Jack H. Stimpfling

Genetic nomenclature for the H-2 complex of the mouse

The H-2 complex (system, Snell and Stimpfling 1966) represents a segment of chromosome 17 delimited by the H-2K and H-2D loci (Table 1). The complex is split by the Ss locus into two ends, the K end between H-2K and Ss, and the D end between Ss and H-2D. The term end can also be used to indicate the direction; thus the K end could mean the direction from the Ss locus toward the centromere, and the D end the direction from the Ss locus toward the telomere. The H-2 complex is composed of regions, subregions and loci. An H-2 region is a segment of the H-2 complex delimited by recombination and consisting of a marker gene and an undeterminate number of neighboring loci. The H-2 complex is to be divided into four regions, K, /, S and D, defined by marker genes H-2K, Ir-lA, Ss and H-2D, respectively. Subregions of a given region are segments identified by distinct but functionally related marker genes and separated from each other and the other regions by recombination. The I region is to be divided into two subregions, Ir-lA and Ir-lB, formerly termed Ir-1 and Ir-IgG, respectively. It is assumed that each region or subregion contains at least one locus,

Identification of Specificity H-2.7 as an Erythrocyte Antigen : Control by an Independent Locus, H-2G, between the S and D Regions

SpecificityH-2.7 is expressed predominantly on erythrocytes and controlled by a gene that maps within theH-2 gene complex at a locus, designated asH-2G, which apparently lies between regionsS andD. Three phenotypes have been observed with respect to this antigen: a) positive by direct test and absorption (haplotypesH-2f,H-2j,H-2p,H-2s); b) positive only by absorption (H-2k); and c) negative (H-2b,H-2d,H-2q). New crossover positions have been established for severalH-2 recombinants based on classifications for theH-2G locus.

Monoclonal antibodies defining mouse tissue antigens encoded by the H-2 region.

A number of mouse hybridomas which secrete monoclonal antibodies (mAb) have been produced in this laboratory, mainly for the purposes of recognizing and studying crossover events within the H-2 complex of recombinant mice. The cross-reaction patterns for these mAb were determined by cytotoxicity tests against a panel of mouse strains carrying H-2 haplotypes a, b, d, f, k, n, p, q, r, s, u, and v, up to fifty-five recombinant H-2 haplotypes, and several H-2 mutant haplotypes. The test results were compared with the latest listing of H-2 haplotypes and genes (Klein et al. 1983) to determine specificity. Numerical specificities are generally not given since B10.W strains were not tested and because many of the specificities are new. The hybridomas were established as described by Ozato and co-workers (1980), with the following modifications: the myeloma line P3X63,Ag8.653 was used as the fusion partner except where noted; RPMI 1640 with 15 % fetal bovine serum, 0.01 mM beta mercaptoethanol and 100 mg/1 garamyacin was used as tissue culture medium; thymocytes were added as feeder cells and fusion procedures were carried out at room temperature. Primary immunizations were by skin grafting and after 3 weeks, the

Periodic variations of the hemagglutinin response in mice following immunization against sheep red blood cells and alloantigens.

The hemagglutinin response in mice was closely followed for varying periods of time after a single injection of allogenic thymus cells and sheep red blood cells (SRBC). Time-response curves were obtained for four experimental situations in which the recipients received (1) SRBC, (2) thymus cells, (3) SRBC plus thymus cells administered simultaneously, and (4) SRBC administered 6 days after the injection of thymus cells. Hemagglutinating antibody against SRBC and mouse red blood cells persisted for several weeks after immunization. The time-response curves constructed after immunization against either SRBC or thymus cells included fluctuations which exhibited a more or less regular cycle. After the simultaneous administration of SRBC plus thymus cells, the fluctuations in the time-response curves waxed and waned in unison for several weeks. When SRBC were administered 6 days after immunization with thymus cells, the response curves against both SRBC and mouse red blood cells displayed fluctuations, but not in synchrony.

Evidence that the "R: and "Z: blood group specificities of mice are allelic and distinct from H-2.

New data are presented concerning a blood group locus of mice originally identified by Hoecker and co-workers. Specificity “R”, best defined by a (BIO X LP.RIII) anti-RIII, and specificity “Z”, best defined by an RF anti-C3H, are shown to be antithetical. Specificity R is present in strains RF, RIII, and F, absent from all other strains tested; specificity Z is absent from RF, RIII and probably F, and present in all other strains tested. Tests in a segregating generation show that R and Z are determined by alleles at a single locus. The locus is distinct from and probably not linked with H-2, though distorted ratios have been observed in certain cases. Evidence with respect to distinctness from other histocompatibility and blood group loci is incomplete, though there is a considerable presumption that it is not the same as any of the 10 loci identified by strictly histogenetic methods. Strong anti-R sera are easily prepared; specificity Z is somewhat weaker.

Meiotic recombination within the H-2K-H-2D interval: characterization of a panel of congenic mice, including 12 new strains, using DNA markers.

