Requirement for LYT-2/3 Molecules on Allospecific Cytolytic T Lymphocyte Clones is Dependent Upon Target Cell Antigen Density
The Lyt-2/3 antigenic complex in the mouse (1) is expressed preferentially on cytolytic T lymphocytes (CTL) and appears to be involved in the recognition of target cells (2,3). In the course of investigating this phenomenon at the clonal level, we observed that individual CTL clones vary greatly in their requirement for Lyt-2/3 molecules in killing. Thus some CTL clones lose cytolytic activity when treated with monoclonal antibodies (MAbs) directed against Lyt-2/3 (4) or with doses of trypsin which selectively cleave the Lyt-2/3 antigenic determinant from the cell surface (5), whereas other clones are resistant to either treatment. Based on these findings, we (6) and others (7,8) have postulated that the role of the Lyt-2/3 molecules may be to facilitate and/or stabilize the interaction between CTL and their target cells. According to this model, the degree to which Lyt-2/3 molecules are required for effective CTL-target cell binding would be inversely related to the intrinsic affinity of the CTL antigen receptor (6).
KeywordsTarget Cell Antigenic Determinant Cytolytic Activity Clonal Heterogeneity Clonal Level
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