The contribution of NZW genes to lupus-like disease in (NZB x NZW)F1 mice

A unique sequence of the NZW I-E beta chain and its possible contribution to autoimmunity in the (NZB x NZW)F1 mouse

The (NZB x NZW)F1 mouse strain develops a syndrome of accelerated autoimmunity including severe renal disease and early death. Evidence suggests that class II molecules play a central role in this process. Previous studies have suggested that the NZW strain contributes at least one gene to the development of accelerated autoimmunity that is linked to the H-2 complex, and antibodies to murine class II molecules have been used to ameliorate disease in (NZB x NZW)F1 mice. We therefore wished to sequence the class II molecules from NZW mice to identify any unique sequences that may contribute to disease development. We constructed oligonucleotide primers corresponding to the 5' and 3' regions of the second exon of class II genes from a variety of haplotypes, and used these primers in a polymerase chain reaction to sequence the second exon of the NZW I-A alpha, I-A beta, and I-E beta genes. We report that the second exons of NZW I-A alpha, I-A beta, and I-E alpha are identical to their counterparts of the previously sequenced u haplotype, and that the second exon of NZW I-E beta is identical to its counterpart from u except for a single base change that results in a substitution of arginine for threonine at amino acid 72. This base and amino acid are identical to those found at the same positions in the s haplotype.

Oestradiol suppression of delayed-type hypersensitivity in autoimmune (NZB/NZW)F1 mice is a trait inherited from the healthy NZW parental strain

In this paper we report that treatment with 17 beta-oestradiol depresses cutaneous delayed-type hypersensitivity (DTH) to oxazolone (OXA) in female oophorectomized NZB/W mice. Analysis of the parental strains revealed that this oestrogen-induced inhibition of DTH mice is a trait inherited from the healthy NZW and not from the autoimmune NZB strain. The down-regulating effect of oestradiol on DTH in female NZB/W mice was found both in the sensitization and effector phase of the DTH response. Decreased DTH reactivity to OXA was demonstrated in oophorectomized NZB/W and NZW mice after administration of both low, physiological doses (s.c. injections) and high, pharmacological doses (siliac tube implantation) of oestradiol. In addition, s.c. implantation of testosterone containing siliac tubes suppressed DTH reactivity to OXA in castrated male NZW mice. This down-regulating effect was not found in male NZB or NZB/W mice similarly treated. Serological analysis revealed that high doses of oestradiol increased whereas testosterone depressed the IgG anti-OXA antibody responses in female NZB/W mice. Our results indicate that one possible contribution of the NZW parental strain to the lupus disease in NZB/W mice is a trait of oestrogen sensitivity leading to the acceleration of the autoimmune disease, the latter feature being inherited from NZB mice.

Genetics of experimental lupus nephritis: non-H-2 factors determine susceptibility for renal involvement in murine chronic graft-versus-host disease

Chronic graft-versus-host disease (GvHD) was induced in (C57BL/10 x DBA/2)F1 and (B10.S x DBA/2)F1 hybrids by injection of DBA/2 lymphocytes. All of the animals developed GvHD. Renal disease and proteinuria occurred in all of the (C57BL/10 x DBA/2)F1 hybrids, but only in 54% of the (B10.S x DBA/2)F1. The type of renal lesion was similar in all diseased animals of both strains, i.e., immune complex glomerulonephritis (ICGN) with deposition of antibodies and complement in glomeruli. To find out whether H-2 haplotype or other factors, such as non-H-2 linked genes, determine the susceptibility for renal involvement in GvHD, we produced (B10 x B10.S)F1 x DBA/2 mice, determined their H-2 genotype serologically, and separated them into H-2b/d and H-2s/d groups. These two groups did not differ with respect to susceptibility to renal disease in the course of GvHD, which indicates that H-2 is not the decisive genetic factor. We conclude that factors not linked with H-2 exert a major influence on susceptibility to GvHD-related renal disease in these mice.

Bone marrow cells from young and old New Zealand black mice can reconstitute B lymphocytes in severe combined immunodeficient recipients

