ANALYSIS OF THE PHENOTYPE AND PHAGOCYTIC-ACTIVITY OF MONOCYTES MACROPHAGES FROM CATTLE INFECTED WITH THE BOVINE LEUKEMIA-VIRUS/

The bovine leukaemia virus (BLV) is a retrovirus that infects mainly B lymphocytes of cattle, but proviral DNA can also be isolated from mon ocytes/macrophages. This study investigated the effect of BLV infectio n on surface antigens on freshly isolated peripheral blood monocytes a nd cultured monocyte-derived macrophages, with and without lipopolysac charide (LPS) stimulation. The effect of BLV infection on phagocytic a ctivity of CD14(+) monocytes was also assessed. The percentage of mono cytes expressing the surface antigens CD11b, CD32 (Fc gamma RII), MHC class II and the surface antigen recognised by mAb DH59B were increase d in BLV-positive cattle. In contrast, expression intensity of all mar kers was low in samples from BLV-positive cattle. CD14(+) monocytes fr om BLV-positive cattle showed less Fc gamma-receptor-mediated phagocyt osis compared to monocytes from BLV-negative cattle. After 7 days in c ulture, there was evidence for shedding/downregulation of surface anti gens on monocyte-derived macrophages, in particular on cells from BLV- positive cattle. LPS stimulation decreased the percentage of cells exp ressing the measured markers in monocyte-derived macrophages taken fro m BLV-negative cattle, but not in cultures derived from BLV-positive c attle. The results provide further evidence for an altered function of monocytes and macrophages in BLV-infected cattle. (C) 1998 Elsevier S cience B.V.