title: Isolation of leukaemia-associated inhibitor (LAI)-producing cells from normal peripheral blood.
abstract: LAI, leukaemia-associated inhibitor, has previously been shown to be produced by a subpopulation of null cells in myeloid leukaemia, and has the capacity to suppress the proliferation of normal granulopoietic stem cells, CFU-GM, in vitro. In the present study, low density mononuclear cells from normal peripheral blood were separated into adherent/non-adherent, phagocytic/non-phagocytic, T-lymphocytes/non-T cells, and Fc-receptor positive and negative cells in search for LAI-producing cells in normal blood. Cell fractions enriched for NK-cells were isolated from Percoll gradients and NK-activity and LAI-production were assayed in the different fractions. Anti-Leu-2, anti-Leu-3, and anti-HLA-DR were used to deplete mononuclear cells of cells positive for these monoclonals using a panning technique. It is concluded from these studies that normal LAI-producing cells belong to a non-adherent, non-phagocytic, non-T, non-B, Fc-receptor positive population which does not express NK-activity, and which is Leu-2, Leu-3 and HLA-DR negative. The results imply that LAI may be a novel feedback regulator of the proliferative rate of granulopoietic stem cells and that LAI is produced by a small subpopulation of cells in both blood and bone marrow.
mesh_terms: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface / Q000032:analysis; D002469:Cell Separation; D003115:Colony-Stimulating Factors / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000502:physiology; D003602:Cytotoxicity, Immunologic; D005293:Ferritins; D006098:Granulocytes / Q000166:cytology; D006412:Hematopoietic Stem Cells / Q000166:cytology; D006801:Humans; D007694:Killer Cells, Natural / Q000032:analysis; D009000:Monocytes / Q000032:analysis* / Q000145:classification; D011961:Receptors, Fc / Q000032:analysis; D013601:T-Lymphocytes / Q000032:analysis
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D003115:Colony-Stimulating Factors; D011961:Receptors, Fc; C020391:acidic isoferritin; D005293:Ferritins