Immunodeficiency after allogeneic bone marrow transplantation in man: the role of antigen presenting cells.

We investigated the proliferative response of donor T cells to phytohemagglutinin (PHA) presented by donor non-T cells in 7 patients after allogeneic bone marrow transplantation. Compared with the cellular response in the healthy marrow donors, T cell proliferation was found to be deficient in every recipient, from 130 to 739 days after grafting. Results of cell mixing experiments showed that the non-T cells of the patients were as capable as healthy donor non-T cells in presenting PHA to normal donor T cells. However, T cells from patients did not proliferate after substituting donor non-T cells for non-T cells from patients. This inability of T cells to proliferate was most likely the result of ineffective interactions among T cell subsets in patients after allogeneic bone marrow transplantation.