Soluble HLA-DR levels in the maternal circulation of normal and pathologic pregnancy

OBJECTIVE

The purpose of this study was to determine that circulating HLA-DR molecules are important candidates for the monitoring of maternal immunostimulation and immunosuppression.

STUDY DESIGN

Concentrations of soluble HLA-DR molecules were estimated in EDTA plasma samples of 61 nonpregnant women, 123 healthy pregnant women in the second trimester, 66 healthy women who were delivered at term, and 136 women who were delivered because of complications such as uncontrollable preterm intrauterine activation, abruptio placentae, intrauterine growth retardation, preeclampsia, and HELLP (hemolysis, elevated liver enzymes, low platelet count) syndrome.

RESULTS

In comparison to nonpregnant women, the normal course of pregnancy was associated with strongly increasing levels of soluble HLA-DR from second trimester on until term. In comparison to women who were delivered preterm because of uncontrollable intrauterine activation, increased soluble HLA-DR concentrations were detected in case of HELLP syndrome (P <.05), although decreased levels were detected in the case of intrauterine growth retardation, preeclampsia (P <.01), and abruptio placentae (P <.01).

CONCLUSION

Dysregulation of the maternal immune response to pregnancy may play an important role in the cause of complicated pregnancies.

Soluble HLA-DR antigen levels in serum correlate with rheumatoid arthritis disease activity and the presence of disease-associated epitopes

We investigated correlations between soluble HLA-DR (sHLA-DR) molecules and several clinical, biological and genetic parameters associated with rheumatoid arthritis (RA) disease activity. Serum sHLA-DR concentrations were determined in 146 samples from 89 RA patients by an ELISA format, using an antibody combination of mouse and rat monoclonal anti-human HLA-DR antibodies. The mean sHLA-DR serum level in RA patients was significantly increased with 277+/-19 ng/ml compared to 142+/-13 ng/ml of 80 healthy controls (P<0.001). In ascending order of significance, correlations were found between serum sHLA-DR and EULAR swelling and pain scores, Waaler-Rose, RA factor, ESR and CRP (P=0.025 to P<0.001). High sHLA-DR levels were defined above 374 ng/ml that was the 95% confidence interval of the controls. Thirty-seven blood samples (25%) in 31 RA patients were above this level. The EULAR pain and swelling scores, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and RA factor were higher (P=0.044 to P<0.001) at the moment of high sHLA-DR concentrations, compared to the lower concentrations. Higher disease activity was further found in groups of RA patients respectively heterozygous or homozygous for the disease-associated epitope (Q)R/KRAA within the HLA-DRB1 chain, compared to the group without this epitope (P<0.017 for part of the results). Likewise, sHLA-DR was respectively 169+/-17 (no disease associated epitope), 324+/-34 (heterozygous) and 442+/-69 ng/ml (homozygous for the disease-associated epitope on HLA-DRB1 alleles) (P<0.017). In conclusion, this study shows significant correlations between serum sHLA-DR levels and RA disease activity parameters, as well as increased sHLA-DR in patients with disease-associated epitope on HLA-DRB1 alleles.