Sequential Changes of T-and B-Cells, Virus Antigen Expression and Primary Histologic Tumor Diagnosis in Virus-Induced Lymphomagenesis of Mice*

T- and B-cell counts, estimation of Ig receptor fluidity, and expression of virus-coded antigens were correlated with histological findings during the development of virus-induced mouse lymphoma. Tested were BALB/c mice after infection with the strongly oncogenic Moloney leukemia virus (MLV), the moderately oncogenic (in BALB/c mice) Gross passage A virus (GLV-A), and the essentially non-oncogenic Gross 3T3 tissue culture virus (GLV-T). Methods included immunofluorescence microscopy with antisera against T-cells, B-cells and MLV intact virus, routine histology, and electron microscopy. Following time sequence of changes was observed in mice with oncogenic MLV- and GLV-A infection but not in GLV-T infection: Significant decrease of Ig receptor fluidity and expression of virus antigen were observed already at the initial investigation,i.e. 2 weeks post virus infection. This was followed by significant decreases in percent T-cells 5–8 weeks later, accompanied by histologic atrophy of the thymus and of thymus-dependent regions of lymphatic tissues. Another 2–8 weeks after the decrease in percent T-cells occurred, the first lymphomatous foci became obvious in the thymus. Clinically overt and generalized lymphoma was diagnosed at 20–30 weeks post virus infection.