Changes in B cell and T cell subsets in bovine leukaemia virus-infected cattle

Abstract

Direct immunofluorescence and fluorescence-activated cell sorter techniques were used for the detection of surface immunoglobulin positive (SIg +) cells in peripheral blood lymphocytes (PBL's) of bovine leukaemia virus (BLV) infected cattle with or without persistent lymphocytosis (PL +, PL −) and in BLV-free cattle. The percentage of SIg + cells was more than twice as high in BLV +PL + cattle than in BLV-free and BLV +PL − cattle. Bovine T cells, and T cell subsets were identified indirectly by the same techniques using three monoclonal antibodies (MAb's) specific for all T cells (IL-A43), T helper (BoT4) cells (IL-A12) and T cytotoxic (BoT8) cells (IL-A17). The major histocompatibility complex (MHC) determinants of both class II (BoT4) and class I (BoT8) as well as all T cells were significantly reduced in BLV +PL + compared to BLV-free cattle. The actual decrease in the BoT8 cell subset or the dilution effect that would change effector: target cell ratio suggests that a resultant decrease in cytotoxic activity in BLV +PL + cattle may play an important role in the progress of BLV infection in cattle.