Lymphocyte subsets in the blood. The influence of splenectomy, splenic autotransplantation, ageing, and the site of blood sampling on the number of B, T, CD4+, and CD8+ lymphocytes in the rat.

Removal of the largest single lymphoid organ, the spleen, leads to an increase in severe infections. To prevent this, transplantation of splenic fragments can be performed, which may, however, cause an increase in CD8+ lymphocytes in the blood of these patients. This is controversial since in the clinical situation it is often difficult to account for the different age of the patients, the time point after the operation and many other factors known to influence the number of lymphocyte subsets. Using a well-defined animal model, B, T, CD4+, and CD8+ lymphocytes were determined preoperatively in adult rats. Then, either sham splenectomy, splenectomy, or splenic autotransplantation was performed and the animals were followed up for 15 months after the operation. The surgical procedure itself, the site of blood sampling and ageing all influenced the number of lymphocyte subsets profoundly. Furthermore, giving the data as relative or absolute numbers leads to different results. Splenectomy caused lymphocytosis, due to a significant increase in B and CD8+ lymphocytes, as did splenic autotransplantation, which indicates that the number of lymphocyte subsets in the blood should not be used to argue in favour of or against splenic autotransplantation. This study demonstrates that the number of lymphocyte subsets in the blood is influenced by many factors and therefore should be determined in a highly standardized fashion.