Functional subsets of human T cells defined by "active" rosette formation

Effect of ribonuclease from Bacillus intermedius on human blood lymphocytes

By using a rosette formation test the effect of ribonuclease Bacillus intermedius (RNase Bi) on T- and B-lymphocytes in human peripheral blood has been studied in vitro. The RNase effect on T-lymphocytes depends on its concentration: low concentrations (10(-6)-10(-2) microg ml(-1)) stimulate E-rosette formation whereas high concentrations (10 microg ml(-1)) suppress it. The amount of B-lymphocytes decreases under RNase Bi influence in all concentrations tested. RNase Bi like thymus hormones influence immature lymphocytes (0-cells) by inducing the surface expression of E-receptors what leads to rosette formation and, thus, contributes to lymphocyte differentiation. The increase in the amount of active T-cells which represent the mature cell population also confirms the participation of RNase Bi in T-rank lymphocytes differentiation processes. The RNase Bi effect on the human lymphocytes depends on its catalytic activity.

Adhesion of peripheral blood mononuclear cells to vascular endothelium in patients with systemic sclerosis (scleroderma)

OBJECTIVE

Perivascular infiltrates in skin, subcutaneous tissue, and internal organs are a characteristic feature of early systemic sclerosis (SSc). We studied the first step of migration of peripheral blood mononuclear cells (PBMC) through the vessel wall to the extravascular space, i.e., adhesion of PBMC to endothelial cells (EC), in patients with various forms of SSc (limited scleroderma, diffuse scleroderma, and the transitional form).

METHODS

Radioisotope-labeled patient PBMC were coincubated with umbilical cord EC in vitro, and the percentage adhesion was measured.

RESULTS

Adhesion of PBMC to EC was markedly decreased, while adhesion of isolated active rosette-forming cells (ARFC) was significantly increased, in SSc patients compared with healthy controls. Decreased adhesion of PBMC to EC was found to correlate with a diminished percentage of ARFC in the peripheral blood. Preincubation of PBMC from healthy donors with interleukin-2 (IL-2) enhanced their adhesion to EC, while preincubation of PBMC from SSc patients with this cytokine resulted in a decrease in adhesion in 10 of 14 individuals. IL-1, interferon-gamma, and transforming growth factor beta had no significant effect on adhesion of SSc patient PBMC to EC. Differences in adhesion of PBMC to EC among the SSc subgroups were not significant.

CONCLUSION

Our findings suggest that in SSc, activation of subpopulations of PBMC leads to their enhanced adhesion to vascular endothelium in vivo and to migration of these cells to the extravascular space, resulting in the elimination from the peripheral blood of those PBMC with high ability to adhere to EC.

E-rosettes in aging: meta-analysis of the literature

In this meta-analysis of the literature, it is affirmed that aging is associated with a small but significant decline in peripheral E-rosette-forming cells while high affinity E-rosettes (active or early rosettes) increase. The author speculates that this differential age effect may reflect the abnormal capping behaviour of E-rosettes or a change in the cell surface charge properties. A type II error is a common trait of the reviewed studies and could well explain the great number of reports concluding that E-rosette-forming cells are unaltered in the elderly.

Theophylline-resistant and theophylline-sensitive "active" and "total" E rosette-forming lymphocytes in patients with systemic scleroderma

Using the E rosette test and its modification with theophylline, we have studied T regulatory lymphocytes in various forms of systemic scleroderma. Mean percentages of active rosette-forming cells (ARFC) as well as the fraction resistant to theophylline incubation (ARFC-res) were significantly decreased, irrespective of the variety of the disease, compared to the age-matched controls. Late ("cold") rosette-forming fractions were unimpaired. The theophylline-sensitive fraction of total rosette-forming cells (TRFC-sens), which contains mainly cells from the suppressor circuit, was found to be lowered in all patients groups studied, whereas the ARFC-sens fraction was significantly decreased only in patients with diffuse scleroderma over 50 years of age, in whom there was a tendency to a more severe course, as manifested by pronounced systemic organ involvement. The lowered values of E rosette tests were found in a majority of SSc patients and were correlated with the appearance in the sera of factors capable of inhibiting ARFC formation by normal human peripheral blood T lymphocytes. Normal values of the E rosette test were related to the presence in the patients' sera of factors stimulating ARFC formation by normal lymphocytes. We surmise from the results that in SSc patients the T-cell defect is not only restricted to T suppressor cells but also refers to the active theophylline-resistant fraction containing mainly T inducer and T cytotoxic cells.

Partial defects of cell-mediated immunity in patients with epidermodysplasia verruciformis

Different parameters of cell-mediated immunity, including natural cytotoxic reactions, were studied in nine patients with epidermodysplasia verruciformis with or without cutaneous malignancy. We found decreased total number of T lymphocytes and T-helper cells in peripheral blood of the patients, and normal T-suppressor cell number, as detected by monoclonal antibody typing and functional E-rosette test with the use of theophylline. This decrease was found both in active and in late rosette-forming cell subpopulations. Natural killer cell activity of peripheral blood mononuclear cells was found to be increased in four of nine patients with epidermodysplasia verruciformis, whereas antibody-dependent cellular cytotoxicity was within the normal range in all patients studied. Lymphocyte-induced angiogenesis assay, which is a sensitive test for the estimation of the immunocompetence of lymphoid cells, revealed increased angiogenic capability of peripheral blood mononuclear cells in the majority of the patients. Our results suggest that cellular defects in patients with epidermodysplasia verruciformis did not relate to all functions of the immune system.

Rosette formation between T and autologous B lymphocytes. I. Characterization of a T cell subpopulation

The ability of some T cells to form rosettes with autologous B lymphocytes (TrB cells) appears to be a marker of a subpopulation of T cells, a majority of which have high avidity receptors for sheep red blood cells. TrB cells have a higher proportion of suppressor cell surface markers (OKT-8+ and receptor for the Fc fraction of IgG), as well as higher suppressor activity than other T cell populations. TrB cells also help in B lymphocyte transformation under the stimulation of a T-dependent B mitogen. The TrB cells seem to express the Fc gamma receptor after ecotatic association with B cells, since T gamma cells previously isolated from total T cells form rosettes with B cells in the same proportion in which total T cells do. Studies on TrB cells subpopulation may explain some of the defects in functional cell-cell interactions.

Immunological profiles in alopecia areata

Cell-mediated immunity and auto-immune phenomena were investigated in sixty patients with active alopecia areata of various degrees of severity. Serum auto-antibodies to thyroid antigens were detected in twenty-three patients. Examination of T-lymphocyte populations, lymphocyte DNA synthesis, and lymphokine production in response to mitogen stimulation revealed no differences between the sixty patients and matched healthy control subjects. However, patients with thyroid auto-immunity and/or the presence of alopecia totalis or universalis showed significant reductions in interactive T lymphocytes (recognized by rosette formation with human B lymphoblastoid cells) and diminished production of leukocyte migration inhibition factor in response to stimulation with phytohaemagglutinin. This suggests that immune mechanisms may be involved in the pathogenesis of alopecia areata which is associated with thyroid auto-immunity or which progresses to total hair loss.

T antigen expression by human lymphocytes in relation to E rosette affinity

Active and late rosette-forming cells, separated on the basis of their different affinities for SRBC, were tested for their ability to react with monoclonal antibodies of the OKT series. No significant preferential distribution of T subpopulations defined by these reagents was found in the high affinity E rosette fraction, while in the low affinity T cell subset the major finding was a high number of cells lacking both OKT4 and OKT8 determinants. This seems to be related to methodology, as indicated by experiments in which sequential cycles of rosetting procedures were found to induce loss of reactivity with OKT monoclonal antibodies. The implications of these methodological observations are further discussed.

Active T rosettes, human autologous T rosettes, OKT8 and OKT4 cells, con A-induced suppressive activity, and autoantibodies: clinical correlations

Correlations between various T-cell subsets: OKT4, OKT8, TEh (human autologous T rosettes), and TEa (active T rosettes) cells and the concanavalin A-induced suppressor function assessed on Con A proliferation have been analyzed in 46 patients with various secondary immunological disorders. The different T subsets and the suppressive activity were also compared in patients with and without autoantibodies. Significant positive correlations were found between T-cell markers TEa-OKT8 and TEh-OKT4. Significant inverse correlations were also found between Con A-induced suppressive activity-OKT4/OKT8 ratios, and TEa-OKT4/OKT8 ratios suggesting that the subpopulations identified by the active T rosettes are probably involved in T immunoregulatory mechanisms. There was no association between the Con A-induced suppressive function or the T markers TEa, OKT4, and OKT8, and the presence of autoantibodies. Only subjects with autoantibodies had a lower percentage of T lymphocytes forming autologous rosettes. These observations emphasize the fact that lack of correlation may exist between markers or function and immune status in some patients.

Enkephalins--enhancement of active T-cell rosettes from lymphoma patients

Methionine enkephalin was found to increase significantly the active T-cell rosettes from lymphoma patients. In sharp contrast, the leucine enkephalin was observed to increase active rosettes only at a single low concentration. Neither enkephalin significantly altered the total T-cell rosettes. It is suggested that methionine enkephalin could have a significant influence in enhancing cell-mediated immunity and T-cell function, particularly in lymphoma patients.

