Organ distribution and intracellular localization of viral antigens in C58 mouse leukemias were investigated in detail by the immunofluorescent complement fixation method. During successive transmission of C58 mouse lymphocytic leukemia by cell-free filtrates myelocytic leukemia developed. Whether this myelocytic leukemia was caused by the same or different virus was investigated by the above immunofluorescent procedure.
1. More distinct and increased particle fluorescence which indicated the presence of leukemia viral antigens were detected by the immunofluorescent complement fixation method than by the direct method.
2. The viral antigens in the leukemic cells were localized in 4 different types; perinuclear arrangement, intracytoplasmic scattering, arrangement near the cytoplasmic membrane and extracellular localization. There was no observable difference in localization of viral antigens between the lymphocytic and myelocytic leukemias.
3. Of organ distribution, more viral antigens were observed in the bone marrow and lymph nodes and a few in the spleen and liver in the lymphocytic leukemia. Less viral antigens were observed in the bone marrow and lymph nodes in the myelocytic leukemia.
There were no viral antigens in the organs of the non-leukemic C58 mouse. Cross-immune reactions using antiviral antisera of the lymphocytic and myelocytic leukemias showed that the two viruses closely resembled but were not identical. These findings were indicative of the presence of the two types of viruses in the C58 mouse leukemias.