ELISA for platelet-associated IgG, IgM, and C3, and their clinical application

The platelet-associated IgG (PAIgG) has been reported to elevate in the patients with idiopathic thrombocytopenic purpura (ITP) and other autoimmune diseases. However, low PAIgG levels have been often recognized in thrombocytopenia. We speculated about the increasing of other platelet-associated proteins in those patients, and tried to determine platelet-associated IgM (PAIgM) and platelet-associated C3 (PAC3) using a high sensitive competitive micro-ELISA as well as PAIgG. Our results showed the specific elevation of PAIgM and PAC3 in thrombocytopenia as well as the PAIgG level (p less than 0.01). Further, the weak correlations among these levels were found (PAIgG/PAIgM: n = 7, correlation coefficient (r) = 0.55, PAIgG/PAC3: n = 73, r = 0.61, PAIgM/PAC3: n = 56, r = 0.39). We discussed on the possibility that the PAIgM and PAC3 also could be an indicator for the platelet injury and may cause the short platelet life span resulting thrombocytopenia as well as PAIgG.     

Enhancement of interleukin-2 and γ-interferon productionin vitro on cord blood lymphocytes andin vivo on primary cellular immunodeficiency patients with thymic extract (Thymostimulin)

Cord blood mononuclear cells (MNC) were isolated from 20 normal full-term newborns. These MNC were preincubated with either 50, 100, or 200 µg/ml Thymostimulin or without Thymostimulin. The interleukin-2 (IL-2) and -interferon (-IFN) production, cytotoxicity, and lymphoproliferation and IL-2 receptor (Tac) expression were all significantly increased after Thymostimulin treatment. For evaluation of thein vivo effect, two combined-imimunodeficiency patients defective on the thymic level, one with progressive BCG infection, and one with DiGeorge syndrome were used. Before Thymostimulin treatment, the patient's MNC did not produce sufficient amounts of IL-2 and -IFN. The cytotoxicity and lymphoproliferation were also low. After Thymostimulin treatment, the IL-2 and -IFN production, cytotoxicity, and lymphoproliferative response were enhanced. These results suggest that Thymostimulin may be beneficial in the clinical treatment of primary cellular immunodeficiency. The improved immune reactivity including cytotoxicity and enhanced IL-2 and -IFN production in the Thymostimulin treatment also indicates that there may be a beneficial effect on the combination of chemotherapy and Thymostimulin.     

Surface markers of cloned human T cells with helper or suppressor activity on pokeweed mitogen-driven B cell differentiation

Human spleen T cells stimulated with pokeweed mitogen (PWM) were cloned under limiting conditions in microculture systems using interleukin 2 and irradiated autologous cells. Clones were screened for helper or suppressor activity on PWM-dependent B cell differentiation by adding cell aliquots to either isolated B cells and PWM or to mixtures of T and B cells and PWM. Out of 97 clones tested, 14 promoted intense B cell differentiation, as assessed by measurements of secreted IgG, and 6 strongly inhibited B cell maturation induced by spleen T cells. All the selected clones maintained their original activity after short-term clonal expansion; in addition, a similar (helper or suppressor) effect was detected when the total number of plasma cells per well was evaluated. Suppressor clones had no cytolytic activity on autologous T and B cell blasts, K562 cells or antibody-coated L 1210 mouse cells. Nine helper and 6 suppressor clones were analyzed for a battery of surface markers. All the clones were E rosette-positive and expressed HLA-DR (Ia) antigens. Fcmu receptor was present on a single helper clone, whereas Fc gamma receptor was expressed on a suppressor clone only. All but two clones expressed the OKT4+/ OKT8-, a single suppressor clone was OKT8+/OKT4-, whereas coexpression of OKT4 and OKT8 antigens was detected in one helper clone. Thus, the claim that helper T cells are OKT4+/OKT8- and suppressor T cells are OKT4-/OKT8+ is not supported by the analysis of their phenotype at the clonal level.     