Intra-H-2 recombinant congenic strains are widely used to localize traits to specific subregions of the major histocompatibility complex and have provided evidence for the existence of meiotic recombinational hotspots in mammals. Forty-seven intra-H-2 recombinant strains, including 12 not previously reported, have been identified by serological typing in our laboratory. We have extended the analysis of the cross-over sites in these mice using DNA markers for Ab, Aa, Eb, Ea, Cyp21-ps, D17Tu3, Bat7, and Bat5. The recombinant chromosomes of these congenic strains include loci derived from the a, b, f, k, p, q, r, s, u, and v haplotypes of H-2, providing a diverse panel of strains. Although some alleles of Bat7 could not be distinguished from one another, results from the majority of strains indicated a probable gene order of C4Slp/D17Tu3-Bat7-Bat5-H-2D. No recombinants between Cyp21-ps, C4Slp, and D17Tu3 were observed. The crossover sites in 31 of the 47 intra-H-2 recombinants were within the C4Slp/D17Tu3—H-2D interval; of these 31 crossovers, three were bracketed by D17Tu3 and Bat7, ten by Bat7 and Bat5, seven by Bat5 and H-2D, and 11 by D17Tu3 and Bat5. The results from all 47 strains suggest recombinational hotspots within the C4Slp/D17Tu3—H-2D interval and emphasize the influence that specific haplotypes can have on preferred crossover sites.

Transplantation effects of a unique major histocompatibility complex class I mutation.

&NA; This study describes a novel MHC class I mouse mutant that was discovered because of loss of reactivity of its cells to monoclonal antibodies. The mutation occurred in the H-2K° molecule and is the first in vivo mutation described that has a single altered amino acid residue (amino acid 107) distant from the regions considered to be peptide or TCR contacts. Nevertheless, skin grafts from the mutant to the parent are rejected by CD8+ T-cells. In the reciprocal direction, the mutant shows partial tolerance to parental skin grafts, suggesting that the mutant is inefficient in selecting alloreactive T-cells specific for the wild-type K° molecule.

Identification of private H-2 and Ia specificities of H-2r haplotype

The prototype strain for the H 2 r haplotype is RIII/J, B10.RIII is the congenic H U strain on a C57BL/10 background, and strain designated LP.RIII is also available. The H 2 marker for the H 2 r haplotype was H-2.18 (Snell et al. 1973) and even though it was originally assigned to the D loci, anti-H-2.18 antiserum was made in a combination incompatible in the whole H 2 complex and could contain antibodies directed against both Kand D-gene products as well as against I-, TL-, and Q-region products. A recombinant involving parental haplotypes H 2 t2 [B 10.S(7R) K s I S S S D e] and H 2 ~ was established as a congenic strain on a C57BL/10 background and designated B 10.RIII(20R) (J. H. Stimpfling, unpublished data) with the haplotype symbol H 2 ~wl (with the permission ofP. D6mant, H-2 Nomenclature Committee). B10.RIII(20R) was originally typed as expressing K Sand D~-gene products. We have extended this analysis using a microcytotoxicity assay with a complete panel of anti-H-2 and anti-Ia sera, as shown in Table 2. The H 2 haplotypes of strains used in this study are listed in Table 1. The two antisera used to detect H-2.18, (B6 x A/J)F 1 anti-B10.RIII and [-B 10.A(2R) x C3H.NB]F 1 anti-Bl0.RIII (anti-H-2 r) reacted with B10.RIII (20R). However, the observed cytotoxicity was directed against the Ia.12 specificity, since absorption of both these antisera by B10.S(7R) removed this activity against B10.RIII(20R). Both anti-H-2 r sera appeared to react with Kand Iregion gene products. The H-2.18 designation should thus be used to describe the H-2K r private specificity. Detection of H-2.19 [A.AL x B10.A)F1 anti-A.TL (anti-KS)] and the lack of cross-reacting H-2.25 antigen (K r) confirmed the expression of the KS-gene product in B 10.RIII(20R). The absence of the H-2.4 antigen, the Dd-region private specificity of B10.S(7R), was also confirmed by lack of reaction of B10.RIII(20R) with [B10.AM x C3H.OL]F1 anti-B10.D2 (anti-De; anti-H-2.4). The D region of B10.RIII(20R) was derived from the B10.RIII parental chromosome.

The Ea-2 (H-14) cellular antigen system in the mouse.

Data are presented concerning the relationship of the H-2 gene complex and the Ea-2 gene locus in the mouse genome. The results of independently performed linkage studies are in accord with the conclusion that H-2 and Ea-2 are distinct genetic entities, but opinion differs as to whether the respective genes are on the same or different chromosomes. The data described in this account provide additional support for the view that H-2 and Ea-2 assort independently of each other, at least in the linkage test cross that was studied. Possible reasons for the seemingly discordant results of different investigators are considered. Some peculiarities of the Ea-2 system are described.

Control of the immune response to the ea-2.1 Alloantigen of the mouse by the h-2 complex.

The immunization of selected congenic strains and hybrids with the Ea-2.1 cellular alloantigen of the mouse shows that the anti-Ea-2.1 immune response is regulated by a gene or genes associated with the H-2 gene complex. It was earlier demonstrated that H-2r and H-2b were, respectively, responder and nonresponder haplotypes. In this report it is shown that the haplotypes H-2d and H-2g2 are also responder haplotypes, while H-2a, H-2k, H-2m, H-2v, H-2q, H-2awl and H-2u are nonresponder haplotypes. The responder H-2g2 and nonresponder H-2awl haplotypes are recombinant configurations that map the Ea-2.1 regulator gene, or genes, within or adjacent to the I-A subregion of the H- 2 gene complex.