In vivo and in vitro activation of T-antigen receptors on leukocytes and platelets.

Serological studies on a patient whose red cells are polyagglutinable due to T activation have demonstrated concomitant T activity of the separated leukocytes and platelets. Normal leukocytes and platelets are not T active, but activation can be induced in vitro by treatment with neuraminidase or with pneumococcus type III filtrate. Such T-active cells absorb anti-T from Arachis hypogea lectin. Tests on idfferent types of separated leukocytes show that both neutrophils and lymphocytes have latent T antigen receptors. Neuraminidase treatment of platelets does not change their ability to promote clot retraction, to aggregate with ADP, or to take up serotonin.