Antibody formation in mouse bone marrow: IV. The influence of splenectomy on the bone marrow plaque-forming cell response to sheep red blood cells

Abstract

Mouse bone marrow is barely capable of plaque-forming cell (PFC) activity during the primary response to sheep red blood cells (SRBC). However, during the secondary response, it becomes the major center of activity containing IgM-, IgG-, and IgAPFC. In the present paper the influence of splenectomy was studied on primary and secondary PFC activity in the bone marrow. Differences in primary and secondary bone marrow PFC responses are probably related to the presence of B and T memory cells in situ. Therefore the effect of splenectomy on the appearance of B and T memory cells in the bone marrow was also investigated. Splenectomy before intravenous (iv) immunization with 4 × 10 8 SRBC prevented any primary PFC activity in the bone marrow. The influence of splenectomy before priming on secondary PFC activity in the bone marrow depended on the priming dose of SRBC. Splenectomy before priming with 10 7 SRBC iv completely prevented IgM-, IgG-, and IgA-PFC activity in the bone marrow upon subsequent boosting with 4 × 10 8 SRBC iv. By means of cell transfer experiments it was shown that after splenectomy no B or T memory cells appeared in the bone marrow after priming with 10 7 SRBC iv. The effect of splenectomy on both secondary PFC activity and appearance of B and T memory cells in the bone marrow could be partly overcome by iv priming with a higher antigen dose of 4 × 10 8 SRBC. Cell transfer experiments showed that splenectomy before priming with 10 7 SRBC iv not only interfered with the appearance of B and T memory cells in the bone marrow, but also with the appearance of B memory cells in peripheral lymph nodes, mesenteric lymph node, Peyer's patches, thymus, and blood. This indicates that after immunization with 10 7 SRBC iv all B and T memory cells which appear at extra splenic sites, are generated in the spleen. Immunization of splenectomized mice with 4 × 10 8 SRBC iv did induce the appearance of B memory cells in peripheral lymph nodes, mesenteric lymph node, Peyer's patches, thymus, and blood. We suggest that small amounts of a high dose of iv inoculated SRBC can induce the generation of B memory cells in lymph nodes and Peyer's patches.