Assessment of the role of M-CSF in expansion of CD 14 + CD 16 + blood monocytes in patients undergoing haemodialysis

ABSTRACT

The immunodeficiency of patients with chronic renal failure [CRF] is related to multiple and complex alterations of the cytokine network and of its target cells such as T or B lymphocytes, monocytes, fibroblasts or endothelial cells. Chronic activation of monocytic functions is a key factor in these immunological disorders. A normal subpopulation of blood monocytes coexpressing CD 16 antigen and low level of CD 14 antigen [CD 14+ CD16+] has recently been identified. In this study, we measured the plasma levels of some relevant haemopoietic growth factors and cytokines in 32 patients suffering from CRF who were undergoing haemodialysis and 12 healthy controls, using an ELISA technique. The plasma levels of macrophage - colony stimulating factor [M- CSF] were significantly increased in patients compared to controls [p < 0.001], while the increase in granulocyte macrophage colony stimulating factor [GM - CSF] and interleukin 10 [IL - 10] was insignificant [p > 0.05]. We also examined the immunophenotype of blood monocytes in haemodialysed patients using two - colour immunofluorescence flow cytometry. A significant increase in the percentage and absolute number of CD 14+ CD 16+ monocytes was noted in patients compared to controls [p<0.00l]. On the other hand, the percentage of CD 14++ CD 16- regular monocytes was slightly but significantly decreased [p < 0.01], although their absolute number did not differ significantly [p > 0.05]. Significant correlation was detected between plasma levels of M - CSF and the number of CD 14+ CD 16+ monocytes.Our results suggest that increased endogenous levels of M-CSF plays a major role in the chronic activation of monocyte subpopulations and may be responsible for the expansion of CD 14+ CD 16+ blood monocytes which leads to multiple metabolic, haematologic and immunologic defects in CRF patients under haemodialysis