人不同来源T细胞对丝裂原、PMA和A23187的反应性比较

本文比较了胎儿胸腺细胞、正常成人外周血Ｔ细胞及儿童扁桃体Ｔ细胞对丝裂原ＰＷＭ、ＰＨＡ和ＣｏｎＡ、ＰＫＣ激活剂ＰＭＡ和Ｃａ２＋导入剂Ａ２３１８７的反应性。结果表明：胎儿胸腺细胞对ＰＷＭ的反应对ＰＨＡ和ＣｏｎＡ的反应性很弱；正常成人外周血Ｔ细胞对ＰＨＡ的反应性最强，对ＰＷＭ和ＣｏｎＡ的反应性较弱；儿童扁桃体Ｔ细胞对３种丝裂原的反应性均很强；ＰＭＡ单独作用能强烈诱导儿童扁桃体Ｔ细对正常成人外周血Ｔ细胞及胸腺细胞作用较弱；ＰＷＭ和ＰＭＡ对胎儿胸腺细胞及正常成人外周血Ｔ细胞均有明显协同作用，但对儿童扁桃体Ｔ细胞无协同作用；Ａ２３１８７单独作用对３种Ｔ细胞的增殖作用均很弱，Ａ２３１８７对ＰＷＭ诱导的增殖均有部分抑制作用。这些结果对于认识处于不同发育阶段及不同部位的的活化途径和功能有一定意义。     

Effect of PHA-activated T cells on B-cell differentiation.

Recent studies indicate that human T cells expressing the T4 determinant are comprised of functionally distinct subsets. We investigated if activation of OKT4+ cells with the mitogen PHA affected their ability to regulate the proliferation and polyclonal differentiation of autologous B cells. OKT4+ cells were preactivated with PHA and then cocultured with autologous B cells in the presence or absence of PWM. B-cell proliferation and differentiation to immunoglobulin-secreting cells (IgSC) were assessed by [3H]thymidine incorporation and reverse haemolytic plaque assay, respectively. In the absence of PWM, the PHA-activated OKT4+ cells demonstrated radioresistant help and radiosensitive suppression of IgSC responses. Addition of PWM to cocultures of irradiated PHA preactivated OKT4 cells and autologous B cells resulted in further suppression of IgSC responses, suggesting that PWM activated yet another suppression mechanism. Addition of PWM caused diminished B-cell proliferation as well. These data demonstrate functional heterogeneity within the OKT4 subset, and suggest that the particular immunoregulatory activity displayed is influenced by the state and mode of activation of these cells.     

Modulation of T and B Cell Proliferative Responses by Factors Present in Rat Salivary Glands

Rat salivary gland culture supernatants (SGSN) were shown to inhibit the proliferation of rat spleen cells induced by the mitogens concanavalin A (ConA), phytohaemagglutinin (PHA), pokeweed mitogen (PWM), lipopolysaccharide (LPS) and S. typhimurium mitogen (STM). The responses of B cells were more markedly inhibited than the responses of T cells. Factors contained in SGSN which had a molecular weight smaller than 3500 inhibited all responses, whereas factors greater than 3500 only inhibited responses induced by PWM, LPS or STM. Factors present in SGSN also inhibited the proliferation of two B cell hybridoma cell lines, as well as the IL-2-responsive cell line CTLL-2 and the IL-4-responsive cell line CT.4S. However, SGSN factors having a molecular weight greater than 3500 did not inhibit CTLL-2 proliferation. These data indicate that rat salivary glands contain factors which differentially regulate T and B cell proliferative responses in vitro and which may modulate localized immune responses in the salivary gland in vivo.     

Study on the Effect of Calf Thymic Peptides Preparation (Tp) on Human B' Lymphocytes

Extensive experimental evidence has shown that thymic hormones (or factors) affect and regulate the differentiation and function of T lymphocytes. However, little is known about the action, if any, of thymic hormones on B lymphocytes. This paper reports the results of an investigation of the effect of a calf thymic peptide preparation (TP) prepared in our laboratory, on the proliferation and differentiation of human B lymphocytes.

