John W. Kappler

Automated fluorecent analysis for cytotoxicity assays

Classical measurements of cytotoxicity using dye exclusion and microscopic evaluation are both time-consuming and inaccurate. Using a cell sorter (TPS) a single dye system has been developed which stains live and complement killed cells with different fluorescence intensity. After exposure of target cells to antibody and complement, ethidium bromide is added to the target cells at a high enough concentration to stain complement killed cells very intensely. The cells are then diluted and lysed to produce single nuclei, permitting live cells to be stained but less intensely than the dead cells. Fluorescence intensity is measured on single nuclei at a rate of 10,000 per minute. For these studies anti-T antisera was titrated for complement dependent cytotoxic activity using normal mouse spleen cells, spleen cells from an anti-thymocyte serum treated mouse, and nylon wool purified mouse splenic T-cells. This procedure makes possible, reliable and reproducible measurement of cytotoxic activity on 5,000 cells per determination.

Functional heterogeneity among the T-derived lymphocytes of the mouse. III. Helper and suppressor T-cells activated by concanavalin A.

We have studied the properties of T-cells which when activated by concanavalin A (Con A) either suppress or help the in vitro humoral response of mouse spleen cells. Previously established criteria for the T-cell populations, T/sub 1/ and T/sub 2/ were applied. T/sub 1/ cells were defined by their short half-life (2-3 wk) after adult thymectomy (ATx) and their resistance to small doses of antithymocyte serum (ATS). T/sub 2/ cells were defined by their long half-life (approximately 15 wk) and their high sensitivity to ATS. T-cells which could be activated by Con A to help the response to the thymus-dependent antigen, sheep red blood cells, were found mainly in the T/sub 2/ subpopulation. T-cells which could be activated by Con A to suppress the response to the thymus-independent antigen, trinitrophenyl-lipopolysaccharide (TNP-LPS), were found within both the T/sub 1/ and T/sub 2/ subpopulations. These results, our previous results, and those of others suggest that the T-cell responses to phytomitogens distinguish precursors committed to different functions, while the T/sub 1/ and T/sub 2/ classifications distinguish T-cells at different stages of maturation.

Anti-Ia inhibits the activity of B cells but not a T cell-derived helper mediator

The effects of addition of anti-Ia sera to cultures of B cells responding to a number of different stimuli were studied. Anti-Ia sera inhibited the responses of B cells to thymus-dependent and thymus-independent antigens. The effects of antisera directed at different subregions within theI region were examined, using the same anti-Ia serum and mouse strains congenic atI. There was some indication that antisera directed at theI-C region might be more efficient at inhibiting responses to a thymus-independent antigen than to a thymus-dependent antigen. An antiserum to another B-cell surface component controlled by theH-2 complex, the D glycoprotein, had no effect on the response of B cells to a thymus-dependent antigen. By contrast, anti-Ia serum added to cultures had no effect on the activity of a T cell-derived, nonspecific, B-cell helper mediator (NSM). We concluded that the binding of anti-Ia sera to B-cell surfaces inhibited B-cell responses to antigen, either by competing directly with the binding of signal molecules, or by delivering an inhibitory signal to the B cell, such that it was subsequently refractory to stimulatory signals.

TWO T CELL SIGNALS ARE REQUIRED FOR THE B CELL RESPONSE TO PROTEIN-BOUND ANTIGENS1

ABSTRACT We have studied the requirements for T cell help for B cell responses to protein-bound and red blood cell-bound antigens. Anti-protein responses_need two types of helper T cells. One, apparently Ia, is needed early and delivers an antigen specific signal, and another, I-A + , is needed later and delivers a nonspecific signal.

Antigen-specific and nonspecific mediators of T-cell/B-cell cooperation. VI. Distinct patterns of cross-reactivity by two human gamma-globulin-primed helper T-cell subpopulations.

Abstract We have previously characterized the activities, in vitro, of two different helper T-cell subpopulations, primed with human γ-globulin (HGG). One T-cell subpopulation helps the response of B cells to determinants (e.g., haptens) bound to the same antigen to which the T cells are primed (specific help); the other helper T-cell subpopulation responds to the same priming antigen by secreting a nonspecific molecule which helps B-cell responses to erythrocyte antigens co-cultured with the priming antigen (nonspecific help). These subpopulations also differ in their frequency and dose response to antigen, both in vivo and in vitro. They are similarly susceptible to the induction of unresponsiveness to HGG. In order to determine whether these T-cell subpopulations share or differ in their ranges of antigen recognition, we have compared the reaction of these two HGG-primed helper T-cell subpopulations to a number of γ-globulins (γGs) from other species. Plaque-forming cells generated in response to HGG shared little or no cross-reactivity with any of the heterologous (γGs) tested. In contrast, HGG-primed nonspecific helper T cells responded with significant cross-reactivity when challenged in vitro with dog γG, but HGG-primed specific helper T cells did not respond with any such cross-reactivity. No other heterologous γG tested stimulated any significant cross-reactivity from either HGG-primed T-cell subpopulation. Thus, these two T-cell subpopulations differ in their antigenic recognition. Possible explanations of these data include: (i) a difference in receptor specificity; (ii) a difference in the receptor affinity; (iii) a difference in Ia determinants of the two subpopulations.