• Immune deficiency;
  • lymphocyte transformation;
  • hereditary thrombocytopenia;
  • sex-linked

Eleven thrombocytopenic members of a large family with sex-linked hereditary thrombocyto-penia were studied. Routine immunological investigation revealed little evidence of immune deficiency, but abnormal results were obtained in studies of the in vitro blast transformation response of the patients lymphocytes. Impaired responses to microbial antigens were observed in all patients thus studied, whereas a decreased response to mitogens was observed in only one patient. Of the non-thrombocytopenic family members, approximately half showed subnormal responses to one microbial extract. These results, taken together with the increased incidence of infections in the thrombocytopenic patients, indicate the necessity for immunological scrutiny of patients with hereditary thrombocytopenia, in particular when splenectomy is considered.