Detection of HLA-G by a specific sandwich ELISA using monoclonal antibodies G233 and 56B.

Human leukocyte antigen (HLA)-G, which is mainly expressed at the maternal-fetal interface, may play a role in the immune tolerance of the semi-allogenic fetus by the mother. Functional studies have shown that HLA-G is indeed a potential modulator of different immune responses. Therefore, it is of interest to study the level of expression of soluble HLA-G in several biological fluids derived from women with and without fertility problems. In order to measure soluble HLA-G, a reliable and sensitive HLA-G specific sandwich ELISA is required. Here, we describe such an ELISA in which G233 is used as the coating antibody and 56B as the detecting antibody. In comparison with two other assays, this assay shows highest responses to recombinant HLA-G and native HLA-G in primary trophoblast culture supernatant and high responses to HLA-G in amniotic fluid. No HLA-G in follicular fluid or preimplantation embryo culture supernatant could be detected.

Peripheral natural killer cytotoxicity and CD56(pos)CD16(pos) cells increase during early pregnancy in women with a history of recurrent spontaneous abortion.

For diagnostic purposes we assessed peripheral natural killer (NK) cell cytotoxicity and NK and T cell numbers to assess their putative predictive value in recurrent spontaneous abortion (RSA). A total of 43 women with subsequent pregnancy, 37 healthy controls and 39 women successfully partaking in an in-vitro fertilization (IVF) procedure, were included in the study. We show that before pregnancy, levels of NK cytotoxicity and numbers of both single CD56(pos) and double CD56(pos)CD16(pos) cells were similar between RSA women and controls. But notably, within the RSA group, NK cell numbers of <12% were strongly associated with a subsequent pregnancy carried to term. Supplementation of folic acid led to an increase of single CD56(pos) cells, but cytotoxic function appeared unaffected. The expression pattern of killer inhibitory receptors on CD56(pos) cells was not different between patients and controls. A longitudinal study revealed that, compared with controls, in RSA women higher numbers of double CD56(pos)CD16(pos) cells were present during early pregnancy, paralleled by an increase in cytotoxic NK cell reactivity. The single CD56(pos) population decreased in number. In conclusion, the analysis of peripheral NK cell characteristics appears a suitable diagnostic tool in RSA. Immunomodulation aimed at NK cell function appears a promising therapeutic measure.