TP at concentrations higher than 1 μg (protein)/ml inhibited the proliferative responses of human B lymphocytes to the stimulation by Staphylococcus aureus Cowen strain I (SAC) and F(ab')₂ fragments of goat anti-human IgM μ chain specific antibody (anti-μ). TP itself had neither toxic nor mitogenic effect on B cells. TP at concentrations of 60 and 100 μg/ml did not affect the differentiation of B cells driven by SAC and PWM in a reverse PFC assay, but appeared to suppress the production in some individuals of total IgG and IgM in culture supernatants in a PWM system. Preculture of B cells with 60 μg/ml of TP for 40 hrs showed a suppression of the proliferative response to SAC and anti-μ stimulation, suggesting that TP might act on cells directly and persistently for some time. When TP was added to the culture on day 0 or on day 1, a similar decrease of inhibition of B cell proliferation was observed. A decrease in monocytes from 15-17% to 5% did not appreciably influence the suppression of SAC-or anti-μ-induced proliferation of B cells by TP. These preliminary results suggest that a calf thymic peptides preparation might have some direct effect on B lymphocytes.     

Klebsiella pneumoniae stimulate highly purified human blood B cells to mature into plaque forming cells without prior proliferation.

The plaque forming cell (PFC) and proliferative responses of human peripheral blood lymphocytes and highly purified blood B cells induced by pokeweed mitogen (PWM) and group A streptoccocal cell membranes (A-ScM) were compared with the responses triggered by various cell preparations of Klebsiella pneumoniae K 43 (Klebs). The number of PFC was determined by a protein A plaque assay, and lymphoproliferation was measured by 3H-thymidine incorporation. In cell cultures stimulated with PWM and A-ScM, lymphocyte proliferation appeared to be associated with the generation of PFC. Klebs caused development of PFC without measurable prior proliferation. Whereas the response to PWM and A-ScM was absolutely T cell-dependent, highly purified B cells generated PFC when incubated with Klebs. Moreover, restitution of T cells to the B cell fraction did not augment (or diminish) the number of plaques. These studies establish that Klebs cell envelope structures contain a T cell-independent polyclonal B cell activator for human B lymphocytes in a high stage of differentiation. Use of this probe should provide further insight into the cellular interactions involved in the differentiation of antibody forming cells in humans.     

Modulation of T and B Cell Proliferative Responses by Factors Present in Rat Salivary Glands

Rat salivary gland culture supernatants (SGSN) were shown to inhibit the proliferation of rat spleen cells induced by the mitogens concanavalin A (ConA), phytohaemagglutinin (PHA), pokeweed mitogen (PWM), lipopolysaccharide (LPS) and S. typhimurium mitogen (STM). The responses of B cells were more markedly inhibited than the responses of T cells. Factors contained in SGSN which had a molecular weight smaller than 3500 inhibited all responses, whereas factors greater than 3500 only inhibited responses induced by PWM, LPS or STM. Factors present in SGSN also inhibited the proliferation of two B cell hybridoma cell lines, as well as the IL-2-responsive cell line CTLL-2 and the IL-4-responsive cell line CT.4S. However, SGSN factors having a molecular weight greater than 3500 did not inhibit CTLL-2 proliferation. These data indicate that rat salivary glands contain factors which differentially regulate T and B cell proliferative responses in vitro and which may modulate localized immune responses in the salivary gland in vivo.     

Stimulated proliferative responses in vertically HIV-infected children on HAART correlate with clinical and immunological markers

