A new locus (H-2T) at theD end of theH-2 complex

A.TH (H-2 ^t2) anti-A.TL (H-2 ^t1) effectors, obtained after in vitro restimulation of in vivo sensitized cells, react in the CML assay not only withH-2 ^t1, but also with a number of other targets carrying unrelatedH-2 haplotypes. The broad cross-reactivity can be explained by postulating the presence among the effectors of at least two populations of cells, one reacting with antigens controlled by theI region, and the other directed against antigens controlled by a locus at theD end, outside theH-2 complex. The existence of the two cell populations is also supported by cold-target inhibition data. The locus coding for the D-end CML antigens maps betweenQa-2 andTla. The locus is assigned the symbolH-2T. TheH-2T-locus CML is seen only after in vivo presensitization, but the killing is not K/D-restricted.     

Antigen-specific helper T cells recognize determinants encoded in the H-2D region of the H-2 gene complex

Observations have frequently been interpreted as showing that the helper T cells which collaborate with alloantigen-specific cytotoxic T-cell precursors can only recognize antigens encoded in the I region of the H-2 gene complex. An experimental system is described here that allows analysis of the recognition repertoire of these helper cells. CBA helper T-cell precursors can be primed in vitro to antigens encoded in the H-2 ^b gene complex. These helpers can then be tested for the existence of a subset of helper cells which recognize antigens encoded in the D region of H-2 ^b haplotype. CBA thymocytes were used as a source of cytotoxic T-cell precursors that respond poorly in the absence of exogeneous helper activity. The source of alloantigen was varied by using irradiated spleen cells from various (BALB/c × recombinant)F₁ hybrid mice as stimulator cells. When the stimulator cell bears BALB/c determinants recognized by the cytotoxic T-cell precursor and also bears only the D region antigens of the H-2 ^b haplotype, an anti-BALB/c cytotoxic response is generated only if the anti-H-2^b helper population contains cells able to recognize H-2D^b. A positive cytotoxic response was obtained, indicating that helper cells are not limited to recognition of I region antigens and can efficiently recognize antigens encoded in the D region of the H-2 gene complex. This was confirmed by the demonstration of helpers specific for H-2D^d. We were unable to detect any evidence for Ia-restricted recognition of the H-2D alloantigens, suggesting that, as for cytotoxic T lymphocytes (CTL), helper cell recognition of class I alloantigens is an unrestricted event.     

H-2U: A new region at the D end of the murine MHC

A new genetic region, mapping within the H-2 complex, has been serologically defined with several alloantisera raised in mice which differ at the D region. When these antisera were absorbed to remove H-2D antibodies, residual antibody activity remained that reacted in a strain-specific manner, and the antigens involved mapped to a new genetic region between the S and D regions. Two allelic variants relating to the d and k haplotypes have been defined by genetic mapping studies. This new region has been designated H-2U and the antigens it controls appear to resemble Ia antigens in their cellular distribution and molecular weight. The new antigen is primarily expressed on B cells, and is carried on protein molecules having approximate molecular weights of 36 000 and 60 000 daltons and resembling the and - chain dimer characteristic of Ia antigens.     

A histocompatibility region (H-2IC) in theIC region of theH-2 complex of the mouse

Skin graft rejection in congenic pairs of mice differing only at theH-2 complex appears to be influenced by at least 3 genes (H-2K, H-2D, H-2I); we now describe a fourth,H- 2IC: Grafts transplanted across anIC difference are sometimes rejected. TheI-C regions of three differentH-2 haplotypes (d,k,s) were studied in different combinations, and variable patterns emerged: (a)IC ^d : B10.S(7R) show delayed or no rejection of first B10.S(9R) grafts, but grafts to immunized recipients were usually rejected in 20 days; (b)IC ^k : in two combinations (A.AL A and B10.HTT B10.S[9R]) first grafts were rejected by day 30, although grafts to immunized mice showed a different pattern. In the third combination (B10.HTTB10.S[7R]) first grafts were retained but immunized mice rejected their grafts, (c)IC ^s : B10.S(9R) regularly reject B10.S(7R) first grafts, but immunized mice retain their grafts. In two other combinations first grafts were retained but grafts to immunized recipients were rejected; while in a third combination rejection did not occur at all. The background of the recipient appeared to be important in determining the variable pattern of rejection, and there is evidence for a similarity of the H-genes inIC ^s andIC ^k , and inIC ^k andIC ^p . Graft rejection occurred independently of known differences in Ia specificities, indicating thatH-2IC and the genes determining Ia specificities are probably different, although when grafts were performed in the presence of known la differences, graft rejection usually occurred.     

