Splenic granulocytopoiesis and production of colony-stimulating activity in lymphoma and leukemia

Spleen cell production of granulocyte-macrophage colony stimulating activity (CSA) and colony forming capacity (CFU-GM) from 59 patients with Hodgkin's and non-Hodgkin's lymphoma, acute (AML) and chronic myeloid leukemia (CML), and control subjects was quantified to evaluate local cellular potential for modulating splenic granulocytopoiesis. Mononuclear spleen cell conditioned media stimulated myeloid CFU-GM by human nonadherent marrow target cells. In contrast to conditioned media produced by marrow and peripheral blood cells, the vast majority of spleen CSA was generated by nonadherent lymphoid cells rather than adherent monocytic cells. The nonadherent cells producing CSA were non- T cells (assessed by sheep erythrocyte rosetting), with 98% +/- 2% CSA produced by the nonrosetted fraction (B lymphocytes and null cells), and had a peak density heavier than that of the adherent spleen CSA- producing cells. Dose response curves demonstrated significantly increased cellular CSA production from patients with lymphomas and AML in remission. In a high proportion of patients, foci of immature granulocytic cells were found by specific cytochemical staining of histologic sections of spleens. A limited degree of splenic granulocytopoiesis was demonstrated morphologically and by CFU-GM incidence. CSA was not detectable in conditioned medium prepared from nonadherent spleen cells from 5 patients with CML, due to a nondialyzable substances(s) produced by the nonadherent cells which inhibited normal CFU-GM response to CSA. The high CFU-GM incidence and extensive leukemic granulocytopoiesis present in the CML spleens suggests diminished effect of this inhibitor on leukemic as opposed to normal granulocytic precursor cell proliferation.