Active and late rosette-forming cells: immunological and cytochemical characterization

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.

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.

Theophylline-resistant and theophylline-sensitive "early" and "late" E rosette-forming cells in young and aged humans

The percentage of cells with high-affinity sheep red blood cell (SRBC) receptors, "active" or "early" rosette-forming cells, (ARFC) in theophylline-resistant peripheral blood T lymphocytes achieve higher values in aged subjects and, in particular, in the group with clinically manifested atherosclerosis. A diminished OKT-4/OKT-8 ratio in theophylline-resistant ARFC was noticed in this group. On the contrary, the proportion of the theophylline-resistant cells with low-affinity receptors, cold or late rosette-forming cells (CRFC) attained lower values in aged subjects than in young subjects. No statistical difference in the proportion of theophylline-sensitive T cells was evident between old and young people, both in ARFC and CRFC fractions. This is indicative of the elevation of activated (or less differentiated) cytotoxic T cells in the peripheral blood of aged subjects with clinically manifested atherosclerosis. The clinical aspect is still to be considered.

Beta-glucuronidase activity in human T and B lymphocytes and the Tmu and T gamma subpopulations

The beta-glucuronidase staining characteristics of isolated T cell populations and the Tmu and T gamma enriched fractions derived of them were studied. T gamma lymphocytes were obtained from purified T lymphocytes by ox-IgG rosette sedimentation. The rosette-forming cells in the pellet were referred to as T gamma lymphocytes, whereas the lymphocytes in the interface were referred to as T gamma depleted or Tmu lymphocytes. B cells were studied on rosetted mononuclear cells with either mouse erythrocytes or with Staphylococcus Aureus (Cowan I) bacteria, after a preceeding polyvalent anti-human Ig treatment of the cells. While B cells showed mostly no reactivity, Tmu and T gamma cells were respectively characterised by a "dot-like" and "granular" pattern of reactivity. These findings are in agreement with those observed by others after alpha-naphthyl-acetate esterase or acid phosphatase staining. Within the T lymphocyte fraction, the T non-mu, non-gamma lymphocytes seemed to have a granular pattern of reactivity. The same staining pattern was found in non-B, non-T lymphocytes.

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.

The in vitro effect of phenytoin and carbamazepine on subpopulations of human blood mononuclear cells

Mononuclear cells from peripheral blood of 10 healthy blood donors were incubated with phenytoin and carbamazepine dissolved in 1% propyleneglycol. Phenytoin 20 mg/1 significantly reduced the percentage of active E rosette-forming T-lymphocytes; to mean 17.6% compared to mean 25.9% in control incubations (P less than 0.05). Carbamazepine 10 mg/1 reduced this percentage to 21.0% (0.05 less than P less than 0.10). Phenytoin reduced the percentage of active T-lymphocytes in 9 of the 10 cell suspensions, while carbamazepine reduced the active T-lymphocytes in 8 of the 10 suspensions. The percentage of total E rosette-forming T-lymphocytes was similarly reduced by 20 mg/1 phenytoin and 10 mg/1 carbamazepine; from 65.3 to 59.5% and to 60.3%, respectively (P less than 0.05, 0.05 less than P less than 0.10). The reduction of active and total T-lymphocytes was concentration-dependent for both drugs. Phenytoin and carbamazepine 5 mg/1 did not influence the percentage of T-lymphocytes. The decrease became apparent at a concentration of 10 mg/1 for both drugs, and grew steadily more marked with increasing drug concentrations up to 80 mg/1. However, the reduction in the percentage of T-lymphocytes was more pronounced for phenytoin than for carbamazepine at all drug concentrations. The percentage of cells with Fc gamma-receptors and of those with receptors for the activated human complement component C3b, were not influenced by phenytoin and carbamazepine, nor were the cells with phagocytizing capacity and the non-phagocytizing cells with membrane-bound immunoglobulin (i.e. B-lymphocytes).

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.