Recent evidence has indicated that there is heterogeneity among interferons produced by different cells responding to a variety of stimuli. Thus far very little has been done to characterize these interferons and to examine their functional interrelationships. Therefore we plan to examine the synthesis of interferon by subsets of human T lymphocytes prepared by immunologic fractionation (T gamma-T micron-T phi) and by density gradient fractionation in response to mitogens (PHA, PWM, Con A), C. parvum, bacterial antigens (PPD) and viral antigens (vaccinia). Also we will characterize the physical properties and host range specificity of immune interferons and determine if these properties are influenced by the nature of the inducer, by the cell of origin, or by the accessory cells in culture, and we will compare immune and classical interferons. Furthermore, since interferon is itself produced by cells of the immune system its synthesis reflects the status of that system and can now be used as a means to dissect out abnormalities of lymphocyte, monocyte, and macrophage function in various disease states. We will therefore study in patients with immunodeficiency diseases (selective IgA deficiency, ataxia telangiectasia and thymic hypoplasia) and thymic hypoplasia) and autoimmune diseases (lupus erythematosus) the production of immune interferon by mitogen or C. parvum stimulated lymphocytes as a measure of the effector competence of T lymphocyte subsets and as a measure of the integrity of macrophage function.