The murine MHC class I genes, H-2Dq and H-2Lq, are strikingly homologous to each other, H-2Ld, and two genes reported to encode tumor-specific antigens.

Abstract

Two phenomena appear to distinguish the D region class I genes from those in the K region in the murine MHC: (a) haplotype disparity in the number of expressed D region class I molecules has been observed; and (b) clines of closely related D region class I molecules among and within mice of different H-2 haplotypes can be defined. Both of these observations have been based on serological and peptide mapping analyses of these molecules. Recent reports using molecular biological approaches have corroborated these findings. Since the mouse strain B10.AKM expresses multiple D region class I antigens, all of which are closely related to the prototypic Ld molecule, we investigated the Dq region of B10.AKM using molecular approaches. Three D region class I genes were isolated from genomic B10.AKM bacteriophage and cosmid libraries. Based on alignment of those genes with the BALB/c D region class I genes by analogous restriction endonuclease sites and by hybridization of one of those genes with a D4d gene-derived oligonucleotide probe, we have designated these genes as Dq, Lq, and D4q. As determined by DNA-mediated gene transfer to mouse L cells followed by serological analyses, the Dq and Lq genes encode previously characterized Dq region class I antigens. The nucleic acid sequence comparisons of the Dq and Lq genes demonstrated a higher level of homology with the Ld and Db genes than with other D region class I genes. In addition, CTL stimulated with a Dq, Lq, or Ld gene transfectant showed strong crossreactions with the other transfectants as targets, suggesting that the products of these genes are also functionally related. Thus, these studies suggest that the L molecule represents a prototypic structure shared by several D region gene products, and furthermore, the duplication of an Ld-like progenitor gene resulted in two Dq region class I genes, Dq and Lq. Unexpectedly, the sequences determined for the Dq and Lq genes are nearly identical to the sequences of two genes, A166 and A149, respectively, which were reported to encode the tumor-specific antigens; these novel class I genes were isolated from an H-2k fibrosarcoma, 1591. This raises the distinct possibility that these purported tumor-specific class I genes were introduced into this tumor by contamination.

Polymorphism at Position 97 in MHC Class I Molecules Affects Peptide Specificity, Cell Surface Stability, and Affinity for β2-Microglobulin

“…In contrast, the reciprocal exchange chimeric proteins containing L d residues in the first amino-terminal quarter of the ␣2 (14,19,20), was used in most experiments throughout this report. The use of mAb 28-14-8, which recognizes both empty class I-␤ 2 m heterodimers and peptide-associated class I molecules (12,14,22), eliminates any reagent bias in the above immunoprecipitation studies, since this mAb efficiently immunoprecipitates almost all class I molecules containing the L d ␣3 domain. Nevertheless, mAbs other than mAb 28-14-8, specifically mAbs B22/249, 30-5-7, and 64-3-7, were also used, and when those mAbs were capable of immunoprecipitating these molecules, similar results were obtained as when using mAb 28-14-8 (data not shown).…”

“…The L q transfectant had been generated previously by transfection of DAP-3 with the intact cosmid 33.3 containing the L q gene (14). The L d /L q chimeric molecules were generated using the PCR technique, splicing by overlap extension, developed by Pease and colleagues (30).…”

“…L q is the most similar documented allele of L d and differs from L d by only six amino acid residues in the ␣2 domain (14,15). Despite this similarity, L q is expressed at higher levels on the cell surface (16) and displays an increased affinity for ␤ 2 m (16) and increased cell surface stability compared with L d .…”

Identification and Characterization of the Immunodominant Rat HER-2/neu MHC Class I Epitope Presented by Spontaneous Mammary Tumors from HER-2/neu-Transgenic Mice

“…The same neu-expressing NIH 3T3 cells were transduced with a murine GM-CSF retrovirus using the same methods for inserting the B7-1 gene to create 3T3neuGM vaccine cells. L-D q cells and L-L q cells are murine fibroblast cell lines transfected with murine H-2D q or -L q , respectively (42). All of the above cell lines were maintained at 37°C and 10% CO 2 in DMEM (Life Technologies, Rockville, MD) supplemented with 10% bovine calf serum (HyClone, Logan, UT), 1% L-glutamine (JRH Biosciences, Lenexa, KS), 1% nonessential amino acids (Sigma-Aldrich, St. Louis, MO), 1% sodium pyruvate (Sigma-Aldrich), and 0.5% penicillin/streptomycin (Sigma-Aldrich).…”

Homology Between an Alloantigen and a Self MHC Allele Calibrates the Avidity of the Alloreactive T Cell Repertoire Independent of TCR Affinity

“…We initially sought to determine whether the L dspecific 2C T cell clone can recognize the highly related class I MHC molecule L q . H-2L d and H-2L q are highly homologous class I molecules with 98% identity in amino acid sequence (26). Fig.…”