A quantitative ELISA procedure for the measurement of membrane-bound platelet-associated IgG (PAIgG)

A quantitative ELISA assay for the measurement of in vivo bound platelet-associated IgG (PAIgG) using intact patient platelets is presented. The assay requires quantitation and standardization of the number of platelets bound to microtiter plate wells and an absorbance curve using quantitated IgG standards. Platelet-bound IgG was measured using an F(ab')2 peroxidase labeled anti-human IgG and o-phenylenediamine dihydrochloride (OPD) as the substrate. Using this assay, PAIgG for normal individuals was 2.8 +/- 1.6 fg/platelet (mean +/- 1 SD; n = 30). Increased levels were found in 28 of 30 patients with clinical autoimmune thrombocytopenia (ATP) with a range of 7.0-80 fg/platelet. Normal PAIgG levels were found in 26 of 30 patients with nonimmune thrombocytopenia. In the sample population studied, the PAIgG assay showed a sensitivity of 93%, specificity of 90%, a positive predictive value of 0.90, and a negative predictive value of 0.93. The procedure is highly reproducible (CV = 6.8%) and useful in evaluating patients with suspected immune mediated thrombocytopenia.     

Association of increased platelet-associated immunoglobulins with thrombocytopenia and the severity of disease in secondary dengue virus infections

Severe thrombocytopenia and increased vascular permeability are two major characteristics of dengue haemorrhagic fever (DHF). To develop a better understanding of the roles of platelet-associated IgG (PAIgG) and IgM (PAIgM) in inducing thrombocytopenia and its severity of disease in patients with secondary dengue virus infection, the relationship between the PAIgG or PAIgM levels and disease severity as well as thrombocytopenia was examined in 78 patients with acute phase secondary infection in a prospective hospital-based study. The decrease in platelet count during the acute phase recovered significantly during the convalescent phase. In contrast, the increased levels of PAIgG or PAIgM that occurred during the acute phase of these patients decreased significantly during the convalescent phase. An inverse correlation between platelet count and PAIgG or PAIgM levels was found in these patients. Anti-dengue virus IgG and IgM activity was found in platelet eluates from 10 patients in an acute phase of secondary infection. Increased levels of PAIgG or PAIgM were significantly higher in DHF than those in dengue fever (DF). An increased level of PAIgM was associated independently with the development of DHF, representing a possible predictor of DHF with a high specificity. Our present data suggest that platelet-associated immunoglobulins involving antidengue virus activity play a pivotal role in the induction of thrombocytopenia and the severity of the disease in secondary dengue virus infections.     

