph nodes were measured after culture with whole fluke antigen (WFA). Hepatic lymph node cells had a significantly greater response to parasite antigen than mesenteric lymph node cells (P < 0·02), although there was no difference in the magnitude of the proliferative response between naïve and pre‐exposed challenged cattle. Mononuclear cells from hepatic lymph nodes produced interferon gamma, interleukin 2 and interleukin 4 after culture with parasite antigen, indicative of a mixed, T helper type 0, response. Comparison of the hepatic node response to a variety of F. hepatica antigens showed that proliferation was lower after culture with cathepsin‐L, than with a high molecular weight fraction, WFA or excretory–secretory antigen. Cell culture supernatant fluid from unstimulated hepatic lymph node cells showed an IgG1 response to antigens of 48, 52–70, 82, 96 and 120–190 kDa on Western blot in pre‐exposed, but not naïve, challenged animals.     

Cerebral toxoplasmosis in a patient with Hodgkin's disease

A case is described of a patient presenting with enlarged lymph nodes and in whom a diagnosis of acute toxoplasmosis was made. The patient later developed Hodgkin's disease for which chemotherapy was started. Reactivation of the quiescent toxoplasma infection took place with devastating results. Prophylactic treatment in such cases is discussed.     

Discrimination between patients with acquired toxoplasmosis and congenital toxoplasmosis on the basis of the immune response to parasite antigens

Many persons infected with Toxoplasma gondii develop ocular lesions. Immunologic parameters in the response to T. gondii were evaluated in infected persons with and without ocular lesions and in noninfected controls. Subjects were divided into groups on the basis of presence of serum antibodies to T. gondii, presence of ocular lesions, and clinical history. Production of interleukin-2 and interferon-gamma by peripheral blood mononuclear cells from patients with probable congenital toxoplasmosis was decreased, compared with that in persons with presumed acquired infection. Cell proliferation and delayed-type skin reaction induced by soluble toxoplasma tachyzoite antigen followed the same pattern. Asymptomatic persons showed high levels of interleukin-12 and interferon-gamma, whereas persons with ocular lesions had high interleukin-1 and tumor necrosis factor-alpha responses toward soluble toxoplasma tachyzoite antigen. These data suggest that patients with ocular disease due to congenital infection show tolerance toward the parasite. Furthermore, susceptibility to ocular lesions after acquired toxoplasmosis is associated with high levels of interleukin-1 and tumor necrosis factor-alpha, whereas resistance is associated with high levels of interleukin-12 and interferon-gamma.     

绵羊弓形虫TgSheepHn1对小鼠的病理损伤及其抗原分布特点

目的 为了探究绵羊弓形虫分离株ToxoDB#9(TgSheepHn1)感染Swiss小鼠后,弓形虫在各脏器的分布及病理组织学损伤特点。方法 选取10⁴浓度的弓形虫速殖子腹腔接种小鼠,采用H&E及IHC方法分析小鼠各脏器中弓形虫抗原的分布以及病理损伤特点。结果 昆明小鼠在急性感染期病理损伤主要表现在肺脏、肝脏、脾脏、肠系膜淋巴结及小肠,其他脏器损伤较轻或无明显损伤;弓形虫抗原在脾脏,肠系膜淋巴结,肾上腺,肝脏胆囊管肌层,生殖器官分布较多,大脑,心肌,肺脏,肾脏,膀胱及小肠也可观察到弓形虫抗原的分布。结论 TgSheepHn1对昆明小鼠的免疫及消化系统损伤较重,抗原分布广泛,免疫及生殖系统是该虫株的主要靶器官。     

Chronic lymphadenopathic toxoplasmosis. A case with marked hyperglobulinemia and impaired delayed hypersensitivity responses during active infection.

A patient with lymphadenopathic toxoplasmosis characterized by prolonged symptoms and repeated relapses with isolation of toxoplasma from lymph nodes is described. As the disease persisted and progressed, striking immunologic changes occurred that ultimately resulted in a state of extreme hyperglobulinemia associated with impaired delayed hypersensitivity responses. The case in question illustrates that progressive infection may occur in the face of high antibody levels of all immunoglobulin types whereas the only demonstrable immunologic impairment was of delayed hypersensitivity.     

