Human T cells in cord blood: abnormalities in IA antigens induction by phytohemagglutinin and in autologous mixed lymphocyte reactions

Immune status of newborns in perinatal chlamydial infection

PROBLEM

Thirty newborns, delivered by mothers with urogenital chlamydiosis, diagnosed on the 35th-36th weeks of gestation, and 10 newborns of healthy mothers were studied immunologically. CD3 (T-lymphocytes), CD19 (B-lymphocytes), CD4 (T-helpers-inductors), CD8 (T-suppressor-cytotoxic), T-lymphocyte response to PHA, levels of Ig G, A, M in umbilical blood were detected.

METHOD

Chlamydia trachomatis antibody's titers in umbilical blood were determined by indirect immunofluorescent method (with antigen C. trachomatis, serovar L2). Antibody titers found in umbilical blood were in 50% of cases higher than antibody level in mother's blood serum, and they later varied from 1:64 to 1:256. It was established that newborns delivered by mothers with urogenital chlamydiosis had imbalance of T-lymphocyte subsets, decrease in the numbers of T- and B- lymphocytes, and increased level of Ig M, while the level of Ig G did not change significantly. The exposed disproportion in immune status neonatal, born from mothers with urogenital chlamydiosis, in combination with high C. trachomatis antibody titers in umbilical blood may be prognostic of the development of neonatal chlamydial infections.

Identification of a cord blood T cell subset of CD3+4-8-45R+ suppressing interleukin 2 production in the autologous mixed lymphocyte reaction and the mode of action of exogenous IL2 in the induction of IL2 production

As previously reported, the inability of cord blood T cells to produce IL2 in the autologous mixed lymphocyte reaction (AMLR) could be recovered by the treatment of stimulator non-T cells with interferon-gamma (IFN-gamma) and of the AMLR with exogenous IL2. In the present study, we showed that addition of untreated autologous cord blood T cells to the above-mentioned AMLR abrogated the IL2 production in a dose-dependent manner, suggesting active suppression by the untreated T cells because untreated cord blood T cells did not consume IL2. Suppressor activity was abrogated by the treatment of cord blood T cells with monoclonal anti-CD3 antibody plus complement or with monoclonal anti-CD45R (Leu 18) antibody, but not by the treatment with monoclonal anti-CD4 antibody and/or anti-CD8 antibody plus complement. These data showed that the cord blood suppressor T cells were CD3+4-8-45R+. This suppressor activity also disappeared by culturing with rIL2 for 8 hr. As the frequency of CD45R+ cord blood T cells was comparable to that of CD45R+ adult T cells and was minimally affected by the IL2 treatment, functional modulation of CD45R+ suppressor T cells by IL2 is suggested. Moreover, in spite of the inhibitory effect of anti-CD45R antibody on the suppressor activity, IL2 production was not induced merely by addition of anti-CD45R antibody directly to the responder cells in AMLR. Taken together, these data suggest the requirement of exogenous IL2 for IL2 production in that IL2-producing-precursor T cells themselves should be stimulated by IL2 in addition to the modulation of CD45R+ suppressor T cells by IL2.

Expression of HLA-class II antigens and proliferative capacity in autologous mixed lymphocyte reactions of human T lymphocytes exposed in vitro to alpha-endorphin

alpha-Endorphin (aEP) inhibited the expression of HLA-Class II antigens by PHA-primed T lymphocytes and reduced mitogen-induced T-cell proliferation up to 35%. This action was time related and not naloxone sensitive. When aEP was added to autologous and allogeneic lymphocyte cultures (both of non-T/T and T/T type), it inhibited lymphocyte blastogenesis up to 40%. These findings, indicating that aEP can influence some functions of immunocompetent cells, provide evidence for the functional interrelationship between the neuroendocrine and the immune systems.

Neonatal T4+ lymphocytes: analysis of the expression of 4B4 and 2H4 antigens

Using monoclonal antibodies anti-2H4 and anti-4B4 we investigated by double immunofluorescence and immunorosette technique the presence of cells displaying the helper-inducer and the inducer of suppression phenotype among T4+ cord blood cells. The analysis of the estimated frequencies of subpopulations of T4+ cells shows that a high percentage of T4+ cord blood cells can coexpress both antigens in comparison to adult. Furthermore the percentage of T4+ cells with helper-inducer phenotype (2H4-4B4+) is significantly lower than that in the adult, while the percentage of T4+ cells with suppressor-inducer phenotype (2H4+4B4-) although higher, is not significantly different. These findings suggest that the relative immunoincompetence observed in the newborn may result from a variety of mechanisms including a low percentage of helper-inducer (4B4+2H4-) T4+ lymphocytes possibly also associated to an increased number of suppressor-inducer T4+ cells (2H4+4B4-).