The role of interleukin-4 in IgE and IgG subclass formation

Conclusions Over the last 5 years, three major new findings were made regarding the mechanism of regulation of IgE and IgG subclass antibody formation. First, it was shown that IL-4 induces B cells to secrete IgE, murine IgG1 and human IgG4 and that IFN- and IL-2 inhibit this effect. Second, it was found that cloned murine T helper cells can be divided into two types: T_h1, secreting IL-2 and IFN-; and T_h2, secreting IL-4 and IL-5. Third, murine mast cells, like T_h2, secrete IL-4 and IL-5 but not IL-2 and IFN-. Soon after these in vitro data were obtained, direct and indirect evidence was obtained demonstrating that IL-4 and IFN- also act antagonistically on IgE formation in vivo. Collectively, this new information is a major breakthrough and demonstrates the important role of lymphokines in determining the Ig isotype secreted by B cells, particularly IgE and certain IgG subclasses. However, many aspects of IgE and IgG subclass regulation are not yet resolved and in particular, it is not clear what is abnormal in the lymphokine-regulated IgE antibody formation in atopic patients.The questions regarding isotype regulation which are presently studied extensively in many laboratories are the following: what is the precise molecular mechanism of the switch from IgM to IgE or IgG subclass. In particular, what is the effect of IL-4 in the induction of the switch mechanism? Also, is IL-4 only affecting the IgM to IgE switch or is it also important in the differentiation of IgE-secreting cells as some in vitro experiments suggest? In the mouse, many experiments indicate that IgGl can be formed in vivo independently of IL-4 and this may also be the case for IgG4 in man. The strict linkage of IL-4-induced IgE and IgG1 in vitro does not always seem to occur in vivo.A very important question: how do allergens or helminthic parasites selectively induce the apparent T helper cell and IL-4-dependent IgE and IgG4 antibody formation in man? It is unlikely that two lineages of T helper cells exist and that allergens and helminthic parasites interact only with the IL-4 producing T_h2 cells. Instead, it appears that allergens and parasites affect the T_h0 to T_h2 differentiation through interaction with accessory cells or perhaps by a direct effect on B cells. The latter is suggested by the fact that not all polyclonal B cell activators prepare B cells to respond to IL-4 with IgE secretion. In the mouse, LPS is a far better B cell activator than PRP for IL-4-induced IgE secretion, whereas PRP is equal to LPS in IL-4-induced IgG1 formation. Another mechanism by which allergens and helminthic parasites could induce IgE formation is via mast cell activation. If these antigens nonspecifically activate mast cells to secrete IL-4, this IL-4 could induce the IgM to IgE switch and may also induce the T_h0 to T_h2 differentiation. Allergens presumably immunize the host via penetration of the skin and respiratory and gastrointestinal tract, anatomic sites which are rich in mast cells. Helminthic infections induce a large mastocytosis in the intestinal tract and GVHD which also induces polyclonal IgE formation, causes degranulation of the skin mast cells. These observations support the notion that mast cells may play a role in the IgE formation. Although highly speculative at this time, it is possible and worthwhile to test this interesting hypothesis.Another unresolved question is: what is abnormal in the regulation of IgE antibody production in atopic patients? Do the patient's T helper cell produce too much IL-4 or not enough IFN-? Does IL-4 preferentially induce the IgM to IgE rather than IgM to IgG4 switch? These questions are being addressed experimentally at this time, however, no clear cut answers have been obtained.Despite the many unresolved questions regarding the IL-4-dependent IgE-regulatory mechanism, the availability of purified lymphokines together with advanced methods in molecular and cell biology currently available will result in rapid progress of the understanding of the IgE and IgG subclass regulation both in normals and atopic patients. Furthermore, the new information is likely to lead to new therapeutic interventions that may normalize the IgE antibody formation in atopic patients. It should be possible to manufacture drugs, soluble IL-4 receptors or neutralizing monoclonal antibodies to IL-4 that down-regulate IL-4 effects and inhibit excess IgE antibody formation. Alternatively, enhancers of IFN- or IL-2 formation may become useful as new therapeutic agents for allergic disorders. Finally, mast cell stabilizers that prevent mast cells from forming IL-4 or that interfere with the postulated role of mast cells in the IgE antibody up-regulation may be developed. Although it is not possible to predict where these findings will lead us, future research on the role of cytokines in allergy is likely to bear fruit in the next decade.     

Correlation between increased platelet-associated IgG and thrombocytopenia in secondary dengue virus infections

Although the public health impact of dengue is increasing rapidly, the mechanism of thrombocytopenia in this disease remains unknown. To elucidate this mechanism, the relationship between platelet-associated IgG (PAIgG) and platelet count in 53 patients in the acute phase of secondary dengue virus infection was investigated in a prospective-hospital-based study. A significant inverse correlation between the two parameters was found in these patients, while no correlation was observed in healthy volunteers. The low baseline platelet counts during the acute phase in 12 patients with secondary dengue virus infection significantly increased during the convalescent phase, while the increased PAIgG levels during the acute phase in these patients significantly decreased during the convalescent phase. Anti-platelet IgG autoantibody was detected rarely in the plasma of 53 patients with secondary dengue infection. The involvement of anti-dengue virus IgG was also shown in platelets from all of 8 patients in the acute phase of secondary dengue virus infection. These findings suggest that PAIgG formation involving anti-dengue virus IgG plays a pivotal role in the induction of transient thrombocytopenia during the acute phase of secondary dengue virus infection.     

