title: Beta-2 microglobulin-free HLA class I heavy chain (FHC) A3 and/or A30 soluble products contribute only minimally to serum FHC expression.
abstract: No monoclonal antibodies (mAbs) are presently available to measure the total amount of beta2-microglobulin-free HLA class I heavy chain (FHC) in sera. The available ELISA-based double determinant immunoassay (DDIA), established to measure FHC, uses two mAbs (TP25.99 and HC-10) that recognize a monomorphic determinant expressed on all HLA-B/C FHC products and a determinant expressed only on some HLA-A FHC products. This restricted reactivity implies that, in addition to HLA-B/C, HLA-A FHC products are also detected in individuals bearing HLA A3 and/or A30 allotypes. The aim of this study was to establish whether such restriction results in the detection of low FHC levels in individuals lacking HLA A3 and/or A30 allospecificities. The FHC mean concentration (+/- SD) in 294 healthy blood/bone marrow donors (HBDs) was 0.24 (+/- 0.2) mg/l. The grouping of HBDs according to their HLA-A FHC product reactivity with one, both or no mAbs did not result in any statistically significant differences (Mann-Whitney test: P > 0.05) between their median FHC concentrations. Since the absence of differences in their FHC levels was not attributable to a difference in the percentage distribution of HLA allotypes associated with high or low HLA-B/C FHC expression, our results indicate that FHC HLA A3 and/or A30 products detected in DDIA by these two mAbs only minimally contribute to FHC serum expression and that the assay is not limited by the failure to detect HLA-A FHC products in A3- and/or A30- individuals.
mesh_terms: D004797:Enzyme-Linked Immunosorbent Assay; D015234:HLA-A Antigens / Q000032:analysis / Q000097:blood / Q000276:immunology*; D015791:HLA-A3 Antigen / Q000032:analysis / Q000097:blood / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000032:analysis / Q000097:blood / Q000276:immunology*; D006801:Humans; D007518:Isoantibodies / Q000097:blood / Q000276:immunology*; D001613:beta 2-Microglobulin / Q000097:blood
chemical_list: D015234:HLA-A Antigens; C069526:HLA-A*30 antigen; D015791:HLA-A3 Antigen; D015395:Histocompatibility Antigens Class I; D007518:Isoantibodies; D001613:beta 2-Microglobulin