Reaction patterns of monoclonal antibodies to HLA-G in human tissues and on cell lines: A comparative study

We compared the immunohistochemical reaction patterns of HLA-G-specific ant ibodies 87G, 4H84, G233, 16G1, and BFL.1 on human placentas under three dif ferent preparative conditions and on cryosections of other human tissues. H uman and murine cell lines, either naturally expressing or transfected with HLA-e,:were analyzed for their reaction patterns by immunocytochemistry an d flow cytometry. Antibodies HCA2, TP25.99, W6/32 to classical HLA class I, anti-beta (2)-m and various non-HLA-G expressing cell lines were used as c ontrols. The binding ability of the antibodies depends on the histotechnica l procedure used. 4H84 and HCA2 bind to HLA-G despite aldehyde fixation and also paraffin embedding. 87G does not bind HLA-G in studies involving fixa tion with aldehydes. G233 labels HLA-G in aldehyde fixed but not paraffin e mbedded tissues. By immunocytochemistry HLA-G2 is merely detected with anti bodies 4H84 and HCA2. MAb 16G1 binds to HLA-Gsol transfected cell Lines onl y. The HLA-G specificity of mAb BFL.1 was considered as doubtful because it failed to react with most of the HLA-G transfected cell lines. Binding of 87G to the surface of monocytes or U-937 cells stimulated with IFN-gamma an d GM-CSF is an Fc-receptor mediated phenomenon. (C) American Society for Hi stocompatibility and Immunogenetics, 2000. Published by Elsevier Science In c.