Studies on the Effect of Splenectomy on the Total Leukocyte Count in the Albino Rat

1. Following splenectomy in the albino rat, the total leukocyte count increased approximately 100 per cent in seven days, and remained significantly elevated for seventy to ninety days, after which time time leukocytes returned to normal levels. This increase in circulating leukocytes was due to an increase in both neutrophils and mononuclear cells. Partial omentectomy and unilateral nephrectomy produced increases of less magnitude and much shorter duration than those which followed splenectomy.

2. Removal of as much as 75 per cent of the spleen resulted in a leukocyte increase resembling in magnitude and duration that of control operations.

3. When small portions (less than 10 per cent) of the spleen were transplanted to other sites, the leukocyte response also resembled that which followed the control operations.

4. When splenectomy was performed in one partner of parabiotic rats, no rise occurred in the leukocyte count of either animal. When the spleen of the second partner was then removed, a rise in the leukocyte count of both animals occurred.

5. When rats were made leukopenic by pteroylglutamic acid deficiency, no rise in the leukocytes in the peripheral blood occurred following splenectomy.

6. It is concluded that in the rat the spleen exerts an influence on the level of circulating leukocytes, and that the results of these experiments support but do not conclusively prove the hypothesis that this organ exerts this influence by controlling the rate of production and/or liberation of leukocytes in the bone marrow. These studies do not exclude the possibility that under certain circumstances the spleen may destroy white cells.