Lack of dendritic Thy-1⁺ epidermal cells in mice with severe combined immunodeficiency disease

C.B-17 scid (severe combined immunodeficiency disease) mice were used to evaluate the relationship of dendritic Thy-1⁺ epidermal cells (EC) to T lymphocytes (deficient in scid) and to NK cells (replete in scid). Epidermis from scid mice was deficient in dendritic Thy-1⁺ cells as determined by immunofluorescent staining of epidermal whole mounts. Similarly, epidermal cell suspensions from scid mice failed to proliferate in response to Con A, as compared with epidermal cell suspensions from C.B-17 control mice. Transplantation of normal bone marrow into scid mice reconstituted morphologically identifiable dendritic Thy-1⁺ EC in whole mounts, as well as Con A responsiveness of EC suspensions, thus indicating that the deficiency in dendritic Thy-1⁺ in scid mice is at the precursor level. These studies demonstrate that Thy-1⁺ EC are more closely related to T lymphocytes than to NK cells.