Serum levels of beta-2-microglobulin-free heavy chain of HLA class I antigen in healthy individuals: relationship to their class I allotype.
An ELISA-based double determinant immunoassay has been established to measure the soluble beta2-microglobulin (beta2m)-free heavy chain (FHC) of the HLA-B, -C (and HLA-A3, -A28 and -A30) class I molecular complex in sera from 212 HLA-typed healthy unrelated individuals. FHC was calculated by means of a standard curve constructed using serial concentrations of beta2m-associated HLA-class I heavy chain (HLA-I)/FHC purified from cultured human lymphoid cell C1R-sB7-supernatant. The mean FHC concentration (+/-SD) was 0.25 mg/l (+/-0.2). Its median concentration did not statistically differ between males and females, though the male/female ratio was greater in the high secretor (FHC >0.45 mg/l; mean + 1SD) than in the low secretor group (FHC < 0.05 mg/l; mean - 1SD). FHC < 0.05 mg/l was statistically (Fisher's exact test) associated with HLA-B17 (p = 0.003); FHC > 0.45 mg/l was statistically associated with HLA-B35 (p = 0.003) and -Cw4 (p = 0.002). None of these allele-positive groups showed a mean FHC concentration 1.5 times higher than that of the corresponding allele-negative ones. This allotype-dependent HLA-B and C FHC enhancement was less marked than that previously reported for HLA-I in individuals carrying HLA-A9 (and its splits). These results indicate that FHC could be a more valuable marker when its levels are compared among individuals carrying different allotypes. Moreover the lack of correlation between FHC and HLA-I levels measured in 52 HLA-A3, -A28 or -A30 positive individuals suggests that the two molecules may be regulated by different metabolic pathways and their serum expression may have a different biological significance.
Perosa
F
F
Department of Biomedical Sciences and Human Oncology, University of Bari Medical School, Italy.
Prete
M
M
Luccarelli
G
G
Favoino
B
B
Ferrone
S
S
Dammacco
F
F
D000483:Alleles; D000818:Animals; D000911:Antibodies, Monoclonal; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000592:standards; D006680:HLA Antigens / Q000097:blood* / Q000235:genetics; D015395:Histocompatibility Antigens Class I / Q000097:blood* / Q000235:genetics; D006801:Humans; D051379:Mice; D012015:Reference Standards; D012995:Solubility; D001613:beta 2-Microglobulin / Q000097:blood
D000911:Antibodies, Monoclonal; D006680:HLA Antigens; D015395:Histocompatibility Antigens Class I; D001613:beta 2-Microglobulin