title: T-derived colony-inhibiting activity: partial characterization and mechanism of action.
abstract: A soluble inhibitor of granulocyte macrophage colony growth, to which we shall refer to as T-derived colony-inhibiting activity (Td/CIA), was obtained from the supernatant of T cells from 5 healthy donors and 5 patients with severe aplastic anemia (SAA) in remission, following immunosuppressive therapy. The supernatants were purified by an ACA 44 column and the suppressor activity found in fractions of 70,000-80,000 daltons. Experiments were then performed to test for endogenous productions of Td/CIA in normal marrow cells (NBM), reversibility of suppression, and competitive inhibition with human placenta-conditioned medium (HPCM). The results of this study can be summarized as follows: the endogenous production of Td/CIA can be elicited by addition of mitogens to NBM, and is prevented if the marrow is T-depleted or treated with cyclosporin A; suppression is completely reversible if Td/CIA is removed from NBM by washing at 1, 48, 72 and 96 h; CFU-c which have been exposed to Td/CIA once, and freed from Td/CIA by washing, are still sensitive to a second exposure of Td/CIA; there is no clear competitive inhibition between Td/CIA and HPCM. These experiments represent an in vitro model of a lymphokine-mediated regulation of CFU-c growth not associated with death of progenitor cells.
mesh_terms: D001854:Bone Marrow Cells; D002455:Cell Division; D002478:Cells, Cultured; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D008222:Lymphokines / Q000302:isolation & purification* / Q000502:physiology; D008970:Molecular Weight; D011506:Proteins / Q000302:isolation & purification* / Q000502:physiology; D013601:T-Lymphocytes / Q000166:cytology / Q000502:physiology*
chemical_list: D008222:Lymphokines; D011506:Proteins; C016313:colony inhibiting factor