We have applied a double-determinant immune assay (DDIA) to measure soluble β2-microglobulin (β2-μ)-free HLA class I heavy chains in serum. The mean concentration of β2-μ-free HLA class I heavy chains in serum from 120 healthy subjects was 0.21 ± 0.24 μg/ml. The individual serum levels of β2-μ-free HLA class I heavy chains had a wide distribution, did not seem to be related with HLA phenotype, were stable over time and did not change with age. The serum levels of soluble β2-μ-free HLA class I heavy chains did not correlate with those of soluble β2-μ-associated HLA class I heavy chains, suggesting that their release is independently regulated. Three forms of soluble β2-μ-free HLA class I heavy chains, with apparent molecular masses of 44, 39 and 37-35 kD, respectively, circulate in human serum. These results provide a useful background to assess the serum level of soluble β2-μ-free HLA class I heavy chains in pathological conditions and to evaluate their putative immunoregulatory function.
- β-μ-free HLA class I heavy chains
ASJC Scopus subject areas
- Cell Biology