Control of rat natural killer cell-mediated allorecognition by a major histocompatibility complex region encoding nonclassical class I antigens.

Abstract

The ability of natural killer (NK) cells to eliminate normal allogeneic hemic cells is well established in several species including mice, rats, and humans. The controlling elements for NK susceptibility in these species map to the major histocompatibility complex (MHC), but in contrast to findings in mice and humans, the mode of inheritance is not always recessive in rats. This finding is not easily explained by the missing self and hemopoietic histocompatibility (Hh) models for NK recognition, and has led to the idea that certain aUoantigens may trigger NK cell reactivity. In our in vitro system for assessing rat NK alloreactivity, we have employed target and inhibitor cells from a large panel ofMHC congenic, intra-MHC recombinant and MHC mutant rat strains, as well as appropriate F1 hybrids between them, and we show the following: (a) The nonclassical class I (RT/.C) region was most important in determining the susceptibility of target cells to alloreactive NK cells in vitro. Lymphocyte susceptibility to lysis in vivo also mapped to the C region, which supports the concept that the in vivo and in vitro alloreactivity assays reflect the same recognition process. (b) Four different RT/-controlled NK allospecificities (represented by the u, l, a, and n haplotypes) could be discerned when we used polyclonal NK cells from the PVG (RTI') strain as effector cells. Three of the target specificities recognized were controlled mainly by the RT1.C region. (c) The expression of RT1.C region-controlled parental strain NK allodeterminants could be demonstrated in F1 hybrids heterozygous for the C region alone and were therefore inherited nonrecessively. (d) Loss of an RTI.C region-controlled NK allospecificity could be shown with the MHC mutant LEW.1LM1 rat strain characterized by a genomic deletion of about 100 kb of the C region. Taken together, these observations have demonstrated a major importance of the nonclassical class I region, i.e., RT1.C, in controlling rat NK allorecognition, and have thereby assigned a hitherto undescribed immunological property to this region. Furthermore, some of the present data are consistent with the existence of polymorphic NKtriggering alloantigens that are coded for by the RT1.C region.

Ly-49s3 Is a Promiscuous Activating Rat NK Cell Receptor for Nonclassical MHC Class I-Encoded Target Ligands

“…In contrast, ALC studies in rats provided ample evidence for stimulatory NK allorecognition both in vivo and in vitro (8,9), and suggested that rat NK cells express a more potent array of activating receptors directed against several distinct target cell allo-MHC determinants encoded within the nonclassical class Ib RT1-C/E/M region (5,10,18,19). We speculated that, like MHC-binding NK receptors in mice and in humans, these rat NK receptors might be functionally associated with DAP12.…”

Two major groups of rat NKR‐P1 receptors can be distinguished based on chromosomal localization, phylogenetic analysis and Clr ligand binding

“…The generation of Con A lymphoblasts and 4-h 51 Cr-release assay was performed as described previously [36]. Three micrograms/well of the indicated purified mAb was added to plated effector cells 20-30 min prior to the addition of target cells.…”

Functional characterization of a conserved pair of NKR‐P1 receptors expressed by NK cells and T lymphocytes in liver and gut

“…Cell purity of NKR-P1G + cells used for experiments were 70-95% NKR-P1G + NKR-P1A + NKR-P1F + CD3 − . The effector cells were used in a standard 4 h 51 Cr-based cytotoxic assay as previously described [42]. Target cells were either stably transfected CHO cells expressing Clr2, Clr4, or Clr7 (CHO WT as control) [16], or 293T cells transiently transfected with Clr cDNA inserted in a pBK-CMV expression vector (Stratagene) with EYFP (Invitrogen) inserted into the reading frame, using FuGENE R 6 (Roche) (manufacturer's protocol) (control is transfected with pBK-CMV.EYFP without Clr insertion).…”