TCR GAMMA-DELTA(+) CELLS ARE PROMINENT IN NORMAL BOVINE SKIN AND EXPRESS A DIVERSE REPERTOIRE OF ANTIGEN RECEPTORS

More than 80% of T cells in bovine skin localized in the superficial 0 .5 mm Or the dermis. Only 3% occurred within the epidermis or made con tact with the stratum basale while the remainder occupied deeper derma l sites, The gamma delta T-cell receptor (TCR) was expressed by 44% of T cells in skin and 39% and 35% expressed, respectively, the CD4 and CDS markers, Same cells co-expressed CD8 and the gamma delta TCR, A hi ghly diverse repertoire of gamma delta TCR was expressed in skin due m ainly to the usage of multiple V delta segments and to extensive seque nce variation at the junctions of both TCR gamma and TCR delta chains. However, a single receptor isotype was used. Transcripts encoding sev eral new components of the bovine gamma delta TCR were identified, inc luding three new V gamma segments, the C gamma 5 region and 13 new fun ctional V delta segments. Taken together with earlier findings, these results emphasize that ruminant gamma delta T cells express exceptiona lly diverse antigen receptors and suggest they may have a more elabora te recognitive capacity than do their counterparts in other species.