PFGE mapping and RFLP analysis of the S/D region of the mouse H-2 complex

We have constructed a long range restriction map of the S/D segment of the mouse H-2 complex by pulsed field gel electrophoresis and hybridization with mouse cDNA probes to Bf and Tnfa genes and human cDNA probes to BAT2, BAT3, BAT4, BAT5, and BAT6 genes which have recently been mapped to the human HLA complex between C2 and HLA-B. The distance between the mouse C2 and Tnfa genes was found to be approximately 350 kilobases. The position of the mouse Bat genes in this map were found to be comparable to the position of the BAT genes in the human HLA complex. A panel of recombinant mouse strains was also examined by restriction fragment analysis with probes detecting the Hsp70, Bat5, and Tnfa genes. The results indicate that recombination in this segment is not random. No recombinants were found with crossovers between the C2 and Hsp70 genes and only one recombinant was found with a crossover between Tnfa and H-2D. In contrast, the crossover sites of 16 recombinants were mapped between the Hsp70 and Tnfa genes. Seven of these recombinants were found to have crossovers between Hsp70 and Bat5 and three recombinants were found to have crossover sites between Bat5 and Tnfa.Address correspondence and offprint requests to: W. Lafuse.     

Interaction of H-2Db with mutant histocompatibility gene H (KH-11) in the mouse

The detectable presence of H (KH-11)b, a mutant non-H-2 histocompatibility gene, was previously shown to depend upon the simultaneous presence, in the skin-graft donor, of both the mutant gene and the H-2b haplotype. The experiments reported here demonstrate that H-2Db is the essential element of H-2b for this interaction. Of two H-2Db histocompatibility mutations, H-2bm13 can replace H-2Db in this interaction, but H-2bm14 cannot.     

Bone marrow cell transplants involving intra-H-2 recombinant inbred mouse strains. Evidence that hemopoietic histocompatibility-1 (Hh-1) genes are distinct from H-2D or H-2L

Hemopoietic histocompatibility (Hh) Ag are noncodominantly expressed on bone marrow stem cells and other normal and neoplastic cells of hemopoietic origin. H-2/Hh-1 allogeneic or parental-strain bone marrow grafts are eliminated in a determinant specific manner by NK cells. In inbred mouse strains, seven Hh-1 alleles representing combinations of five different Hh-1 antigenic determinants are described. Each Hh-1 allele maps in the vicinity of H-2D, and the genes that map to Hh-1 are transacting regulatory genes. The expression of a particular determinant depends on the absence of the regulatory gene and the presence of the appropriate structural gene. The primary focus of this study is to ascertain whether the Hh-1 phenotype and the serologic H-2DL typing are always correlated or whether recombinant can separate the two. To achieve this, we used a panel of irradiated hosts that are able to recognize the different Hh-1 determinants on the bone marrow cells of congenic intra-H-2 recombinant donors. We report: 1) the majority of strains show a correlation between Hh-1 and H-2DL: 2) B10.RQDB and B10.WB strains dissociate Hh-1 from Lb: 3) nine H-2S/D interval recombinant strains exhibit no correlation between the H-2DL type and Hh-1 phenotype; and 4) in two strains from this group, B10.D2 (R106) and B10.RSF5, H-2S/D crossovers occurred within Hh-1r, (Hh-1 regulatory). We conclude that Hh-1r is a distinct regulatory locus mapping telomeric of H-2S and centromeric of, although probably closer to, H-2D.     

Localization of the L1Md family of repeated sequences in the mouse albumin-alpha-fetoprotein gene complex.

Studies on the beta-globin gene complex in the mouse have demonstrated the existence of repeated DNA sequences interspersed throughout the intergenic regions (1,2). These sequences are members of families of middle repetitive sequences and have been mapped to specific intergenic sites in the 60 kbp beta-globin complex. In this study we present evidence that members of this middle repetitive family of DNA sequences, the L1Md family, are interspersed throughout the mouse albumin and alpha-fetoprotein gene complex. Unlike those of the beta-globin complex, all of which are found in the intergenic regions, these sequences are localized within intron 12 of the albumin gene and intron 3 of the AFP gene as well as twice in the 13.5 kbp intergenic region that links the albumin gene to the AFP gene.     

Localization of H-2Kk in developing mouse teeth using monoclonal antibody

The in situ distribution of H-2 antigens during mouse tooth morphogenesis was investigated using monoclonal antibodies to H-2Kk and indirect immunofluorescent techniques. H-2 antigens were detected in the basement membrane region of fetal molars; they were absent from both the epithelial and dental mesenchyme. H-2 antigens were not found in newborn and 4-day-old mouse molars.     

Cloning and identification of the H-2D p gene

We have cloned six different class I genes from a B10.P sperm library. After cotransfection with the herpes simplex tk gene, one L-cell line was found to react with six H-2D^p-specific monoclonal antibodies. The cell line L12a did not react with K^p-specific monoclonal antibodies. This identification was confirmed by mapping a 2.5 kb Bam H 1 restriction fragment present in the 12a DNA clone to the D-TL region of H-2 ^p. Only a single 8.8 kb Barn H1 fragment can be assigned to K ^p by restriction fragment length polymorphism, while many others map to the D-TL interval. A restriction map of 12a is presented.