Sensitivity of H–2-less target cells and role of H–2 in T-cell-mediated cytolysis

Abstract

THERE is no definitive teleological interpretation of the involvement of H–2 determinants in the recognition by mouse cytolytic T cells of various non-H–2 antigens^1,2. While it is generally believed that T-cell immunity against non-H–2 structures (determined, for example, by infectious agents) may benefit from the known special reactivity of T cells against non-self H–2, other interpretations have been proposed, such as the possibility that H–2 is necessary for cytolysis at a postrecognition stage as the “weak point” of the target-cell surface³. A prediction of this hypothesis is that target cells devoid of H–2 should be resistant to T-cell-mediated cytolysis. We have tested this prediction using male germinal cells, embryonal carcinoma and virus-transformed testicular cells as targets, in the presence of the lectin concanavalin A (con A). Con A binding apparently by-passes⁴ the normal recognition system, so that lack of recognition of H–2 on H–2-less target cells would not be a limiting factor for cytolysis. We found that H–2-less embryonal carcinoma cell lines, including one with barely detectable levels of F9 antigen, were sensitive to lysis, strongly suggesting that at a postrecognition stage H–2 is not required for T-cell-mediated cytolysis.