Functional and histological studies of adoptive immunity in neonatally transplanted rabbits.

The adoptive transfer of immunity by means of spleen and lymph node cells has been analysed in rabbits of defined major histocompatibility (RLA) types and immunoglobulin (Ig) allotypes. Previous results had shown that chimaeras formed by transplanting adult cells into RLA-matched newborn hosts become stable B-lymphocyte chimaeras, as determined by their continuous production of donor type Ig. However, specific antibodies made by adult chimaeras were demonstrably only of recipient origin, unless the donor had been primed. The present report describes early events after the transfer of cells from donors primed with trinitrophenylated keyhole limpet haemocyanin (TNP-KLH). Double-staining with enzyme-labelled antigen or antibody conjugates was applied to identify lymphocytes of donor or recipient origin in spleen sections of transplanted rabbits and also to identify cells producing anti-TNP. Lymphocytes with membrane-bound Ig (mIg+ cells) of donor allotype were readily identified scattered singly or in small clusters throughout the recipients' B-lymphocyte areas within 5 days after transfer. Groups of donor-derived cells producing anti-TNP were demonstrable only in animals that had been specifically stimulated. Serological analysis and lymphocyte marker and function studies correlated well with results obtained by the histocytochemical approach. These results show that a systematic study of the role and importance of mature B lymphocytes in transplantation is now feasible.