OX-40 antibody enhances for autoantigen specific V beta 8.2(+) T cells within the spinal cord of Lewis rats with autoimmune encephalomyelitis

The V beta 8.2 T cell receptor (TCR) component is the predominant VP gene product associated with antigen specific CD4(+) T cell response to the major encephalitogenic epitope of myelin basic protein (MBP) in Lewis rats, Lewis rats were actively immunized with MBP in complete Freund's adjuvant and the V beta 8.2 positive and negative cells were analyzed for IFN-gamma mRNA production and OX-40 cell surface expression during the onset of EAE, The V beta 8.2(+) T cells isolated from the spinal cord produced the majority of mRNA for IFN-gamma and also showed a marked enhancement for OX-40 expression compared to V beta 8.2(+) T cells isolated from the lymph nodes. Only a fraction of IL-2 receptor positive T cells examined ex vivo from the inflammatory compartments co-expressed the OX-40 antigen, These results suggested that OX-40 cell surface expression could be used to identify and isolate the most recently activated T cells ex vivo. OX-40 + T cells isolated from the spinal cord were highly enriched for the V beta 8.2 T cell receptor component compared to OX-40(-) or unsorted spinal cord lymphocytes, OX-40(+) T cells isolated from the spinal cord had an enhanced response to MBP, whereas OX-40(+) cells isolated from the lymph nodes responded to both MBP and purified protein derivative. These data suggest that activated T cells can be isolated and characterized with the OX-40 antibody which only respond to the antigens present at the local site, The data also imply that isolation of OX-40(+) T cells will be useful in identifying VP biases and autoantigen specific cells within inflamed tissues even when the antigen specificity is unknown. (C) 1996 Wiley-Liss, Inc.*