Antiquités d'Herculanum [Texto impreso]

En port. de la parte de texto consta año 1780

Antiquités d'Herculanum [Texto impreso]

En port. de la parte de texto consta año 1780

Antiquités d'Herculanum [Texto impreso]

Contiene: Tome I Bronces

Antiquités d'Herculanum [Texto impreso]

Port. independiente para la parte de texto fechada en 1780

Antiquités d'Herculanum [Texto impreso]

Contiene: Tome II Bronces

Antiquités d'Herculanum [Texto impreso]

Port. independiente para la parte de texto fechada en 1780

Antiquités d'Herculanum [Texto impreso]

En port. de la parte de texto consta año 1789

Antiquités d'Herculanum [Texto impreso]

Port. independientes para la parte de texto fechada en 1797

Antiquités d'Hercul[anum] [Texto impreso]

En port. de la parte de texto consta año 1780

Antiquités d'Herculamun [Texto impreso]

Port. independiente para la parte de texto fechada en 1780

Direct evidence to support the role of HLA-G in protecting the fetus from maternal uterine natural killer cytolysis

HLA-G is a nonclassical major histocompatibility complex class I molecule selectively expressed on cytotrophoblasts at the feto–maternal interface, where it may play an important role in maternal tolerance of the fetus. We provide direct evidence under physiological conditions that supports the role of HLA-G in protecting cytotrophoblasts against natural killer (NK) cytolysis in 6 semiallogenic combinations of maternal uterine NK cells and their own trophoblast counterparts, as well as in 20 allogenic combinations of maternal uterine NK cells and trophoblasts from different mothers. We show that, in all cases studied, this HLA-G-mediated protection was abolished by treatment of cytotrophoblasts with an HLA-G-specific mAb. The HLA class I-negative K562 cell line transfected with the predominant HLA-G1 isoform results in similar protection and abolition from maternal uterine NK lysis. Because maternal uterine NK cells express killer inhibitory receptors for HLA-G, we conclude that their interactions contribute to the survival of the fetal semiallograft by confering immunological tolerance to its tissues.

The α1 domain of HLA-G1 and HLA-G2 inhibits cytotoxicity induced by natural killer cells: Is HLA-G the public ligand for natural killer cell inhibitory receptors?

We have investigated the protective role of the membrane-bound HLA-G1 and HLA-G2 isoforms against natural killer (NK) cell cytotoxicity. For this purpose, HLA-G1 and HLA-G2 cDNAs were transfected into the HLA class I-negative human K562 cell line, a known reference target for NK lysis. The HLA-G1 protein, encoded by a full-length mRNA, presents a structure similar to that of classical HLA class I antigens. The HLA-G2 protein, deduced from an alternatively spliced transcript, consists of the α1 domain linked to the α3 domain. In this study we demonstrate that (i) HLA-G2 is present at the cell surface as a truncated class I molecule associated with β2-microglobulin; (ii) NK cytolysis, observed in peripheral blood mononuclear cells and in polyclonal CD3− CD16+ CD56+ NK cells obtained from 20 donors, is inhibited by both HLA-G1 and HLA-G2; this HLA-G-mediated inhibition is reversed by blocking HLA-G with a specific mAb; this led us to the conjecture that HLA-G is the public ligand for NK inhibitory receptors (NKIR) present in all individuals; (iii) the α1 domain common to HLA-G1 and HLA-G2 could mediate this protection from NK lysis; and (iv) when transfected into the K562 cell line, both HLA-G1 and HLA-G2 abolish lysis by the T cell leukemia NK-like YT2C2 clone due to interaction between the HLA-G isoform on the target cell surface and a membrane receptor on YT2C2. Because NKIR1 and NKIR2, known to interact with HLA-G, were undetectable on YT2C2, we conclude that a yet-unknown specific receptor for HLA-G1 and HLA-G2 is present on these cells.