Decreased expression of L-selectin (CD62L) on lymphocytes in enzootic bovine leukaemia.
Expression of L-selectin was determined by single- and two-colour immunofluorescence on granulocytes, peripheral blood mononuclear cells (PBMC) and blasts of bovine origin by means of a monoclonal antibody IVA94 which recognizes bovine L-selectin (CD62L). Cells were separated from peripheral blood of healthy cattle and colleagues infected with bovine leukaemia virus (BLV). BLV-infected animals comprised lymphocytotic and non-lymphocytotic cows. L-selectin was expressed on 90-98% of granulocytes in all tested animals. The percentage of PBMC expressing L-selectin was lower in cattle with persistent lymphocytosis than in non-lymphocytotic or BLV-free cattle, and inversely correlated with lymphocyte counts. The ratio of B lymphocytes stained for L-selectin was significantly decreased from 60.2 +/- 1.9% in BLV-free cattle to 43.8 +/- 3.6 and 22.5 +/- 5.7% in non-lymphocytotic and lymphocytotic cattle, respectively. B-lymphocytes stained for L-selectin exhibited about 50% reduction in L-selectin expression in BLV-infected cattle compared with BLV-free cattle, as judged by the mean fluorescence intensity (MFI). The percentage of L-selectin-positive PBMC not bearing surface immunoglobulin M (predominantly T lymphocytes) was comparable in BLV-free and BLV-infected cattle. However, L-selectin expression on T lymphocytes was reduced (about 50%) in BLV-infected cattle, as judged by the MFI. We suppose that BLV infection results in a decreased L-selectin expression on lymphocytes, and accordingly, it may contribute to deregulation of the host immune system.
Dusinský
R
R
Institute of Veterinary Microbiology and Immunology, University of Milan, Italy. dusinsky@ubgz.savba.sk
Bardotti
M
M
Ponti
W
W
D000818:Animals; D000911:Antibodies, Monoclonal; D002417:Cattle; D016583:Enzootic Bovine Leukosis / Q000276:immunology* / Q000821:virology; D005434:Flow Cytometry / Q000662:veterinary; D015973:Gene Expression Regulation, Leukemic; D019041:L-Selectin / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D001909:Leukemia Virus, Bovine / Q000235:genetics / Q000276:immunology*; D008214:Lymphocytes / Q000276:immunology*
D000911:Antibodies, Monoclonal; D019041:L-Selectin