No abstract

Soluble HLA class I (sHLA-ABC) and class II (sHLA-RQP) molecules were quantitated in 16 commercially available immunoglobulin (Ig) preparations by enzyme-linked immunosorbent assays. Whereas three Ig preparations contained no detectable sHLA-ABC, all preparations showed concomitant sHLA-RQP molecules. There was a considerable variability with regard to the individual sHLA concentrations. For sHLA-RQP the values exceeded that found in human plasma of healthy individuals, suggesting that the extraction procedure may concentrate not only Ig, but also HLA class II molecules. Based on the total dosage of intravenously administered immunoglobulins (i.v.Ig), contaminating sHLA molecules may become immunogenic. Furthermore, sHLA molecules are discussed in terms of participation in the well-known immunomodulating effects of i.v.Ig therapy.

A simplified enzyme linked immunosorbent assay utilizing an HLA class I framework-specific monoclonal antibody and a polyclonal enzyme linked beta-2 microglobulin specific antiserum has been established for the quantitative measurement of soluble HLA class I molecules. A total of 219 unrelated healthy individuals and 137 members of 28 families typed for HLA were analyzed for their non-membrane bound, i.e. soluble HLA-A,B,C antigens (sHLA-A,B,C). As reported by others, we observed associations of higher or lower sHLA-A,B,C values to particular HLA antigens: High plasma values were observed in probands positive for HLA-A23, A24, A29, Aw33, Bw65, and Cw8 and low values in HLA-B27 and B37 positive individuals. However, as shown by family studies, levels of sHLA-A,B,C were apparently not controlled by the MHC haplotypes alone, since no significant difference between HLA identical siblings and two haplotype different individuals could be detected. Thus, additional non-MHC linked gene(s) may be involved in the release of class I gene products.