Cellular immunity mediated by nonspecific cytotoxic cells (NCC) in catfish and by natural killer cells (NK) in mice and humans will be analyzed and compared. This will be acommplished because monoclonal antibodies have been derived against the NCC and NK cell receptor that inhibit cytolytic function. Using these monoclonals as biological probes, studies will be carried out to define: (a) the species distribution and expression of these effector cell determinants; (b) the biological effects of these determinants on immune cell function; (c) and it will be determined if any of these molecules are similar to any known structures against which phenotyping reagents are available. At the biochemical level, attempts will be made to determine the primary structure of these molecules. Additional studies will determine if these ligands act as signal transducing structures; and if cellular loss variants or if substitution/reconstruction techniques are appropriate to determine if these antigens affect immune function(s). The final phase of the grant will utilize techniques at the molecular level to attempt identification and mapping of the genes encoding these determinants. Attempts will also be made to isolate and to obtain cloning and expression vectors of these genes. Studies proposed in this grant will contribute significant knowledge to the field of comparative immunology. More important, data obtained using the effector cell monoclonals will address a major question in NK cell biology: What is the recognition structure on NK cells? The monoclonals already derived inhibit function, bind specifically, and act across species lines. To achieve these aims, the highly sensitive techniques of: flow cytometry, immune precipitation and Western blotting, biosynthetic labeling and pulse-chase experiments will be utilized to characterize the biochemistry of these molecules. Various in vitro cytotoxicity experiments including inhibition/augmentation studies and cell surface epitope modulation experiments will be used to characterize biological functions. Signal transducing functions (calcium mobilization, protein phosphorylation) will be ascertained in order to detemine the role(s) of these antigens in the activation processes of these cells.
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