Expression of Histocompatibility-2 antigens on cultured cell lines derived from mouse blastocysts

Four cell lines derived from four-day-old SWR/J♀×SJL/J♂ mouse blastocysts have been assayed for their expression of H-2 specificities with pauci- and monospecific H-2 typing sera. Direct microcytotoxicity and indirect absorption studies reveal many deviations from expected expression of particular H-2 specificities based on the cell lines' genotypes and on H-2 typing of adult F₁ lymphocytes. No pattern of selective expression of public or private specificities of D-end or K- end specificities or of inclusion groups was noted. At least one public or private specificity of each D^q, K^q, D^s, and K^s region is present, indicating that part of each product is expressed. The partial expression of H-2 specificities is discussed structurally, in terms of how incomplete H-2 molecules may be present on the cell surface, and developmentally, in terms of how the variant H-2 specificities may be involved in cell positioning during ontogenesis.