The objective of the study was to investigate the relationship between various CD4+ T cell subsets and the ability of peripheral blood mononuclear cells (PBMC) to proliferate to several stimuli in vertically human immunodeficiency virus type 1 (HIV-1)-infected children. We studied 29 HIV-1-infected children on highly active antiretroviral therapy (HAART) (median duration: 12.3 months). T cell subsets were determined by flow cytometry. Plasma viral load (VL) was quantified using a standardized molecular method. Proliferative responses were evaluated by [3H]-thymidine incorporation. Decreased proliferative responses of PBMC to pokeweed mitogen (PWM) were found for HIV-1-infected children in Centers for Disease Control (CDC) clinical categories B and C when compared to the control group (P < 0.05). Similarly, children with < or = 15% CD4+ T cells showed a decrease in proliferative responses to PWM (P < 0.01), anti-CD3 + anti-CD28 (P < 0.01) and phytohaemagglutinin (PHA) (P < 0.05) with respect to the control group and to children with CD4+ T cells > or = 25%. Proliferative responses to PWM, anti-CD3+, anti-CD28 and PHA had a statistically significant positive correlation with CD3+/mm3, CD4+/mm3, % CD4 T cells, CD4/CD8 ratio and the percentage of naive T cell subsets (CD4+CD45RO-HLA-DR-, CD4+ CD45RA+ CD62L+, CD4+ CD45RA+), CD4+ CD62L+ and CD4+ T cells co-expressing CD38+ (CD4+ HLA-DR-CD38+, CD4+ CD38+). Moreover, we found a negative correlation between PBMC proliferative responses and % CD8 T cells, memory, memory-activated and activated CD4+ T cell subsets. Lower proliferative responses to PWM (P < 0.01) and PHA (P < 0.01) were associated with higher VL. Our data show that higher proliferative responses to PWM, anti-CD3 + anti-CD28 and PHA are associated with both non-activated and naive CD4+ T cell subsets in HIV-1-infected children on HAART.     

Mitoxantrone induces cell death in peripheral blood leucocytes of multiple sclerosis patients

Mitoxantrone (MX) is a cytotoxic drug with proven clinical efficacy in active multiple sclerosis (MS). In this ex vivo study we investigated the immunological effects of MX on peripheral blood leucocytes (PBL) from MS patients. PBL were isolated from 46 patients with active MS (mean age 42 years, female : male 1.4 : 1) before and immediately after 1 h MX infusion. Isolated PBL were cultured and stimulated with phytohaemagglutinin (PHA), T cell receptor stimulating monoclonal antibody (MoAb) X35 or kept in culture medium alone. Proliferation was measured by [3H]-thymidine incorporation. MX-uptake and cell death in PBL subpopulations was analysed by flow cytometry using antibodies against cluster of differentiation (CD)-surface antigens, annexin V (AnnV) and propidium iodide (PI). MX was incorporated rapidly into PBL. After only a 1-h in vivo exposure, MX reduced proliferative responses in unstimulated and stimulated PBL (PHA: - 17%, MoAb X35: -13%). MX-exposed PBL showed an increase of AnnV+/PI+ cells (unstimulated: 12%, PHA: 15%), which was even more pronounced 2 weeks after infusion. No difference was observed between de novo MX-treated patients and those on long-term MX treatment. In T cell receptor stimulated PBL, cell death was induced preferentially in CD19-positive B cells and to a lesser extent in CD8-positive T cells. MX is incorporated rapidly in circulating PBL of MS patients and induces a pronounced suppression of proliferative responses. This suppression appears to be mediated at least partly by the induction of late apoptotic/necrotic cell death with a preferential susceptibility of B cells.     

5-bromodeoxyuridine-light inactivation of human lymphocytes stimulated mitogens and allogeneic cells: evidence for distinct T-lymphocyte subsets.