Enhanced Interferon-γ by CD8+ CD28− Lymphocytes from HIV+ Patients

Flow cytometric analysis of T cells from HIV⁺ and normal individuals activated for 15 hr showed that the percentage of cells producing interferon- (INF) was enhanced approximately threefold (39 compared to 14%) in the HIV⁺ CD8⁺ population. Activation modes, other than anti-CD3 with PMA, were ineffective, and in no case did the percentage of HIV⁺ CD4⁺ T cells show increased INF production over controls. Enhanced INF production was not induced by either anti-CD3 or PMA alone, or anti-CD3 or ConA with anti-CD28, or enhanced by N-acetylcysteine. In contrast to INF production, the percentage of CD4⁺ T cells producing interleukin-2 (Il-2) greatly exceeded that of the CD8⁺ T cells. The results from flow cytometry analyses of HIV⁺ CD8⁺ T cells was supported by quantitative analysis of INF mRNA (by PCR) and INF secretion by ELISA. These methods showed a sixfold and three- to fivefold increase, respectively, on a per cell basis. As HIV infection progresses, as shown by loss of CD4⁺ T cells, the proportion of CD8⁺ CD28^– T cells increases, and it is this T cell subset that is responsible for 80% or more of the enhanced INF production. The enhanced INF in HIV⁺ patients derives from two factors: the increase in CD8⁺ CD28^– cells to 70% and the percentage producing INF (60%, compared to 21% for CD8⁺ CD28⁺ cells). Our findings of a substantial increase in INF production in HIV infection arising from the increased number of CD8⁺ CD28^– T cells are compatible with clinical studies which show elevated INF in HIV⁺ serum and INF producing CD8⁺ T cells dominating HIV⁺ lymph nodes. We also found a significantly decreased proliferative response of the HIV⁺-derived CD8⁺ T cell fraction with coactivator anti-CD-28, in contrast to PMA (with anti-CD3), which is probably a reflection of the diminished population of CD8⁺ CD28⁺ T cells in HIV⁺ donors compared to normal donors (30.7 compared to 67.9%).     

Frequencies of CD4+ T cells reactive with Plasmodium chabaudi chabaudi: distinct response kinetics for cells with Th1 and Th2 characteristics during infection

The functional heterogeneity of the CD4⁺ T cell response toPlasmodium chabaudi has been evaluated. Using a limiting dilutionassay system and a variety of assays to detect -interferon (IFN-),interleukln-2 (IL-2), IL-3, and T helper (T_h) cells for malaria-specificantibody production, the precursor frequencies of P. chabaudl-reactiveT cells have been calculated. The patterns of lymphokines producedby individual microcultures of the limiting dilution assay generallysupported the Idea of two functionally distinct CD4⁺ subsets:one which produces IFN- and IL-2 (T_h1) and one which Is an effectivehelper cell for antibody production (T_h2) However, it couldnot be determined whether the overiapping functions observedin some cultures represented T cells which could produce allfactors or separate clones which were developing In the samewells. During the first 14 days of an erythrocytic Infectionof P. chabaudi the predominant T cell response was of the T_h1-tupe.The frequency of these cells decreased after 14 days. By 3 weeksafter Infection the CD4⁺ T cell response was characterized byT_h2 cells, as defined by their ability to act as helper cellsin the production of malaria-specific antibody. These data supportthe hypothesis that early clearance of P. chabaudi may be antibody-Independentbut that the final clearance mechanism coincides with the appearanceof helper cells and antibody.     

Effect of carbimazole treatment on specific and non-specific immunological parameters in patients with Graves' disease.

Twenty-two patients with newly diagnosed Graves' disease (GD) were treated with carbimazole (CBZ) for 6 months. Thyroid stimulating immunoglobulins (TSI) and T cell subsets were studied prior to treatment and after 3 and 6 months of therapy. TSI were measured on human thyroid epithelial cell monolayers by the cAMP production after the addition of highly purified GD IgG. Before treatment, serum IgG from 20 out of the 22 patients (91%) stimulated cAMP production significantly compared to normal IgG. The mean index of cAMP production (GD IgG relative to normal IgG) was 2.15. After 3 months of CBZ treatment, a non-significant decrease of the mean cAMP production index was observed, whereas it was significantly decreased at the end of the 6 month course of therapy. Before treatment, total T cells (OKT3+), helper/inducer T cells (OKT4+) and suppressor/cytotoxic T cells (OKT8+) were all significantly decreased compared with controls. After 3 or 6 months of CBZ therapy, both total T cells and helper/inducer T cells returned to a normal level, while cytotoxic/suppressor T cells remained at the same low level. Taken together, these data indicate that treatment with CBZ leads to an early increase of helper/inducer T cells followed 3 months later by a decrease of the TSI level with no change in decreased suppressor/cytotoxic T cells. The disappearance of TSI following the increased helper/inducer T cell level suggests that an anti-idiotypic reaction may have occurred, and the persistent decrease of the suppressor/cytotoxic T subset that CBZ therapy does not act upon the underlying autoimmune disease.     

