Detection of anti-HLA-F antibodies in sera from cancer patients.

BACKGROUND We previously reported that a Q5 gene product (Q5 antigen) on the surface of tumor cells caused humoral immune reaction in syngeneic tumor-bearing mice. Transcripts of the Q5 gene were observed in various tumor cells. The human counterpart of the Q5 gene has not been clarified yet. MATERIALS AND METHODS Transcripts of human class Ib genes in various human tumor cell lines were analyzed by the RT-PCR method. Whether anti-HLA-F antibodies were present in sera from cancer patients was investigated through Western blotting with recombinant HLA-F as an antigen. RESULTS Transcripts of the HLA-F gene were produced by various tumor cell lines. In addition, anti-HLA-F IgG was present in the sera derived from various types of cancer patients (26 positives / 42 tested), but not in the sera derived from healthy donors (0 / 20). CONCLUSION Anti-HLA-F antibodies should be further investigated as possible diagnostic tumor markers.