Immune regulation

HLA-G expression in early embryos is a fundamental prerequisite for the obtainment of pregnancy. Fuzzi, B. et al. Eur. J. Immunol. 32, 311–315 (2002) [ PubMed ]

Release of the non-classical MHC class I molecule HLA-G by cytotrophoblast cells is thought to have a role in the induction of tolerance to paternal antigens of the fetus. Here, the presence of soluble HLA-G molecules in the culture supernatant of early embryos was assessed. Only the embryos that produced soluble HLA-G were successfully implanted, indicating that HLA-G is essential, but not sufficient, for pregnancy.

Vaccines

Autologous dendritic cells transfected with prostate-specific antigen RNA stimulate CTL responses against metastatic prostate tumors. Heiser, A. et al. J. Clin. Invest. 109, 409–417 (2002) [ PubMed ]

Dendritic cells (DCs) are a major focus for immunotherapy at present. This study shows that DCs transfected with mRNA for prostate-specific (self-) antigen (PSA) hold promise for the treatment of metastatic prostate cancer. Transfected DCs induced PSA-specific cytotoxic T-cell responses, with no detectable adverse effects, validating the rationale for further development of this vaccine.

T-cell development

Characterization of T-cell differentiation in the murine gut. Lambolez, F. et al. J. Exp. Med. 195, 437–449 (2002) [ PubMed ]

The stages that thymocytes pass through during development into mature T cells in the thymus are well defined. The sequence of T-cell development in the gut was, until now, unknown. Here, Rocha and colleagues identify and characterize six phenotypically distinct lineage-negative populations in the cryopatch and gut epithelium, and establish a sequence of T-cell precursor differentiation in the gut. Numerous differences between this differentiation process when compared with T-cell development in the thymus are discussed.

Immunosuppression

Neisserial binding to CEACAM1 arrests the activation and proliferation of CD4+ T lymphocytes. Boulton, I. C. et al. Nature Immunol. 3, 229–236 (2002) [ PubMed ]

Although infection with Neisseria gonorrhoeae triggers an intense inflammatory response, the specific immune response to this pathogen is limited, indicating that the gonococci have an immunosuppressive effect on the immune system. This study identifies a mechanism for this immunosuppression, showing that N. gonorrhoeae opacity-associated (Opa) proteins can bind to CEACAM1 (an Ig superfamily member) that is expressed on the surface of CD4+ lymphocytes, and then suppress their activation and proliferation.