Cloning of cDNAs Encoding Molecules Involved in the Recognition of Allograft by Macrophage

Abstract

Allograft (e.g., skin and Meth A tumor)-induced macrophage (AIM) exhibits a unique (cell-to-cell contact-dependent and TNF-α- and NO-independent) cytotoxic activity against the allograft. In the last meeting, we reported that two cDNA clones (#15-4-4 and #12-4-5) were isolated by the expression cloning method using neutralizing monoclonal antibodies to AIM cytolysis, that the #15-4-4 cDNA (261bp fragment) had a region homologous to potential phospholipid-transporting ATPase IIb, and that the protein encoded by #12-4-5 cDNA (551bp fragment) was homologous to a functionally as yet unknown protein. Here, we partially characterized the nature of protein encoded by #12-4-5 cDNA. Although RT-PCR showed that the cDNA was expressed strongly in AIM and weakly in Mac-1⁺ cells (peripheral blood) and F4/80⁺ cells (transplantation site) with a size of 2.3kb, Northern blot analyses revealed the AIM-specific expression of #12-4-5 cDNA with smaller sizes of alternatively spliced valiants. Of particular interest, the protein expressed as a capsid fusion protein on T7 phages did bind to H-2K^d (a mouse MHC of allograft) tetramer, suggesting that the protein encoded by #12-4-5 cDNA might be a recognition molecule for allogeneic MHC. [Jpn J Physiol 54 Suppl:S79 (2004)]