NATURAL-KILLER CLONES RECOGNIZE SPECIFIC SOLUBLE HLA CLASS-I MOLECULES

Enhancement of major histocompatibility complex (MHC) class I expressi on leads to protection from natural killer (NK) cell recognition in se veral systems. MHC class I gene products are released from the cell su rface and can be found in sera as soluble forms. To investigate the po ssible immunoregulatory role of soluble KLA (sHLA) in NK cell-target r ecognition, several sHLA antigens were studied for their ability to in duce NK cell cytotoxicity modulation. NK cell-target recognition was i nhibited by the addition of sHLA during the cytotoxicity assay. Our re sults indicate that sHLA molecules can down regulate NK killing al the effector level. Moreover, different NK clones are able to specificall y recognize different sHLA antigens. Kp43 molecules seem to be involve d in the NK recognition of sHLA-B7.