DECREASED PRODUCTION OF CYTOKINES AFTER CYTOMEGALOVIRUS-INFECTION OF MARROW-DERIVED STROMAL CELLS

Cytomegalovirus (CMV) infection is frequently associated with graft fa ilure in bone marrow transplant patients; the pathogenesis of this mye losuppression in not clearly understood. We have previously documented that CMV-induced myelosuppression is related to an alteration of the marrow microenvironment. To further investigate the effect of CMV on s tromal cell function, conditioned media (CM) from CMV-infected or unin fected stromal cells were tested for their capacity to promote the gro wth of granulocyte/macrophage colony-forming cells (CFU-GM) and for th eir concentration in colony-stimulating factors (CSFs) such as interle ukin-3 (IL-3), IL-6, granulocyte-macrophage and granulocyte colony-sti mulating factors (GM-CSF and G-CSF). CM from CMV-infected stromal cell s failed to sustain granulocyte-macrophage colony-forming unit (CFU-GM ) growth. The production of IL-6, GM-CSF, and G-CSF, measured by enzym e-linked immunosorbent assay (ELISA), was 21,150 +/- 3392, 57 +/- 15, and 2340 +/- 717 pg/mL, respectively, in CMV-infected stromal cells st imulated by lipopolysaccharide (LPS) and was significantly decreased ( p<0.01) from the control values (177,138 +/- 98,692, 113 +/- 20, and 5 533 +/- 1306 pg/mL). These results suggest that the myelosuppressive e ffect of CMV is primarily due to a lack of CSF production. To further document this hypothesis, primitive marrow progenitor cells (blast col ony-forming cells [Bl-CFC]) cultured on CMV-infected stromal layer hav e been grown in the presence of IL-3 (20 ng/mL), IL-6 (20 ng/mL), GM-C SF (40 ng/mL), and G-CSF (50 ng/mL). Used alone, all these CSFs partia lly reverse the CMV-induced inhibition of Bl-CFC growth; the combinati on of these CSFs completely restores normal Bl-CFC values. These data strongly suggest that CMV-induced myelosuppression is related to the l ack of CSF production by the cells of the marrow microenvironment.