Quantitation of Soluble HLA Class II Molecules by an Enzyme‐Linked Immunosorbent Assay

摘要

AbstractIn order to quantify soluble HLA‐DR,DQ,DP molecules (sHLA‐RQP) an enzyme‐linked immunosorbent assay was developed utilizing two monoclonal antibodies specific for HLA‐DR,DP (Tü35) and HLA‐DQ (Tü22) gene products, respectively. Highly purified HLA class II molecules isolated from a lymphoblastoid cell line were used for calculation of exact sHLA‐RQP protein values. Circadian variations of sHLA‐RQP plasma levels were studied in 7 healthy probands showing no significant deviations; measurements in 4 probands at intervals between 4 and 6 weeks revealed that sHLA‐RQP levels remain relatively stable. The population analysis of 209 unrelated, HLA‐typed healthy donors resulted in an average protein concentration of 1.53 ± 2.44 μg/ml plasma for sHLA‐RQP. Four out of 209 probands (=1.9) had no detectable sHLA‐RQP. Significant associations of high or low sHLA‐RQP levels to particular HLA‐DR or ‐DQ specificities were not observed. However, plasma derived from HLA‐DR9 positive had the highest and from HLA‐DR8 positive donors the lowest mean sHLA‐RQP values. By comparing HLA identical with two‐haplotype‐different siblings we found no evidence that sHLA‐RQP plasma levels are under genetic control of the HLA complex or closely linked genes. Furthermore, soluble HLA class I plasma concentrations in 100 probands analyzed