Investigation of cellular immune response in patients with viral diseases, working on the hypothesis that viral infection of B lymphocytes causes an alteration of surface of these cells, thus enabling them to stimulate the patients' T cells. Continued perfection of the technique of cryopreservation of lymphocytes and further study, via this technique, of (1) the preservation of normal lymphocyte surface T and B cell markers by conventional freezing and thawing and (2) preservation of reactivity to mitogens and antigens. Investigation of local events underlying host virus interaction in the liver of patients with viral hepatitis. Use of needle biopsy specimens, simple homogenation, and ficoll-hypaque separation to obtain liver lymphocytes from patients with hepatitis. Further identification of T cells in involved livers by method of these cells rosetting with sheep red blood cells. Evaluation of the reactivity of peripheral and liver lymphocytes to viral antigens via defined and purified hepatitis antigens. Isolation of hepatocytes, through modification of ficoll-hypaque fractionation, for detection of viral antigen and in vitro cytotoxity of local and peripheral lymphocytes towards infected cells.