Changes in Spleen Cellularity and Erythrocyte Accumulation Following Rauscher Virus Infection in the Mouse

The nature of the relationship of the spleen enlargement effected by Rauscher virus infection of SJL/J mice has been investigated with reference to cell proliferation in the spleen and to splenic red blood cell pooling and anaemia. The gross splenic nucleated cell content was found to increase linearly with spleen weight. The ratio of total spleen cells to nucleated spleen cells was identical at a value of 1.75 to 1 for both normal and virus infected mice even though in the latter some spleen sizes were as high as 30 times normal. On a per milligram basis, the average splenic accumulation of ⁵⁹Fe labelled normal red blood cells by normal mice was approximately twice as great as by 18 day leukaemic mice, even though the leukaemic spleens contained a greater fraction of the injected label. Anaemia was seen to develop shortly after injection of the virus, reducing the haematocrit to values of less than 40 by two weeks. Compensatory increase in reticulocyte number did not occur until after the major fall in venous haematocrit had already been achieved. Peripheral white blood cell counts increased with time after virus injection and these correlated positively with spleen size, the relation being logarithmic. The data confirm the assumption that splenomegaly is a direct result of the cellular proliferative effects of Rauscher virus rather than a consequence of increased red blood cell pooling in the spleen.