H-Y antigen negative patients with testicular tissue and 46,XY karyotype

H-Y antigen could not be detected on lymphocytes from two male pseudohermaphrodites with 46,XY karyotypes and testicular tissue. One of the patients had additional assays performed on fibroblasts grown from the skin, and the gonadal ridge--these were also negative. The H-Y antiserum was raised in rats, with Raji cells the target of cytotoxicity tests. In these patients. the substance that promoted testicular differentiation does not have serologic H-Y antigen detectable by the assay used. It appears that H-Y antigen that is commonly measured in neutralization reactions may not be the only form of testicular organizing factor present.