HUMAN THYMOCYTE ANTIGEN DEFINED BY A HYBRID MYELOMA MONOCLONAL ANTIBODY

Spleen cells from a BALB/c mouse that immunized with human thymocytes and fused with the myeloma line P3-NS1/1 Ag 4.1. One of the resulting hybrid clones (NA1/34) secreted an antibody that was highly specific for human thymocytes. Of the thymocytes 85% expressed the antigen designated HTA1. There were an estimated 15 .times. 104 molecules of HTA1/cell, and it was therefore, a major surface molecule. The expression of this antigen on thymocytes appeared reciprocal to HLA, as recognized by another monoclonal antibody W6/32. Immunoprecipitated material from [125I]-labeled thymocyte membranes was analyzed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate which disclosed a single component of 45,000 MW.