Involvement of the spleen in murine B cell differentiation.

Experiments were performed to study the influence of neonatal and adult splenectomy on B cell differentiation in mice. Lymph node cells of both groups were found to contain a significantly higher proportion of Ig-bearing cells. Moreover, these cells expressed a higher density of membrane Ig and a higher IgM/IgD ratio. In addition, the response of these cells to different polyclonal B cell activators, especially dextran sulfate, was much higher than the response of the sham-operated controls. Similar experiments were carried out in splenectomized and control animals that were lethally irradiated and reconstituted with different hemopoietic cell sources. The same pattern of results was obtained, except when reconstituting the irradiated animals with fetal liver cells. These experiments, which were performed at long time intervals post splenectomy, show that in the absence of the spleen, there is an accumulation of less mature B cells in the periphery implying an active role of the spleen in at least certain differentiation steps of the B cell lineage.