Expression of surface membrane IgG on pokeweed mitogen-reactive anti-tetanus toxoid antibody-producing cells

Anti-tetanus toxoid antibody-producing cells, differentially expressing surface membrane IgM, were analyzed for the additional expression of surface membrane IgG. ⁺ and ^– cells were rosetted with anti--ox red blood cells and separated by density centrifugation into fractions enriched or depleted or ⁺ cells. These B-cell subsets were assayed for the production of IgM and IgG anti-tetanus toxoid antibody and total IgM and IgG. The results indicated that the majority of anti-tetanus toxoid antibody synthesis in the ^– fraction was by ⁺ cells. In the ⁺ fraction, however, both IgM and IgG anti-tetanus toxoid antibody production was detected in the ^+– and ⁺⁺ fraction. The inclusion of isotype-specific antisera during the first 2 days of culture further established that was expressed on the surface of the majority of the precursors for IgG anti-tetanus antibody productionin vitro. Studies performed to determine the culture requirements of ^– and ⁺ cells revealed that production of IgG anti-tetanus toxoid antibody by both cell subsets was dependent on T cells and pokeweed mitogen. However, some ^– cells could produce IgG in the presence of T cells alone.     

Characterization of the suppressor activity in lymphocytes from patients with common variable hypogammaglobulinemia: evidence for an associated primary B-cell defect

The pathogenetic mechanisms responsible for the impaired immunoglobulin production in common variable hypogammaglobulinemia (CVH) are diverse with abnormalities in both B cells and immunoregulatory T cells. Production of IgG, IgM, and IgM-rheumatoid factor (IgM-RF) was measured in pokeweed mitogen (PWM) or Epstein-Barr virus (EBV)-stimulated cultures using various combinations of CVH, cord blood mononuclear cells (CBMC), and normal adult control B and T cells. The following results were obtained. First, the proportion of OKT3+ and OKT8+ cells were increased in CVH patients. Second, the T cells from four CVH patients and CBMC suppressed PWM-induced IgG, IgM, and IgM-RF production by normal B cells. Furthermore, major suppressor activity was found in the OKT8+ T-cell subpopulations in CBMC and three out of four CVH patients. There was no significant difference in relative suppression by OKT8+ cells from normal adults, CVH patients, or CBMC. However, in one CVH patient suppressor T cells were found in both OKT4+ as well as OKT8+ fractions. In the CVH patient with OKT4+ suppressor cells, X irradiation (1250 rads) abrogated suppressor activity and restored helper activity in the OKT4+ T-cell fraction. Irradiation of normal OKT4+ cells did not increase helper activity. When non-E-rosetting cells from normal subjects, CVH, and CBMC were stimulated with EBV it was observed that normal adult B cells could be induced to secrete IgG, IgM, and Ig-RF whereas CVH and CBMC could only produce IgM and IgM-RF but not IgG. The present study demonstrates for the first time that a radiosensitive OKT4+ suppressor cell is present in some CVH patients.     

The role of T cell--macrophage interactions in tuberculosis

Acquired resistance against tuberculosis paradigmatically depends on specific T lymphocytes and mononuclear phagocytes. The etiological agent,Mycobacterium tuberculosis is capable of replicating in mononuclear phagocytes which act both as habitat and as effectors of protection. Upon interaction with antigen-specific T lymphocytes infected mononuclear phagocytes acquire tuberculosis activities. Here, data from experimental tuberculosis studies in mice are summarized which show that: interleukins produced by cloned T cells and recombinant interferon- are capable of activating tuberculostatic capacities in macrophages; both CD4 and CD8 T cells, after adequate stimulation, produce interferon-; CD8 T cells lyse macrophages in an antigen-specific way; not only CD8 but also CD4 T cells possess an antigen-specific cytolytic potential; lysis of infected macrophages results in mycobacterial growth inhibition. Evidence is also presented that tuberculostatic activities of activated macrophages depend on phagosome-lysosome fusion and are independent of reactive oxygen metabolites and that some strains ofM. tuberculosis are resistant against interferon- activated macrophages. These findings suggest that both helper and cytolytic T cells participate in the immune response to tuberculosis and that similar T cell mechanisms contribute to resistance as well as pathogenesis. Protection against tuberculosis, therefore, depends on subtle coordination of the immune response.     