The study of human peripheral blood currently permits enumeration of circulating B and T lymphocytes as well as the analysis of functional responses in vitro following stimulation with mitogens, antigens or allogeneic cells. In the present experiments, subsets of these major lymphocyte populations were analyzed by dissecting in vitro responses using an ablative technique. After an initial culture period of lymphocytes with a mitogen, the proliferating cells were inactivated with 5-bromodeoxyuridine and light, then the capacity of the remaining lymphocytes to respond to the same or a different mitogenic influence was tested. Responsiveness to a different stimulant in the presence of no further response to the first stimulant was taken as evidence for a different responding cell population. A large subset of peripheral blood lymphocytes was responsive to both phytohemagglutinin (PHA) and concanavalin A (Con A); ablation of the cells responsive to one left little or no cells responsive to the other. Pokeweed mitogen (PWM) stimulated a portion of the PHA-Con A-responsive subset and an approximately equal subset unresponsive to PHA or Con A. Other evidence indicates that with each of these mitogens (especially with PHA and Con A in a soluble form), most of the proliferative response of peripheral blood B lymphocytes is indirectly triggered and is dependent on T cell stimulation. The population of PHA-Con A-responsive cells is, therefore, interpreted to represent a major T cell subset plus recruited cells; the PWM-responsive population would include a T cell subset having also PHA and Con A responsiveness, and another subset of T (or perhaps B) cells. The mitogen-sensitive population showed no overlap with cells responsive to allogeneic stimulation in mixed leukocyte culture. Ablation of the mitogen-responsive cells potentiated the mixed leukocyte reaction, suggesting that a suppressive influence was removed with the inactivation of the mitogen-responsive cells. It appears, therefore, that distinct subsets of T lymphocytes differentially responsive to PHA-Con A, to PWM and to allogeneic stimulation are present in the human peripheral blood.     

Interleukin-4 suppresses immunoglobulin production by peripheral blood lymphocytes of patients with common variable immunodeficiency (CVI) induced by supernatants of T cell clones.

Supernatants of both CD4+ and CD8+ alloreactive T cell clones induced IgM, IgG and IgA synthesis by peripheral blood lymphocytes (PBL) of healthy donors in vitro. These supernatants were also tested on their capacity to induce immunoglobulin production by PBL of four patients with CVI and one patient with CVI and thymoma. A low degree of IgM, IgG and IgA production was induced in one patient with CVI. In the patient with CVI and thymoma, induction of IgG and IgA synthesis was in the normal range, whereas IgM production was reduced. In the three other patients only a low production of IgM was induced. Interestingly, pre-incubation of the PBL for 24 h with interleukin-4 (IL-4) suppressed immunoglobulin production both by PBL of the patients with CVI and healthy donors. The strongest inhibitory effects were observed on IgA synthesis. These data indicate that B cells of three patients with CVI can not be induced to switch to IgG or IgA producing cells in vitro. In contrast, B cells of the patient with CVI and thymoma were able to respond to the relevant B cell growth and differentiation factors present in the T cell clone supernatants, suggesting that the T cells of this patient may fail to produce these factors. However, the proliferative responses of the T cells to phytohaemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM), were normal in all five patients tested. In addition, the interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) production by PBL of the five patients was also in the normal range. Although only a small number of patients was tested, these results support the view that defects in both regulatory T cell functions and/or intrinsic B cell defects may contribute to the pathogenesis of CVI.     

Characterization of Human CD4+ T-Cell Clones that Secrete Helper Factor(s) for B-Cell Proliferation and Maturation

Human peripheral blood lymphocytes (PBL) were activated with K46M, a m mitogenic monoclonal antibody against La-reactive T lymphocyte surface structures. The cultures were expanded in the presence of interleukin 2 (IL-2). After 1 month of culture, the activated T cells were cloned by limiting dilution at 0.5 cells/well. Five clones with the CD3+CD4+ phenotype and one clone with the CD3+CD8+ phenotype were obtained. The CD3+CD8+ clone (K99) displayed a strong major histocompatibility complex (MHC)-unrestricted cytolytic activity against MOLT-4 and a weaker reactivity against the bladder tumour cell lines T24 and RT4. The natural killer (NK)-susceptible K562 cells were not lysed. Two of the CD3+CD4+ clones (K91 and K914) showed a helper activity in pokeweed mitogen (PWM)-induced IgG production by B cells. These cells differed in the expression of CD45R and CDw29 antigens, as defined by the monoclonal antibodies 2H4 or D10D11 and 4B4. When stimulated with PWM for 48 or 72 h, clone K91 and an additional CD4-positive clone (K913) secreted a factor into the supernatants which helped B cells to produce IgG. The K913 supernatant also induced some IgM production. The supernatant obtained after similar stimulation of K914 cells was inactive. None of these supernatants induced B cells to proliferate when tested together with phorbol myristate acetate (PMA). However, when K91 and K914 cells were activated with phytohaemagglutinin (PHA) for 48 or 72 h, the supernatant from K91 was strongly helpful in B-cell proliferation, whereas the supernatant from K914 cultures was only moderately active. In conclusion, we have established human T helper clones that release different factors supporting either B-cell proliferation or maturation when stimulated with PWM or PHA.     

