Reexpression of a T/t-complex antigen (t12) in thymocyte × embryonal carcinoma cell hybrids

Abstract

Hybrids between PCC4 aza 1 teratocarcinoma cells and thymocytes from an adult +/t¹² mouse are phenotypically embryonal carcinoma cells. They express the t¹² antigen and do not express detectable H-2 antigens. Normally t¹² is only expressed early in development and on male germ cells. Thus, the thymocyte genome is reprogramed such that adult thymocyte H-2 antigen is turned off but the thymocyte genome participates in the embryonal cell phenotype by reexpressing an embryonic antigen long silent in the adult. The expression of the t¹² embryonic antigen represents the first example of the activation of a gene in somatic cell hybrids that is expressed only temporally in development.