Low-affinity E-rosette-blocking factor in hemodialysis-treated patients in chronic renal failure

Enumeration of total E-rosette-forming cells (t-ERFC) enabled 30 renal failure patients on hemodialysis to be classified into three groups: group 1 with normal numbers of t-ERFC, and groups 2A and 2B with reversibly and irreversibly reduced numbers, respectively. Duration of dialysis treatment was the only distinguishing feature between these three groups, being shorter for group 1 than for group 2A (P less than 0.02) and shorter for group 2A than for group 2B (P less than 0.001). However, a rosette-blocking factor (RBF) was demonstrated in all three groups which predominantly affected the low-affinity ERFC (i.e., total ERFC minus active ERFC). This factor could be partially absorbed (P less than 0.01) on normal lymphocytes and showed increased activity after a single dialysis session, suggesting the removal by dialysis of a putative anti-RBF substance.

Cell-mediated immunity in normal pregnancy and pre-eclampsia

The in vitro responses of maternal lymphocytes to phytohaemagglutinin (PHA), concanavalin A (Con A) and purified protein derivative of tuberculin (PPD) were determined in uncomplicated and pre-eclamptic pregnancies and nongravid female controls. PHA, Con A and PPD responses were significantly lower in both pregnant groups compared to nongravid controls. No difference was observed in lymphocyte reactivity between women with pre-eclampsia or uncomplicated pregnancy. Both pregnant groups exhibited normal numbers of circulating T and B lymphocytes. The number of active E rosette-forming cells was significantly higher in peripheral blood of pre-eclamptic patients.

Identification of "active" T lymphocytes among effector cells in guinea pigs

Guinea pig T lymphocytes have receptors of different affinity for rabbit red blood cells (RRBC): those binding RRBC immediately are termed "active" T cells; the remainder, which bind RRBC only after longer incubation times, are "non-active" or "late-rosetting" T cells. We have found that these two subpopulations have different functional characteristics. Active T cells could not be stimulated effectively with phytohemagglutinin (PHA), and stimulation with concanavalin A (ConA) increased their DNA synthesis only at high concentrations. The non-active subpopulation responded better to PHA but poorly to ConA. Unseparated (total) T cells, however, responded well to both mitogens, suggesting a helper effect by the active T cells. The presence of monocytes in T-cell cultures further enhanced mitogen-induced DNA synthesis. Active T cells were not present in guinea pig bone marrow, whereas they constituted 10% of all lymphocytes in the thymus, 13% in the spleen, 29% in lymph nodes, and 32% in the peripheral blood. After administration of antigen in vivo, the number of active T cells in the regional lymph node increased, whereas the number of total T cells did not change. The similarity of the active T cell populations in guinea pigs and humans increases the usefulness of these animals for preclinical tests of potential new immunomodulating agents.

Lymphokine production in T-lymphocyte subsets defined by active E-rosette formation

Human T-cell subsets, defined by active E rosette formation, were examined for their ability to produce leucocyte migration inhibitory factor (LIF) in response to mitogen or specific antigen. It was determined that T cells enriched for active rosette-forming (A+) cells produced LIF in response to concanavalin A, whereas T cells depleted of active rosette-forming (A-) cells did not. Similarly, A+ cells from a tuberculin-sensitive donor produced LIF in response to tuberculin purified protein derivative, whereas A- cells from the same donor failed to produce the mediator. Thus, T-cell production of LIF in humans appears to be restricted to those T cells capable of active rosette formation.

Fetal cytotoxic antibodies to maternal T-lymphocytes: a possible mechanisms for maternal tolerance of the fetal allograft

The absolute numbers of B lymphocytes and of total and "active" T lymphocytes in peripheral venous blood (Mv) from 15 females at the time of normal term deliveries were found to be significantly less (p less than 0.001) than in the fetal umbilical vein (Uv) or artery (Ua) or in the peripheral blood of 75 normal nonpregnant controls (Cv), suggesting that maternal cellular immunity at term is lowered. In 19 umbilical artery samples, titers of lymphocytotoxic antibodies (Cyt), expressed as the mean log of reciprocal titer values, were significantly higher (p less than 0.01 in each case)( than in matched maternal samples, against the following cell types: Maternal T cells (7.1 in Ua vs 1.21 in Mv sera); maternal B cells (3.23 vs 1.58); T cells (4.41 vs 1.38) but not B cells from other females at delivery; autologous T cells (2.9 vs 1.0); autologous B cells (1.88 vs 0.69); T (5.39 vs 0.81) and B (2.80 vs 1.25) cells from the paired Uv; T (3.78 vs 0.62) and B (2.64 vs 0.77) cells from the Uv of other newborn infants; and T (4.19 vs 2.0) but not B cells from controls (Cv). The highest Cyt titers in the umbilical artery samples were against maternal T lymphocytes. Immunofluorescence studies indicated that the Cyt antibodies were primarily IgG. Absorption of 13 other Ua sera with maternal T cells eliminated with Cyt activity against both Mv and Cv T cells; absorption with Cv T cells eliminated the reaction against Cv T while reducing cyt titres to Mv T lymphocytes. We conclude that the fetus produces lymphocytotoxic antibody specifically directed against maternal T lymphocytes, in addition to antibody against T lymphocytes of other adults.