Spontaneous production of human gamma interferon in vitro by splenic lymphocytes of patients with idiopathic thrombocytopenic purpura.

Lymphocytes derived from spleens of traffic trauma victims do not appear to produce human interferon (IFN) activity, spontaneously, in vitro. However, lymphocytes derived from spleens of four ITP patients were found to produce significant amounts of human IFN activity. The IFN activity produced by the splenic lymphocytes of ITP patients was neutralized by anti-gamma-IFN antisera but not anti-alpha or anti-beta antisera. The IFN activity was found to be unstable at pH 2.0 and at 56 degrees C. Thus the human IFN activity of splenic lymphocytes is characterized as human gamma-IFN. No human IFN activity was detectable in the serum of the ITP patients and it is not known whether the splenic lymphocytes of ITP patients also produce human gamma-IFN in vivo. The observations suggest that conditions prevail in the ITP state that predispose the splenic lymphocytes to produce human gamma-IFN without stimulation by exogenously added inducer.