A STUDY ON LYMPHOCYTE-ACTIVATION IN MAEDI-VISNA VIRUS-INDUCED PNEUMONIA

The stage of activation of bronchoalveolar lavage fluid (BALF) lymphoc ytes and peripheral blood lymphocytes (PBL) from maedi-visna virus (MV V) infected (n=7) and control (n=7) sheep was investigated by assessin g four parameters of lymphocyte activation; lymphocyte size and comple xity, loss of CD5(+) T cells, expression of cell surface interleukin-2 receptor (IL-2R) and expression of DR and DQ MHC Class II molecules. BALF lymphocytes from MVV-infected animals had a significant loss of C D5(+) lymphocytes (P < 0.05) and upregulation of DR and DQ MHC Class I I molecules compared with controls, consistent with BALF lymphocyte ac tivation. No changes in cell size and complexity or expression of IL-2 R were observed. No evidence of PBL activation was detected. These fin dings suggest an impaired BALF lymphocyte activation during MVV infect ion.