Immunomodulating properties of the uremic pentapeptide H-Asp-Leu-Trp-Glu-Lys-OH in vitro

Summary A pentapeptide originally isolated by Abiko and coworkers from the ultrafiltrate of a uremic patient was synthesized and studied for its in vitro effects on normal human peripheral blood mononuclear cells. The SRBC-rosette forming capacity of T cells was significantly reduced after preincubation of the cells with the peptide, whereas the viability and the percentage of SRBC-receptor positive cells as determined with a monoclonal antibody remained unchanged. The PHA and ConA induced proliferation of T cells as well as the induction of suppressor cells by ConA were decreased, while the proliferative responses to PWM and specific antigens were enhanced. MLC experiments with separated and reconstituted lymphocyte populations pointed to the T cell as the main target. The data presented demonstrate that at least some of the effects described for so-called middle molecules are reproducible with this peptide at concentrations eventually occurring in patients with chronic renal failure.Abbreviations cpm counts per minute - ConA Concanavalin A - HPLC high performance liquid chromatography - LTT lymphocyte transformation test - MLC mixed lymphocyte culture - PBL peripheral blood lymphocytes - PHA-P,M phythemagglutinin P,M - PPD purified protein derivative - PWM pokeweed mitogen - SRBC sheep reed blood cells - U5P, U5-peptide uremic pentapeptide This work was supported by grants from the Deutsche Forschungsgemeinschaft (Ni 233/1-1) and the Robert-Pfleger-Stiftung     

Functional properties of continuously cultured human T lymphocytes.

Human T lymphocytes (CCTC) have been maintained in continuous culture by a new method. The ability of CCTC to produce three types of T cell response has been determined and compared to the published responses of T cells grown in 'T cell growth factor' (TCGF) medium. Unlike TCGF cells, CCTC will not give proliferative responses when stimulated with PHA, Con A, or allogeneic lymphocytes even when supplemented with autologous PBL as a source of accessory cells. Instead, CCTC are potent inhibitors of the proliferative response of normal cells in MLC. This suppressive activity is not specific for histocompatible cells. Finally, CCTC express cytotoxic activity to a number of human lymphoid cell lines and this activity appears to be different from the polyclonal cytotoxicity reported for TCGF-maintained cells. Our method of long-term T cell culture therefore appears to grow cells with different properties from TCGF cells.     

An analysis of the growth and differentiation of B cells isolated from follicles of the ileal Peyer's patch of sheep.

We developed a method to isolate and culture cells from the lymphoid follicles of the ileal Peyer's (PP) patch of young sheep (6-12 weeks). These cells were 98% sIgM+ B cells and 1% T cells. Cultured follicular cells were used to investigate B-cell proliferation and differentiation. Less than 50% of B cells were viable after 24 hr of culture and this decrease in B-cell viability also occurred following co-stimulation with pokeweed mitogen (PWM) and recombinant bovine interleukin-1 (rBoIL-1) or rBoIL-2. In contrast, co-stimulation with PWM and either rBoIL-1 or rBoIL-2 induced a marked proliferative response that was maximal on Day 4 of culture. Cytokine-induced proliferation of the B cells required PWM co-stimulation and proliferation induced by rBoIL-1 and rBoIL-2 was neither additive or synergistic. This suggests that PWM bound a molecule or molecules that signalled responsiveness to both rBoIL-1 and rBoIL-2. Culture of follicular cells with PWM and both rBoIL-1 and rBoIL-2 also resulted in B-cell differentiation. This differentiation was associated with decreased proliferation, an increased number of viable B cells, and increased expression of both surface IgM and non-Ig membrane molecules. Thus, co-stimulation of ileal PP follicular cells with PWM and rBoIL-1 and rBoIL-2 resulted in both B-cell proliferation and differentiation.     