Mic1-3 knockout of Toxoplasma gondii is a successful vaccine against chronic and congenital toxoplasmosis in mice

BACKGROUND: We evaluated a new vaccine, Mic1-3KO, against both chronic and congenital toxoplasmosis in mice. Mic1-3KO is a mutant strain of Toxoplasma gondii RH that lacks the mic1 and mic3 genes. METHODS: OF1 mice were vaccinated with Mic1-3KO tachyzoites and challenged orally with T. gondii (strain 76K). Immune responses and protection against chronic infection (cyst load in brain tissue) and congenital infection (maternofetal transmission, survival, body weight, and chronic infection in pups) were evaluated. RESULTS: Mic1-3KO induced a strong humoral and cellular T helper (Th) 1 response and conferred highly significant protection against chronic infection (>96% reduction in cysts in brain tissue). Fewer infected fetuses were observed in vaccinated dams that were infected during pregnancy than in nonvaccinated infected dams (4.6% vs. 33.3%). All pups born to vaccinated infected dams survived and had the same weight as those born to nonvaccinated uninfected dams. Furthermore, they had significantly fewer cysts in brain tissue (>91%) than pups from nonvaccinated infected dams. During pregnancy, protection against congenital disease was associated with a cellular Th1 response regulated by interleukin-10. One month after delivery, vaccinated infected dams had >96% fewer cysts in their brain tissue than nonvaccinated infected dams. CONCLUSION: Mic1-3KO is an effective vaccine against chronic and congenital toxoplasmosis.     

Cytomegalovirus infections and toxoplasmosis in heart transplant recipients in Sweden.

The morbidity of cytomegalovirus (CMV) infection and toxoplasmosis was evaluated in 75 heart transplant recipients. Among the 73 patients who survived more than one week after transplantation, 16 (22%) acquired primary CMV infection and 30 (41%) had evidence of secondary infection. All CMV seronegative recipients receiving hearts from seropositive donors developed CMV infection. The majority of infections (42/46) occurred during the first 4 months after transplantation. Overall, the incidence of symptomatic CMV disease was 44%. The infections were generally mild and only 1 death was attributed to primary CMV disease complicated by bacterial septicaemia and multiple organ failure. The severity of CMV disease was greatest among those with primary infection. There were 3 cases of toxoplasmosis. Two patients were toxoplasma seronegative before transplantation and developed clinical and serological signs of infection 2-3 months after transplantation despite receiving organs from seronegative donors. Of toxoplasma seronegative recipients receiving allografts from seropositive donors 3/4 were prophylactically treated with pyrimethamine for 6 weeks. None developed clinical or serological signs of toxoplasmosis while one patient who received trimethoprim-sulfamethoxazole had a subclinical infection.     

Interference with major histocompatibility complex class II-restricted antigen presentation in the brain by herpes simplex virus type 1: a possible mechanism of evasion of the immune response.

Host survival of herpes simplex virus type 1 (HSV-1) infection depends on the establishment of latent infections in both peripheral and central nervous systems. Strains of HSV-1 that are successful in escaping the immune response produce a lethal infection. We now report a possible mechanism of immune response evasion used by HSV-1. After intraocular inoculation of mice, HSV-1 strain F established a latent infection in the brain, whereas strain KOS did not. The immune response to HSV-1 infection (strains KOS and F) in the brain was characterized by induction of major histocompatibility complex class II expression and recruitment of CD4+ and CD8+ cells to highly restricted sites of intracerebral viral infection. Major histocompatibility complex class II antigen expression was primarily intracellular in strain KOS infection centers and at the cell surface in strain F infection centers. We propose that major histocompatibility complex class II-restricted viral-antigen presentation to T cells is interrupted during strain KOS infections, thereby allowing KOS infection to evade T-cell-mediated events that would normally protect the host from a lethal infection. Immunocompromised mice (athymic or irradiate mice) could not survive strain F infections; however, latent F infections were established in irradiated mice reconstituted with naive lymph node and spleen cells. These data suggest that class II-restricted presentation of viral antigens is required for the control of HSV-1 infections in the nervous system.     

弓形虫Chinese 1基因型Wh6弱毒株感染小鼠抗强毒株致死性感染的免疫保护作用

目的 研究我国流行的优势基因型Chinese 1弱毒Wh6株感染抗致死性强毒Wh3株攻击感染的保护力,探讨其潜在的制备减毒活疫苗的价值。方法 将30只BALB/c雌性小鼠随机分为3组(I,II,III组),每组10只。取弱毒株弓形虫保种小鼠脑组织,分离包囊,计数。I组小鼠灌胃包囊25-35个;II组给与PBS对照;III组正常小鼠不予任何干预。35 d后,I组感染小鼠脑组织压片镜检,查见典型弓形虫包囊,表明慢性弓形虫感染BALB/c小鼠模型建立成功。分别取Wh3株速殖子(3 000个),腹腔感染I组和II组小鼠,观察小鼠存活及腹腔虫荷;同时剖杀小鼠,收集脾细胞培养上清,采用流式细胞术、荧光定量PCR、酶联免疫吸附试验等检测脾细胞中的Th1、Th2细胞因子水平。结果 II组对照鼠在感染Wh3株弓形虫速殖子后第7 d内死亡5只,第8 d剩余5只全部死亡,随机取3只死亡小鼠对其腹腔进行计数,计数结果为(1.28±0.035 1)×10⁶/mL;而I组小鼠截止实验结束全部存活(P<0.01)。II组鼠脾细胞培养上清Th1细胞因子IFN-γ、IL-12和Th2细胞因子IL-10水平相比I组显著升高(P<0.001)。其中Th1细胞因子升高程度明显高于Th2细胞因子,巨噬细胞向Th1方向极化。结论 用弱毒株Wh6包囊攻击感染BALB/c鼠,可诱导强力的抵抗Wh3强毒株致死性感染的免疫保护力。Chinese 1基因型Wh6株具有候选减毒活虫疫苗研究的潜在价值。     

