In Vitro studies on human B and T cell purified populations. Stimulation by mitogens and allogeneic cells, and quantitative binding of phytomitogens.

The property of T cells to form rosettes with sheep red blood cells has been used to separate peripheral blood lymphocytes into purified T- and B-cell suspensions after density gradient centrifugation. A study of lymphocyte markers has shown that 2-6 per cent of E rosettes only were recovered in the B cell-enriched population. Lymphocyte stimulation in vitro was obtained with PHA, con A and PWM in unseparated and T-cell populations, but never in B-cell suspensions. Experiments of recombination between the two purified fractions have demonstrated that 10% of T cells added to B cells were able to induce a response to PHA and PWM. Otherwise, only T cells responded to allogenic stimulation. Lastly, B and T cells seemed to bind qualitatively and quantitatively the same mitogens on their membranes.