Thrombocytopenia, a Prelymphoid Leukaemic Sign in AKR Mice

Abstract

ELECTRON microscopy has revealed that the “C”-type viral particles of the murine and feline leukaemias are characteristically present in the cytoplasm of megakaryocytes and platelets^1–4. In mice thrombocytopenia can be used in dose response curves to titre both Friend and Rauscher viruses^5,6. The thrombocytopenia that occurs after Rauscher virus infection is biphasic. The initial dose dependent thrombocytopenia develops within 48 h of infection and reaches its nadir 2 weeks later. At this time the bone marrow is hypercellular with megakaryocytic hyperplasia and there is no infiltration by leukaemic cells. Within 4–6 weeks in the surviving mice spontaneous recovery occurs, but 10–24 weeks after infection thrombocytopenia again develops, then associated with lymphocytosis in the peripheral blood, leukaemic cell infiltration of the bone marrow, and reduced numbers of megakaryocytes⁷.