Alloproliferative human T cell clones primed and cultured in vitro lose proliferative and gain suppressive activity with age

Alloreactive human T lymphocyte clones were found to lose antigen-stimulated proliferative capacity and their ability to secrete interleukin 2 (IL 2) after a critical period in tissue culture. Instead, they gained the previously absent capacity to suppress lymphoproliferative (LP) responses in the presence or absence of exogenous IL 2. Such "ex-PLT" suppressive clones continued to grow perfectly well, retaining IL 2 and filler cell dependency, apparently normal karyotypes, and their OKT4+, OKT8- phenotypes. At least two suppressive mechanisms were demonstrated: (1) the "induction" of suppressive effectors in normal peripheral lymphocytes, and (2) a direct suppressive activity on lymphocyte proliferation shown by their ability to inhibit restimulation of cloned lymphocytes lacking suppressor cell precursors. The consistent "differentiation" from IL 2-secreting "helper" status to nonspecific suppressive status may represent a novel immunoregulatory phase in the long-term differentiation of normal human T cells.     

Stimulation of chronic lymphatic leukaemia cells by pokeweed mitogen after treatment with neuraminidase-galactose oxidase.

CLL lymphocytes gave a low response upon stimulation with PHA or PWM in 3-day cultures. However, after treatment with neuraminidase-galactose oxidase (NGO), in the presence of PWM, CLL lymphocytes transformed into blasts and incorporated 3H-thymidine in 3-day cultures. This response of CLL lymphocytes was similar to that given by normal lymphocytes to PWM in 3-day cultures. The best stimulation of CLL lymphocytes was achieved when conditioned medium (CM) from normal T lymphocytes was present in PWM cultures. Purified B lymphocytes from CLL (T lymphocytes and monocytes removed) did not respond to PHA or PWM. However, after NGO treatment these cells were stimulated by PWM, but only in the presence of CM. PHA failed to stimulate NGO-treated CLL lymphocytes or purified B lymphocytes. This study shows that CLL lymphocytes, which usually fail to respond to mitogens, can be stimulated by PWM to proliferate after treatment with neuraminidase-galactose oxidase (NGO). This technique of B cell stimulation has been found useful in cytogenetic studies of B cell proliferative disorders.     

Induction of Proliferation and Differentiation of Leukaemic B Cells from Patients with Chronic Lymphocytic Leukaemia by Anti-μ and Conditioned Medium

We investigated the growth and differentiation of leukaemia B cells from patients with B-cell chronic lymphocytic leukaemia (CLL) in response to proliferation and differentiation factors present in conditioned medium and to anti-immunoglobulin antibodies. Highly purified E-rosette negative (E-) B cells from 5 out of 15 patients with CLL exhibited moderate proliferative responses to 10 or 50 micrograms/ml of F(ab)'2 fragments of rabbit anti-human mu-chain specific antibody. Conditioned medium (CM), derived by stimulating human peripheral blood mononuclear leucocytes with PHA, induced significant proliferative responses of purified E- cells in 13 out of 14 patients examined. The extent of these proliferative responses varied substantially, and was in the range of 2.6- to 91-fold. Stimulation of purified E- cells from patients with CLL with both anti-mu and CM resulted in significant proliferation in all 15 patients examined. These responses were significantly higher than those induced by CM alone (P less than 0.02). Synergism between CM and anti-mu in inducing proliferative responses was observed in 11 out of 15 patients. Largely leukaemic B cell populations expressing on the cell surface more than one immunoglobulin heavy-chain isotype, exhibited significantly higher (P less than 0.009) proliferative response to CM and anti-mu than those expressing IgM only. Highly purified E-peripheral blood or tonsil lymphocytes from all normal donors examined responded by proliferation to anti-mu alone or to CM alone. Synergism in inducing proliferative responses was also observed when the cells were stimulated with both CM and anti-mu. In addition to inducing proliferative responses, culture with CM of purified E-rosette negative, largely leukaemic, B cells from patients with CLL for 6 days at 37 degrees C resulted in differentiation into immunoglobulin synthesizing and secreting cells. Synthesis and secretion of IgM were observed in 7 out of 10 patients examined. A switch to IgG production was observed in three patients. Morphological examination of E- cells from patients with CLL after treatment with CM demonstrated that these cells were differentiated into plasma-like cells. These results suggest that leukaemic B cells from patients with CLL can be induced to proliferate and differentiate in response to growth and differentiation factors derived by mononuclear leucocytes, in a manner similar to that of normal B cells.     

