Differential expression of porcine major histocompatibility DNA sequences introduced into mouse L cells

Nucleotide sequence and northern analysis of a bovine major histocompatibility class II DR beta-like cDNA

A 1.2-kb bovine DR beta-like cDNA clone (BoLA-DRB3) was isolated from a peripheral blood lymphocyte cDNA library utilizing a human DR beta cDNA as a probe. BoLA-DRB3 was found to have a high degree of nucleotide sequence similarity (96.8%) with a previously sequenced bovine DR beta-like gene (A1). It is believed that BoLA-DRB3 and A1 represent distinct alleles of one of the three bovine DR beta-like loci. Sequence comparison of BoLA-DRB3 with genes representing the other two bovine DR beta-like loci resulted in moderate degrees of sequence similarities (83.1% and 86.3%, respectively). Comparison of the relative abundance of RNA transcripts of the three bovine DR beta-like loci by Northern analysis of lymphocyte RNA indicated that BoLA-DRB3 is the most actively transcribed of the three bovine DR beta-like genes. Based on these results we suggest that of the three DR beta-like loci thus far identified in the bovine, only one is actively transcribed.

Expression of a class I MHC transgene: effects of in vivo alpha/beta-interferon treatment

Transgenic mice containing a swine class I major histocompatibility complex (MHC) gene, PD1, express swine MHC (SLA) antigen. The tissue distribution of PD1 RNA parallels that observed in the swine, indicating that the expression of PD1 is regulated and that trans-acting factors involved in this regulation have been conserved between the species. Although PD1 RNA levels were much greater in transgenic spleen than in thymus, no difference in the chromatin organization of the PD1 gene was detected. In both tissues, a single DNase I hypersensitive site mapped within the 5' flanking region. In vivo treatment of the transgenics with mouse alpha, beta-interferon increases PD1 expression in a number of tissues. In the spleen, this increase parallels that observed for the endogenous transplantation antigen, Kb, but differs markedly from the differentiation antigen, Qa-2. Increases in cell surface expression of both PD1 and Kb occurred equally in splenic T- and B-cell populations following alpha, beta-interferon treatment. In contrast, Qa-2 expression in B cells was enhanced by alpha, beta-interferon, whereas it was unaffected in T cells and thymocytes.

DNA polymorphism of the HLA-B35 gene associated to different HLA-C locus alleles

Peripheral blood leukocyte DNA from 31 donors, previously typed as HLA-B35, was digested with EcoRV and analyzed by Southern transfer and hybridization to an HLA class I probe. Out of 31 HLA-B35 positive (+) individuals, 24 showed a 4.6-kb band, previously associated with the B35 allele by Cohen et al. (Proc Natl Acad Sci USA 80:6289-6292). The HLA-B35 allele has a strong linkage disequilibrium (70%) with the Cw4 allele. All samples having the 4.6-kb band corresponded to HLA-B35+, Cw4+ cells, whereas those lacking the band came from HLA-B35+, Cw4-negative (-) cells. Five HLA-B35-, Cw4+ samples were also studied and none showed the band. An HLA-B locus-specific probe gave a strong hybridization signal to this fragment, whereas an HLA-C locus-specific probe revealed different bands. The results suggest that the 4.6-kb fragment contains the B35 gene. Digestion with other restriction enzymes, located the polymorphic site to the 3' end of the gene. Analysis of 18 additional individuals with other specificities of the "4c" antigenic cluster (HLA-B18, B51, B52 and B53) showed that the EcoRV/4.6 kb-band was also present in 5/5 B52 cells and 4/4 B53 samples.

Structure and expression of class I MHC genes in the miniature swine

The genome of the miniature swine, unlike other species, contains a relatively small class I MHC gene family, consisting of only seven members. This provides an excellent system in which to identify and characterize the regulatory mechanisms which operate to both coordinately and differentially regulate the expression of a multi-gene family. The structure of class I SLA genes, like other class I genes, consists of eight exons encoding a leader sequence, three extracytoplasmic domains, a transmembrane domain and intracytoplasmic domains. Despite the common structure, two sub-families of class I genes can be distinguished within the SLA family. One, containing the closely related PD1 and PD14 genes, encodes the classical transplantation antigens. Another contains the highly divergent PD6; the functions of the products of this subfamily, if any, are not known. The class I SLA genes share some common regulatory mechanisms, as evidenced by the fact that all three genes analyzed are transcribed in mouse L cells. Furthermore, interferon treatment of transfected mouse L cells enhances expression of all three genes. Both PD1 and PD6 are transcribed in vivo, where the highest levels of expression are observed in lymphoid tissues. Superimposed on the common patterns of class I gene expression are distinct ones, as evidenced by the findings that PD1 is preferentially expressed in B cells, whereas PD6 is preferentially expressed in T cells. These differences may reflect the extensive divergence of the 5' flanking sequences of these genes. Future studies will be aimed at elucidating the precise molecular interactions and mechanisms which give rise to the observed differential expression.

Anti-idiotype to monoclonal anti-swine SLA antibody detects a common idiotype shared by mouse anti-SLA sera and elicits an anti-SLA activity

Heterologous anti-idiotypic reagents have been prepared against a BALB/c anti-swine MHC (SLAd) monoclonal antibody (74-11-10) in order to test for possible interspecies idiotypic cross-reactions of anti-MHC antibodies. Using these reagents to examine xenoantisera produced in BALB/c mice immunized with swine SLAdd peripheral blood lymphocytes, all animals tested were found to express detectable levels of the 74-11-10 idiotype (Id). The Id could also be detected in one out of five BALB/c mice immunized with swine SLAcc PBL. Swine anti-SLAdd alloantibodies were also tested, but failed to show detectable levels of the 74-11-10 Id. The in vivo administration of anti-idiotypic reagents to BALB/c mice induced detectable levels of 74-11-10 Id positive antibodies that bound specifically to SLAdd PBL. Similar treatment of SLAgg swine (recombinant swine expressing the class I MHC molecules of c) with anti-idiotypic antibodies failed to induce anti-SLAd antibody activity. These results thus indicate that 74-11-10 represents a shared idiotype of BALB/c anti-SLAdd antibodies. The presence of 74-11-10 Id in one mouse immunized with SLAcc PBL suggests that the failure of pigs to express the 74-11-10 Id following treatment with anti-idiotypic antibodies may be the result of tolerance rather than absence of the relevant variable region gene(s).