Suppressor T cells for delayed-type hypersensitivity in susceptible mice infected with Mycobacterium lepraemurium

Spleen cells from immunodepressed C3H mice, i.e., mice inoculated intravenously 4 months earlier with 1 X 10(7) Mycobacterium lepraemurium (Mlm) bacilli, were separated into different populations, and the T-cell-enriched population was treated further with gamma-irradiation or specific anti-Lyt antibodies plus complement. The cell populations obtained were then adoptively transferred to normal and Mlm-sensitized syngeneic mice in order to investigate whether or not suppressor cells regulate the delayed-type hypersensitivity (DTH) reaction to specific antigens. A radiosensitive cell population expressing the Lyt 1+, 2+ phenotype had the capacity to depress the induction (afferent phase) of DTH reaction. In contrast, a radioresistant cell population expressing the Lyt 1+, 2- phenotype possessed the capacity to depress the expression (efferent phase) of the cutaneous reaction. Thus, distinct populations of suppressor cells, each regulating a different phase of DTH, are induced in the spleen of Mlm-infected mice.     

High expression of osteoglycin decreases gelatinase activity of murine hepatocarcinoma Hca-F cells

AIM: To investigate the possible correlation between osteoglycin expression and gelatinase activity of mouse hepatocarcinoma Hca-F cells. METHODS: A eukaryotic expression plasmid pIRESpuro3 osteoglycin(+) was constructed and transfected into Hca-F cells to investigate the possible correlation between osteoglycin expression and gelatinase activity of Hca-F cells cultured with extract of lymph node, liver, spleen or in DMEM medium. The activity of gelatinases was examined through zymographic analysis. RESULTS: High expression of osteoglycin attenuated the gelatinase activity of Hca-F cells cultured with extract of lymph node, and at the same time, decreased the metastatic potential of Hca-F cells to peripheral lymph nodes in vivo . CONCLUSION: High expression of osteoglycin decreases the gelatinase activity of Hca-F cells cultured with extract of lymph node; regulation of gelatinase activity might be one of mechanisms that osteoglycin contributes to lymphatic metastasis suppression.     

Oral administration of cyclosporin does not prevent expansion of antigen-specific,gut-associated,and spleen lymphocyte populations duringChlamydia trachomatis proctitis in nonhuman primates

To study the effects of oral cyclosporin (CsA) administration on immune responses in the gastrointestinal tract, humoral and cellular immune responses were studied in CsA-treated nonhuman primates having Chlamydia trachomatis proctitis (lymphogranuloma venereum, LGV). There was no apparent effect of CsA treatment on the gross or microscopic appearance of LGV proctitis, but CsA-treated animals, with or without LGV infection, had lymphoid hyperplasia of spleen and mesenteric lymph nodes. CsA treatment inhibited the primary antibody response to LGV, inhibited peripheral blood lymphocyte mitogen-induced proliferation and IL-2 production, and inhibited LGV-specific proliferation of peripheral blood lymphocytes. In contrast, mitogen-stimulated proliferation of spleen, mesenteric lymph node, and lamina propria lymphocytes was not significantly inhibited in CsA-treated animals. In addition, LGV-specific proliferation of spleen and mesenteric lymph node lymphocytes was not inhibited. High mitogen-stimulated IL-2 production of lamina propria lymphocytes was only partially inhibited in CsA-treated animals. In vitroCsA treatment had the expected inhibitory effects on mitogen- and antigen-induced proliferation of spleen and mesenteric lymph node lymphocytes. Thus, although oral cyclosporin inhibits the antibody and proliferative responses of peripheral blood lymphocytes to antigens and mitogens in animals having Chlamydia trachomatis proctitis, it does not prevent the expansion of antigen-specific, gut-associated, and spleen lymphocyte populations.Part of this work has been published as a preliminary report in abstract form (Clinical Research 34:446A, 1986).