The in vivo and in vitro effects of caffeine on rat immune cells activities: B, T and NK cells

The effect of caffeine (naturally occurring plant methylxanthine) on immunological cell activities in Sprague-Dawley rat both in vivo and in vitro was studied. A cytotoxic assay was done to study natural killer (NK) cells and a proliferation assay was performed for T and B cell activities. Three different doses of caffeine i.e., 2, 6 and 18 mg/kg/day were administered chronically to Sprague-Dawley rats to assess the effects in vivo. Both NK cell cytotoxicity and B cell proliferative response to pokeweed mitogen (PWM) showed significant decreases (P less than 0.05) in rats treated with 6 mg/kg/day, whereas the T cell proliferative response to phytohemagglutinin-P (PHA-P) was significantly increased (P less than 0.05) in the rats treated with 18 mg/kg/day. In vitro, caffeine significantly decreases (P less than 0.05) B and T cell proliferative responses to PWM and PHA-P at added caffeine concentrations of 10, 20 and 40 micrograms/ml. However, no effect was observed on NK cells activity. Furthermore, in vitro, a broader dose range of caffeine (1, 10, 100 and 1,000 micrograms/ml) exhibited dose-dependent inhibition of both B and T cell proliferative responses.     

Lymphocyte proliferative responses in haemophiliac patients: relations to clinical and immunological findings

Blood lymphocyte proliferative responses to mitogens were studied in 65 patients with haemophilia (haemophilia A: 54 patients, haemophilia B: 11 patients) in parallel with 39 male control subjects. As a group, patients with haemophilia did not demonstrate abnormal proliferative responses to phytohaemagglutinin (PHA), Concanavalin A (ConA) and pokeweed mitogen (PWM) when compared with healthy controls. When the patients were analysed according to their seropositivity for antibody to human immunodeficiency virus (HIV), those who were positive had significantly decreased PHA, ConA and PWM responses. Haemophiliac patients with T4+/T8+ ratios less than 1 had reduced proliferative responses to PHA, ConA and PWM when compared to patients with ratios greater than 1. No significant difference in mitogen responses were found when the patients were analysed according to the presence or absence of palpable lymphadenopathy. Those patients with haemophilia A who had received more than 5 x 10(4) units of factor VIII during the two years preceding the study showed no significant difference in PHA, ConA and PWM responses when compared to patients receiving less.     

Human B cell function in responder and non-responder individuals. II. The role of T helper cells in promoting the PWM-induced B cell production of immunoprotein

Sorted OKT4+ cells treated with pokeweed mitogen (PWM) and subsequently X-irradiated were used as a source of helper T cells to examine human T and B cell function. PWM-induced immunoprotein synthesis by human peripheral blood lymphocytes was the model used to study the cellular interactions. PWM was shown to induce helper T cell function which caused non-PWM treated B cells to secrete immunoglobulin. PBL from certain individuals could not be induced by PWM to secrete Ig therefore allogeneic co-cultures of helper T cells and B cells were examined to define the defective cell population. Ig synthesis in allogeneic cultures of T and B cells was always greater than that observed in autologous cultures when cells from responders were assayed. However, when allogeneic cultures were initiated using B cells from a responder and PWM treated T cells from a non-responder and examined for Ig synthesis, the B cell responses were markedly lower than seen in the autologous responder cultures. In addition, PWM activated helper T cells from a responder induced a significantly higher Ig synthesis by B cells from a non-responder. These observations indicate that PBL from individuals who do not respond in a PWM driven Ig synthesis assay have relatively normal B cell function but are deficient in helper T cell function.