Association of thy-1 cell surface differentiation antigen with certain connective tissues in vivo.

The cell surface differentiation antigen, Thy-1, has been demonstrated by immunofluorescence to be associated with some collagen-based connective tissue. In the rat, the basement membrane of kidney collecting tubules of certain blood vessels, reticulin of the lamina propria, loose connective tissue in the dermis, and collagen fibres within certain nerve cell tumours, bear the antigen. Other, apparently similar, connective tissue (especially that of muscle and liver) lacked Thy-1. In the mouse, only the connective tissue of the skin was found to bear the antigen. The possible origin of this extracellular Thy-1, and its implications for the function of the molecule, are discussed.