Lymphocyte chimerism after bone marrow transplantation. Surface markers and in vitro function of donor and recipient lymphocyte subpopulations.

Specific HLA antibodies were used to eliminate donor and recipient cells, respectively, from lymphocyte suspensions prepared from the blood of a child who had been transplanted with bone marrow from an HLA-A- and HLA-B-incompatible, HLA-D-compatible donor. About 70% of the lymphocytes were of donor HLA type, the remaining of recipient type. The phytohemagglutinin-responsive lymphocytes were exclusively limited to the lymphocyte population carrying donor-type HLA antigens. Membrane immunofluorescence investigations of the donor and recipient populations showed a low percentage of IgM-positive lymphocytes in the donor population and an extremely high proportion of IgM-positive lymphocytes in the recipient population. About 90% of the donor lymphocytes were T cells, as judged by their capacity to form rosettes between sheep erythrocytes and T lymphocytes; no cells in the recipient cell population expressed this ability.