NS-6 (nervous system antigen-6): A new cell surface antigen of brain, kidney, and spermatozoa

Cell surface antigen NS-6 is identified on MUNTAD (mouse undifferentiated neural tumor, adeno virus induced) cells by complement-dependent cytotoxicity with anti-MUNTAD cell antiserum made in C3H/HeJ × C57BL/6J F1 mice. Quantitative absorption shows that this antigen (or antigens) is completely shared by normal brain, kidney, and spermatozoa. It is absent from liver, spleen, thymus, skin, and muscle. NS-6 is present on brain on embryonic Day 9, the earliest stage tested, and the amount of NS-6 on brain and on kidney does not change from birth to adulthood. Brains of many species, from fish to chicken and human, have antigen(s) which cross-react with NS-6. Within the mouse brain, this antigen shows no localization to any region, nor is it apparently restricted to any one cell type. This is consistent with NS-6 being an antigen of pluripotent neural progenitor cells which is passed to both neuronal and glial progeny. Expressed on two mouse and two human nervous system tumors, NS-6 is absent from all other tumors and cell lines tested.