θ Alloantigen on Mouse and Rat Fibroblasts

Abstract

THERE is increasing evidence that different cell types have important surface differences, some of which can be recognised immunologically. Such surface differentiation antigens can be useful markers for distinguishing and separating different kinds of living cells. In mice, for example, the θ alloantigen is present on thymocytes¹, thymus derived lymphocytes^{2, 3}, cells in the peripheral and central nervous system⁴ and epidermal cells⁵, while it is not found on bone marrow¹ or bone marrow-derived lymphocytes, plasma cells², granulocytes, macrophages or red blood cells^{1, 6}. There are two specificities, θC3H and θAKR, which are allelic products distributed reciprocally among the various mouse strains⁷. θAKR has recently been shown to be present also in some strains of rat, on thymus and lymph node lymphocytes and in the brain^{7, 8}. I describe here the expression of θ antigen on fibroblasts and some fibroblast-derived cell lines from mice and rats.