Regulatory roles of human OKT4/OKT8 subsets in polyclonal immunoglobulin production induced by herpes simplex type 1 virus

T cells, OKT4 cells and OKT8 cells from the peripheral blood of normal individuals seropositive for herpes simplex type 1 virus (HSV) were studied for their capacity to regulate in vitro polyclonal immunoglobulin (Ig) production induced by inactivated HSV. Polyclonal Ig production induced by HSV has been demonstrated to be T-cell dependent. T cells, OKT4 cells and OKT8 cells were co-cultured with autologous non-T cells in the presence of HSV or pokeweed mitogen (PWM) and the number of plaque-forming cells (PFC) was measured with an hemolytic plaque assay after 6 days of culture. The results in the HSV system show that the OKT4 cells provided significantly more helper activity than OKT8 cells (p = 0.002); and the OKT8 cells exhibited more suppressor activity than OKT4 cells for Ig production (p = 0.02). The helper activity of OKT4 cells after HSV stimulation was significantly less than that obtained after pokeweed mitogen stimulation (p = 0.01). The in vitro polyclonal immunoglobulin response to HSV antigen is regulated by the balance of helper/suppressor activity exerted by OKT4 and OKT8 cell subsets.     

Angioimmunoblastic T-cell lymphoma with autoimmune thrombocytopenia: A report of two cases

We report two patients, a 68-year-old man (Case 1) and a 66-year-old man (Case 2), with polyclonal gammopathy, lymphadenopathy, thrombocytopenia, and high platelet-associated IgG (PAIgG) level. We initially diagnosed them as having angioimmunoblastic lymphadenopathy with dysproteinemia (AILD). From confirmation of clear cells by careful observation and detection of rearrangement bands of T cell receptors by Southern blot hybridization analysis, we finally concluded that their diagnoses were compatible with angioimmunoblastic T-cell lymphoma (AILT). AILT with autoimmune thrombocytopenia (AIT) is very rare, and all the reported cases were Japanese ones.     

Interactions among human T cell subsets

TB and TT interactions involved in the regulation of human B cell differentiation were studied in vitro. The strategy employed here involved the isolation of OKT4⁺ and OKT8⁺ subsets and subsequent quantitative assessment of their effects on pokeweed mitogen (PWM) driven B cell differentiation as measured by the reverse hemolytic plaque assay. Thus, graded numbers of either untreated or irradiated OKT4⁺ and OKT8⁺ cell subsets were added to autologous B cells and after 6 days, cultures were assayed for plaque forming cells (PFC) activity.We found that the helper activity which is exclusively contained within the OKT4⁺ population is radiosensitive. Radioresistant OKT4⁺ helper cells could also be demonstrated but only at high T/B ratios. In contrast, the OKT8⁺ population is depleted of helper function and contains radiosensitive cells important in the suppression of B cell differentiation. However, the suppression observed with radiosensitive OKT8⁺ cells requires the presence of radiosensitive OKT4⁺ cells.Cooperative interactions between these subsets were further analyzed by investigating the immunoregulatory function of OKT4⁺ and OKT8⁺ cells in the induction of helper factor production in response to alloantigens. Evidence was obtained that the production of mixed lymphocyte culture (MLC) derived helper factor is dependent on OKT4⁺ cells but not OKT8⁺ cells. Furthermore, the alloantigen induced helper factor production and/or release was found to be suppressed by the radiosensitive OKT8⁺ subset.Finally, additional studies demonstrated that alloreactive as well as trinitrophenyl (TNP) altered-self reactive cytotoxic T lymphocytes (CTL) precursors are contained within the OKT8⁺ T cell subset. However, the killer cell activity was amplified by the presence of OKT4⁺ cells. This amplifying effect is mediated by factors released by OKT4⁺ cells after specific interaction with either soluble or alloantigens. These data, taken together, underscore the importance of functional TT interactions in the immunoregulation of both T and B cell differentiation.     

