MONOCLONAL-ANTIBODY SPECIFICALLY REACTING AGAINST 73-KILODALTON HEAT-SHOCK COGNATE PROTEIN - POSSIBLE EXPRESSION ON MAMMALIAN-CELL SURFACE

The heat shock proteins (hsp) are regarded as being immunogenic to the animal hosts. Although certain hsp are suggested to be expressed on t he cell surface, further evidence for the cell surface expression of t hese proteins has been required. In this article we report the develop ment of a MAb NT22. This antibody reacted with ATP-binding proteins (w hich contain a large amount of 70-kDa hsp family) of HeLa cells, and w ith purified bovine 70-kDa hsp. It did not react with the E. coli lysa te, but clearly reacted with the recombinant rat hsc73. However, NT22 failed to react with hsp72. Furthermore, stress treatment of cells als o indicated that considerable amounts of NT22-defined antigen transloc ated into the nucleus from the cell cytoplasm. These results suggest t hat NT22 is a novel MAb that reacts specifically to the mammalian hsc7 3. Moreover, this antibody could detect the constitutive and stress-in duced cell surface expression of its relevant antigen. It is expressed preferentially on EBV-transformed B cell and certain epithelial cance r cell lines. However, resting B cells did not express this antigen on the cell surface. These data indicate that hsc73 could be expressed o n the cell surface of certain cells, and suggest that hsc73 may intera ct with the host immune system.