THE DISTRIBUTION OF LYMPHOCYTE SUBPOPULATIONS IN NORMAL AND ACANTHOTIC OVINE SKIN

The prevalence and distribution of lymphocyte subpopulations in normal and acanthotic ovine skin were investigated using monoclonal antibody immunocytochemistry. CD8(+) cells were predominant in the epidermis o f both normal and acanthotic skin, but were CD8(+) cells, CD4(+) cells and T19(+) cells infrequent in normal epidermis, Within the dermis of normal skin, there were significantly greater numbers of CD4(+) and T 19(+) cells situated around the superficial dermal vessels than in any other region examined. The majority of the CD8(+) cells adjoined vess els, but the proportion that did not was greater for CD8(+) than for C D4(+) or T19(+) cells. The CD4(+) and CD8(+) subsets were represented equally in adnexa. T cells were of memory phenotype, B cells and naive T cells, both of which express the CD45RA antigen, were rarely seen a nd tended to be associated with vessels in both normal and acanthotic skin, None of the T19(+) cells (which are gamma delta(+)) resembled th e dendritic gamma delta cells seen in murine epidermis. Acanthotic ski n was strikingly different to normal skin, There was a greater abundan ce of T cells, particularly CD4(+) cells, in acanthotic epidermis and the numbers of CD8(+) and T19(+) cells, and to a greater extent CD4(+) cells, were greater at the dermal-epidermal junction. There were more CD4(+) and CD8(+) cells in the superficial dermal stroma of acanthoti c skin. Within the dermis of acanthotic skin, T cells were concentrate d near vessels but the apportioning of T cells between stromal/adnexal and vessel-associated sites differed from normal. Such observations s uggest that migration away from perivascular sites and into the stroma may be controlled separately for subregions of skin and for each T ce ll subset. The role of this altered nonrandom migration of T cells in skin chronically exposed to ultra violet radiation is uncertain.