Phenotypic and functional characterization of a Sézary cell

We have studied the surface antigen pattern, enzymatic phenotype, and functional capacity of peripheral blood lymphocytes from a patient with Sézary syndrome (SS). The majority of these cells formed E rosettes but lacked the Fc() receptor. The neoplastic cells were reactive with pan-T cell (OKT3)- and helper T cell (OKT4)-subset monoclonal antibodies; however, they lacked the 5/9 antigen, which identifies a more restricted subset of helper T cells. Most SS cells also reacted with PTF 29.12, a monoclonal antibody which recognizes DR determinants. Only 35% of the cells expressed single, focal accumulations of -naphthyl-acid esterase activity, which is a characteristic of T._M cells, but 85% of them showed this focal staining pattern with acid phosphatase or -glucuronidase. Mononuclear cells from the SS patient showed poor or no proliferative response to phytohemagglutinin, pokeweed mitogen, concanavalin A, purified protein derivative, Candida, and allogeneic cells and lacked both helper and suppressor activity for pokeweed mitogen driven production of IgM and IgG immunoglobulins by normal B cells, but they were able to stimulate a marked proliferative response in mixed-lymphocyte culture. The defective expression of enzymatic and surface membrane characteristics, together with the lack of some T-cell functions, suggests that the patient cells may be immature T._M lymphocytes.     

Intravenous immunoglobulin induces interferon-γ and interleukin-6in vivo

Immunoglobulin is known to be an immunomodulator. It can induce protein mediators from mononuclear cells, particularly monocytesin vitro. Intravenous immunoglobulin (IVIg) has been used as a therapy in several clinical situations. In this study, the influence of IVIg infusion on the plasma levels of two protein mediators, interferon- (IFN-) and interleukin-6 (IL-6), was assessed in patients with secondary generalized epilepsy. Compared to preinfusion levels, plasma interferon- was increased in 18 of 18 patients 20 min after the 6- to 8-hr infusion of IVIg. Plasma interferon- levels reached their peak at various times from 20 min to 3 days post IVIg infusion, dependent upon the individual patient. Plasma IL-6 levels also increased after IVIg infusion. Generally, IL-6 reached its peak level after IFN-. No activated T cells or B cells were observed as determined by the expression of surface CD25, CD23, and HLA-DR 20 min following the infusion when the IFN- and IL-6 levels were assessed. The expression of the high-affinity receptor for IgG, CD64, on monocytes was significantly enhanced after IVIg infusion, while the low-affinity receptor for IgG, CD32, was only slightly increased. Cytoplasmic staining of PBMC indicates that both CD16-positive and CD16-negative cells may contribute to the increase seen in plasma IFN-. These data raise the possibility that the therapeutic effects of intravenous immunoglobulin may be related, at least in part, to the immunomodulatory activity as demonstrated by the changes in plasma levels of IFN- and IL-6.     

The effect of a single whole-blood transfusion on cytokine secretion

The effect of a single whole-blood transfusion on the cascade of cytokine secretion was studied in patients with chronic renal failure. The results indicate that 1 week after blood transfusion, no significant changes were observed in the secretion of interleukin-2, colony-stimulating factor, tumor necrosis factor, and -interferon. However, 2 weeks after blood transfusion, a sharp decrease was observed in the generation of these cytokines. A decrease of about 70% was observed in interleukin-2, tumor necrosis factor, and -interferon secretion. The production of colony-stimulating factor 2 weeks after blood transfusion amounted to about 30% less than baseline levels. No statistical differences in interleukin-1 production were observed throughout the study. In addition, we found that the decrease in cytokine secretion was paralleled by a sharp increase in thein vitro secretion of prostaglandin E₂. Thus the beneficial effect of blood transfusion on graft survival might be due in part to an immunosuppressive effect brought about by immuno-regulatory changes via the cascade of cytokine secretion.