Ability of spleen, peritoneal cavity, and lymph node B cells to reconstitute serum immunoglobulin in SCID mice.

The impact of intrinsic B lymphocyte heterogeneity and of microenvironmental influences on serum immunoglobulin production by B cells was examined by intravenous (i.v.) and intraperitoneal (i.p.) transfer of BALB/c and BALB.xid (X-chromosome-linked immunedefective; XID) lymph node (LN), splenic (SP) and peritoneal cavity (PerC) cells into severe-combined immune-defective (SCID) mice. The results indicate that each B-cell source restores all immunoglobulin classes within 5 weeks of transfer, the rates for each isotype, however, differ between the B-cell sources. Serum IgM levels were restored most rapidly by PerC cell transfer, followed by SP and LN cell transfer. In addition, normal immunoglobulin levels were reached in the absence of complete lymphoid reconstitution. Serum immunoglobulin phenotypes characteristic of the donor strain, e.g. reduced IgM and IgG3 production by XID B cells, were maintained after transfer into the SCID recipient. Microenvironmental influences were indicated by reduced immunoglobulin production after i.p. transfer and after i.v. transfer into irradiated SCID recipients. The data show that both B-cell type and microenvironment play significant roles in generating the heterogeneous pool of B cells required for humoral immunity.