title: Alloantigenic recognition of artificial glycosyl phosphatidylinositol-anchored HLA-A2.1.
abstract: Alloantigen presentation by GPI-reanchored variants of the human class I MHC molecule HLA-A2.1 was studied in human cellular systems. To this end, we generated chimeric coding sequences for two GPI-modified HLA-A2.1 heavy chain derivatives. In these chimeras, the coding sequence for the HLA-A2.1 heavy chain was fused in-frame to alternative overlapping sequences from the 3'-end of human DAF containing the GPI-modification signal sequence. The encoded polypeptides HLA-A2.1:DAF-S and HLA-A2.1:DAF-L differed by 53 amino acids of additional DAF sequence in the latter. Both were detected on stably transfected C1R cell surfaces by HLA-A2.1-specific mAb, and their GPI-modification was confirmed by PI-PLC enzymatic cleavage. Immunoprecipitation analysis of surface-biotinylated C1R transfectants revealed heterodimeric association for both HLA-A2.1:DAF-L and HLA-A2.1:DAF-S heavy chains with beta 2m. Alloantigenic stimulation by, and cytotoxic recognition of, both HLA-A2.1:DAF-S/C1R and HLA-A2.1/CIR cells was observed; however, HLA-A2.1:DAF-L/C1R cells could not serve as allostimulators or allotargets. These findings establish that polymorphic human class I MHC molecules can function, when artificially GPI-reanchored, as alloantigenic targets. Moreover, the data suggest that the sequence bridging the HLA-A2 extracellular domain and the membrane can influence alloantigenic presentation.
authors.affiliation: Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106-4943.
authors.forename: J H
authors.initials: JH
authors.lastname: Huang
authors.forename: N S
authors.initials: NS
authors.lastname: Greenspan
authors.forename: M L
authors.initials: ML
authors.lastname: Tykocinski
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000276:immunology*; D001483:Base Sequence; D003001:Cloning, Molecular; D005434:Flow Cytometry; D017261:Glycosylphosphatidylinositols / Q000737:chemistry / Q000276:immunology*; D015789:HLA-A2 Antigen / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007519:Isoantigens / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011993:Recombinant Fusion Proteins / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D017261:Glycosylphosphatidylinositols; D015789:HLA-A2 Antigen; D007519:Isoantigens; D011993:Recombinant Fusion Proteins