title: Immune suppression of hematopoiesis in aplastic anemia: activity of T-gamma lymphocytes.
abstract: In vitro colony formation (CFU-c) was studied in 7 patients with severe aplastic anemia (SAA) in complete autologous hematologic reconstitution. Colony formation was depressed in all patients (less than 5% of normal). Further studies showed that 1) patients' colony formation could be enhanced by removing T cells from the marrow, but not by removing adherent cells (AC); 2) patients' marrow cells showed a marked CFU-c inhibition against normal allogeneic marrow; 3) CFU-c/suppression could be reduced by removing T cells from the patients' marrow before the co-culture experiments; 4) patients' marrow T cells showed significant CFU-c/inhibition against autologous as well as against allogeneic unrelated normal marrow cells; 5) irradiation with 1500 rads of T cells abrogated their suppressor activity; 6) the latter was found mainly in marrow T cells with IgG receptors (TG+ cells) as well as in the supernatant of marrow T cells cultured overnight; 7) TG+ cells derived from normal donors had no significant CFU-c/inhibitory activity against autologous or allogeneic marrow cells. Active myelosuppression would thus be detectable in patients with SAA in remission and would appear to be mediated by marrow T cells with IgG receptors.
mesh_terms: D000293:Adolescent; D000328:Adult; D000741:Anemia, Aplastic / Q000276:immunology*; D001854:Bone Marrow Cells; D002448:Cell Adhesion; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D005260:Female; D006410:Hematopoiesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D012397:Rosette Formation; D012995:Solubility; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology*