OBJECTIVETo investigate the effect of in vivo administration of rhG-CSF and/or rhIL-11 on mice immune system function.

METHODST cell subgroups, suppressor T cells (CD8+ CD28-, CD4+ CD25+, CD3+ CD4- CD8- T cells), expression of CD28 on T cells, and spleen T cells intracellular IL4/IFN-gamma secretion were determined by multicolor flow cytometry. MTT was used to determine the T cell proliferation capacity and mixed lymphocyte reactions.

RESULTSIn vivo administration of cytokines decreased the percentage of lymphocytes (P < 0.05), rhIL-11 and rhG-CSF in combination significantly decreased the CD4+/CD8+ ratio and increased the percentage of CD8+ CD28- suppressor T cells compared to either cytokine alone (P < 0.01). There was no difference in the percentage of CD3+ CD4- CD8- and CD4+ CD25+ suppressor T cells between either of the cytokines. Furthermore, cytokines treatments significantly decreased the capacities of splenic T cells proliferation and the response to alloantigens compared with the PBS treatment (P < 0.05), the combination group being more significantly decreased (P < 0.01). And cytokines treatment significantly decreased the production of IFN-gamma and increased the production of IL-4 compared with the PBS treatment(P < 0.05). The ratio of IFN-gamma/IL-4 were significantly decreased after the combination compared with either of them alone.

CONCLUSIONThe combination of rhIL-11 and rhG-CSF is potentially synergistic in the induction of immune tolerance by their effects on the proliferation capacity and function of T lymphocytes.