Plasma inhibitors of lymphocyte response to phytohaemagglutinin in children with recurrent infections.

A survey of the immunological status of 175 children with recurrent infections showed that the plasmas of fifteen patients contained an inhibitor of lymphocyte response to phytohaemagglutinin (PHA). The inhibitors could be subdivided into two groups. One type of inhibitor acted only on the patients' lymphocytes (autologous-only). The other type also inhibited the response of control lymphocytes to PHA and in the mixed lymphocyte reaction (homologous). Plasma inhibitors of both types inhibit the response of rabbit lymphocytes to PHA. Patients with a plasma inhibitor frequently have a raised resting lymphocyte DNA synthesis.