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The cytolytic effect of Streptolysin O to leucocytes, T and B lymphocytes and granulocytes has been examined using an in vitro immuno lymphocytolytic test at 62 patients with different dermatological diseases. This test was established to be only about the immuno-cytolytic reaction of the T lymphocytes, and this process was bound to the present of complement. It is suggested that this method is suitable to in vitro study of the cellular immunity of patients with chronic infectious diseases.

An exopolysaccharide (EP), purified from spent culture fluid previously inoculated with Capnocytophaga ochracea strain 25, suppressed in vitro human peripheral blood lymphocyte responses to the mitogen concanavalin A. EP was suppressive when added to cultures before the mitogen, but enhanced responses when added 24 or 48 hr after the mitogen.

Human peripheral blood mononuclear lymphocytes from individuals with moderate periodontitis were separated into purified subpopulations of T lymphocytes and B lymphocytes by rosetting with sheep red blood cells (E). All three lymphocyte subpopulations were compared for proliferative responses to cell walls from seven oral bacteria, phytohemagglutinin (PHA), pokeweed mitogen (PWM), lipopolysaccharide (LPS), and streptolysin-O (SLO). Mononuclear cells and a re-combined subpopulation consisting of four parts purified T lymphocytes and one part B lymphocytes responded significantly to all of the stimulants. Purified T lymphocytes by themselves responded significantly to PHA and PWM, but were unresponsive to oral bacteria and SLO; however, T lymphocytes cultured with 2% autologous macrophages responded significantly to all seven oral bacterial cell walls and to SLO, which indicates that T-cell responses to oral bacteria are macrophage-dependent. T-cell-depleted non-E-rosette-forming B cells by themselves were poorly responsive to all of the tested stimulants; however, the responses of these cells to oral bacteria, PWM, LPS, and SLO increased significantly in the presence of 10% mitomycin-C-treated T cells, demonstrating that B cell proliferation to these stimulants is T-cell-dependent.

The response of lymphocytes from patients with syphilis and normal subjects was studied in vitro by using phytohemagglutinin (PHA), pokeweed mitogen (PWM), streptolysin O (SLO), and a preparation of Treponema refringens. Normal lymphocytes exhibited a dose-response curve to treponemes. Although lymphocytes from patients with primary and secondary syphilis responded normally to PHA and PWM, their response to SLO was suppressed and they failed to show significant stimulation by treponemes. Serum from syphilitic patients did not affect normal lymphocytes, and culturing lymphocytes from patients with syphilis in normal serum did not restore their responsiveness. Six to 10 weeks after syphilitic patients had been treated, the degree of stimulation by treponemes was the same as for normal subjects. These data give indirect support to the hypothesis that immunological suppression occurs during active infection with T. pallidum.

When lymphocytes are stimulated to enlarge and divide by treatment with phytohemagglutinin, most of the rapidly synthesized RNA is nonribosomal. The phenomenon is a response by lymphocytes to stimulation by phytohemagglutinin, rather than a general concomitant of lymphocyte growth.

Continuous exposure to 0.1 international unit or more of Escherichia coli L-glutaminase inhibited responses of human lymphocytes to phytohemagglutinin, streptolysin O, and allogeneic leukocytes. Inhibition was completety reversed by removing the enzyme from the culture or adding L-glutamine but not L-asparagine. Cytoxicity did not occur. L-Glutaminase should be immunosuppressive in vivo.