This investigation uses different polyclonal activators of in vitro immunoglobulin production to elicit immunoregulatory profiles of B cells, T cells, T4 cells, and T8 cells from 25 recipients (13 with and 12 without chronic graft-v-host disease [GVHD] ) after HLA-identical marrow transplantation for aplastic anemia or hematologic malignancy. Pokeweed mitogen, Epstein-Barr virus, herpes simplex type 1 virus, and tetanus toxoid were used to induce immunoglobulin production as measured by a plaque assay. Multiple defects in the various lymphoid subsets were found in both groups of patients. There was defective b cell function, lack of T cell or T4 cell subset helper activity, and increased T cell, T4 cell, or T8 cell suppressor activity after stimulation with the various activators. Inconsistent B, T, T4, and T8 cell functions in the marrow graft recipients provide evidence for (a) different functional groups of cells within each subset responsive to different polyclonal activators; (b) a spectrum of immune capabilities within each phenotype lineage; (c) different patterns of immune reconstitution for each lymphocyte subset after marrow grafting; and (d) chronic GVHD altering recovery of in vitro functional responses to the different polyclonal activators.