Thymic hormone modulation of CD38 (T10) antigen on human cord blood lymphocytes

We studied the in vitro effect of three different thymic factors on the expression of CD38 (T10) antigen on cord T-lymphoid cell surface. The results showed that cord mononuclear cell populations contain variable percentages of CD38+ cells. The CD38 molecule was expressed on cord T and B lymphocyte and monocyte surfaces. Incubation with thymic agents induced a significant increases in the CD38+ cell percentage only in the samples with low CD38 antigen expression, and this modulation was mainly attributable to the T-cell subset. The effect seems to be specific and not correlated with the known high spontaneous DNA synthesis rate of cord mononuclear cells.

T cells from patients with chronic liver diseases: abnormalities in PHA-induced expression of HLA class II antigens and in autologous mixed-lymphocyte reactions

The expression of HLA Class II antigens by resting and phytohemagglutinin (PHA)-activated T cells and their functional properties in autologous mixed-lymphocyte reactions (MLR) were investigated in patients with chronic active hepatitis, with alcoholic cirrhosis, and with primary biliary cirrhosis. In all groups of patients the percentage of resting T cells expressing HLA Class II antigens was significantly higher than that in controls. The percentage of T cells which acquired HLA Class II antigens following PHA stimulation was reduced in patients with chronic active hepatitis, serum hepatitis B surface antigen (HBsAg) positive, and in those with alcoholic cirrhosis, HBsAg negative, although the level of [3H] thymidine incorporation was within normal limits. The degree of proliferation in autologous MLR with PHA-T cells was significantly reduced in patients with chronic active hepatitis, HBsAb positive, and in those with alcoholic cirrhosis, HBsAg positive. A reduced proliferation was also detected in autologous MLR with non-T cells, in patients with chronic active hepatitis, HBsAg positive. The abnormalities of autologous MLR are selective, since the proliferative and stimulatory activities of cells from patients with chronic liver diseases in allogeneic MLR were within normal ranges. The immunoregulatory role of HLA Class II antigens and of autologous MLR suggests that the abnormalities we have identified may play a role in the immunological dysfunctions underlying chronic liver diseases.

PHA-T cells in systemic lupus erythematosus and in rheumatoid arthritis: abnormalities in HLA class II antigen induction and in autologous mixed lymphocyte reactions

Analysis of T cells from patients with systemic lupus erythematosus (SLE) and with rheumatoid arthritis (RA) identified a deficit in the induction of HLA Class II antigens by PHA although the proliferative response was normal and in the [3H]thymidine incorporation in autologous mixed lymphocyte reactions (MLR) with PHA-T cells as stimulators. In RA these abnormalities were more marked in patients with active disease than in those in clinical remission. The deficit of autologous MLR with PHA-T cells was more marked than that of autologous MLR with non-T cells and of allogeneic MLR. Serum from patients with SLE and with RA did not display any detectable inhibitory activity on the induction of HLA Class II antigens by PHA, on the proliferative response of lymphocytes to PHA, on autologous MLR with PHA-T cells and with non-T cells as stimulators and on allogeneic MLR. These results suggest that the abnormalities we have identified reflect an intrinsic defect of T cells.

Circadian variations of autologous mixed lymphocyte reactions and endogenous cortisol

The degree of proliferation of human T cells stimulated with autologous PHA-T cells and with autologous non-T cells displays circadian variations. The highest proliferation occurs with cells isolated from blood drawn at 8 a.m. in mixed lymphocyte reactions (MLR) with autologous PHA-T cells and from blood drawn at 8 p.m. in MLR with autologous non-T cells. The circadian variations of autologous MLRs appear to reflect changes in the proliferative response of T cells. In autologous MLRs with non-T cells as stimulators the extent of proliferation was inversely correlated with the level of endogenous cortisol. The circadian variations of autologous MLRs do not reflect non-specific changes in the proliferative and stimulatory properties of T and non-T cells, since circadian variations were not observed in the proliferative response of T cells to mitogens and in allogeneic MLRs. Circadian variations of autologous MLRs must be taken into account when analyzing abnormalities of these reactions in pathological conditions.

Immature T lymphocytes in human neonatal blood

Thirty-two cord blood samples taken after caesarean section or vaginal delivery and concurrent venous blood samples obtained from normal adult controls were evaluated using monoclonal antibodies. The percentage of circulating pan-T-cell+ lymphocytes was significantly lower in cord blood (46%) compared with adult controls (72%). In the cord cells, 22% showed reactivity with the common thymocyte antigen compared with less than 1% in adult controls. The helper:suppressor ratio was lower in cord blood (1.71) compared with 1.98 for adult blood. These figures reflect a unique population (12%) of immature T cells in cord blood that coexpress helper and suppressor phenotypes. These features are not found in adult blood. These double-labeling studies characterized a previously undescribed blood T-cell phenotype which correlates negatively with gestational age (R = -0.93). These studies reveal the presence of an immature population of T cells in normal human neonatal blood that exhibit the phenotype characteristic of normal developing thymocytes.