The Recovery of the B-cell Population in Adult Thymectomized, Lethally Irradiated and Bone Marrow-Reconstituted Mice.

The recovery of the B-cell population in adult thymectomized, BM mice) was studied. The irradiated and bone marrow-reconstituted mice T x number orb cells in the spleen of T × BM mice was estimated at various times after bone marrow transplantation. The spleen cells to be tested were mixed with dexamethasone-resistant thymocytes (DRT) and sheep red blood cells (SRBC) and transferred to irradiated recipients. The number of plaque-forming cells (PFC) in the spleen of the recipients was determined 7 days later. Using this functional B-cell assay a sequential appearance of the precursors of IgM-, IgGand IgA-PFC in the spleen of T × BM mice was observed. The precursors of IgM-PFC (IgM-B cells) were present immediately after transplantation. The first IgG-B cells could be detected at 13-16 days after transplantation and the IgAB cells finally appeared at 22 days after transplantation. The number of B cells reached a constant and normal level at 30 days after transplantation. The IgM-. IgG- and IgA-B cell development in sham-thymectomized, irradiated and bone marrow-reconstituted mice (ST × BM mice) was virtually the same as in T × BM mice. [ABSTRACT FROM AUTHOR]