The formation of B lymphocytes in young New Zealand Black (NZB) mice proceeds at an accelerated rate, resulting in a deficiency of B lineage progenitors in mice of 15 weeks of age and older. Multiple studies have indicated that intrinsic defects in B lineage cells as well as in the hemopoietic microenvironment in which they develop contribute to these cellular abnormalities. To determine whether the B-cell hyperactivity observed in young mice could be observed in a normal environment, bone marrow cells from young (4 weeks or less) NZB donors were transplanted into Severe Combined Immunodeficient (SCID) mice that have a marked deficiency of lymphocytes but an apparently normal hemopoietic microenvironment. Engraftment of donor lymphoid cells can occur without pretransplant conditioning regimens, thus minimizing the chances of transferring microenvironmental elements. Marrow from young NZB donors reconstituted surface IgM-expressing B cells and CFU-B (B-cell colony-forming unit) in the marrow of SCID mouse recipients to levels comparable to that observed with donor NZB.xid marrow. The latter mice carry the xid gene that ameliorates the defects exhibited by B lineage cells of NZB mice. Both the number of surface IgM-expressing B cells and CFU-B were higher in the spleen of SCID mice that received NZB grafts than marrow cells from donor BALB/c or NZB.xid mice. Marrow from young NZB donors also reconstituted Thy-1, L3T4 and Lyt2-expressing cells in the spleen to levels higher than observed with young NZB.xid donor cells. The transplantation of marrow from 6-month-old NZB donors made it possible to test whether B lineage cells were present in that tissue and could mediate reconstitution in the normal SCID environment. Marrow from old NZB donors did reconstitute B cells in the marrow and spleen of SCID recipients. The level of reconstitution was comparable to that mediated by young BALB/c cells and twice that of old NZB.xid donor cells. The absolute number of splenic CFU-B was also higher in recipients of old NZB marrow as compared to young BALB/c cells. Old NZB.xid donor marrow reconstituted splenic Thy-1, L3T4 and Lyt2 T cells to levels less than observed with NZB donor cells. Analysis of serum Ig in recipients of old NZB cells indicated higher levels of total IgM as compared to mice engrafted with NZB.xid cells, and anti-single stranded DNA antibodies were detected.

Restriction fragment length polymorphisms of the mouse T-cell receptor gene families

We have studied the restriction fragment length polymorphisms (RFLPs) found in the germline T-cell receptor genes of 25 inbred Mus musculus strains and 8 wild Mus species. Included in the inbred mice tested were several strains which spontaneously develop systemic autoimmune disease. Extensive polymorphism was evident for the variable (V) gene segments of the alpha gene family for both the inbred strains and wild mouse species. Changes in the total number of bands hybridizing with probes for V alpha gene segments suggest that members of a V alpha gene segment subfamily are not closely linked, but are interspersed with members of other subfamilies; that expansion and contraction of the multimembered subfamilies may be an important diversifying factor. Our data obtained with beta gene probes revealed genomic diversity that is much more limited than that seen for the alpha locus. Analysis of inbred mice with probes for the gamma gene locus revealed some RFLPs, but little evidence of expansion or contraction in the numbers of gene segments. Among the autoimmune mice, NZW, NZB, and BXSB/MpJ all display distinctive differences with alpha gene probes. NZW mice have a large deletion of the beta gene family, which has been reported previously. We found no differences to distinguish the MRL/MpJ lpr/lpr mice from non-autoimmune strains.

Genetic contributions to lupus-like disease in NZB/NZW mice

In contrast to parental New Zealand Black (NZB) or New Zealand White (NZW) mice, (NZB x NZW)F1 mice exhibit a lupus-like disease characterized by high levels of immunoglobulin G (IgG) antinuclear antibodies in their serum and a fatal immune-complex glomerulonephritis. At least three gene loci have been identified in NZW mice that could potentially contribute to a T cell-dependent autoimmune disease, including the T cell receptor alpha- and beta-chain gene complexes and the major histocompatibility complex (MHC). The NZW T cell receptor beta-chain complex appeared to be particularly unusual in that the C-beta-1, D-beta-2, and J-beta-2 gene segments have been deleted. Approximately one half of (NZB x NZW)F1 x NZB backcross mice developed severe renal disease and elevated levels of IgG antibodies to double-stranded deoxyribonucleic acid and histone, suggesting that only one dominant gene or closely linked group of genes accounts for the NZW genetic contribution to F1 disease. Despite the extremely unusual nature of the NZW T cell receptor beta-chain gene complex, we found no association of disease expression with the presence of this allele in the backcross mice. There was also no correlation of disease incidence with the presence of the NZW T cell receptor alpha-chain allele. In contrast, nearly 90 percent of the backcross mice with the NZW MHC expressed severe autoimmune disease compared with 12 percent of the mice that did not carry this haplotype. Thus, the NZW MHC or gene(s) linked to this locus appears to be the only dominant NZW genetic contribution to F1 disease. Recent preliminary studies mapping genes that are located centromeric and telomeric to the NZW MHC suggest that the disease-associated gene(s) lies within the MHC.

HLA-DR antigens and anticardiolipin antibodies in northern Italian systemic lupus erythematosus patients

Eighty systemic lupus erythematosus (SLE) patients attending 3 clinical centers were evaluated immunologically and immunogenetically. No HLA class II antigens were found to be significantly associated with SLE in these patients. A highly significant (P = 6.17 x 10(-7) association was observed between anticardiolipin antibodies and DR7. A lesser association (P less than 0.025) was also observed between DR2 and/or DR3 and anti-Ro (SS-A) antibodies. No relationship was found between any DR antigen and anti-Sm/RNP, anti-double-stranded DNA, or anti-La (SS-B) antibodies.

Immunogenetics of SLE and primary Sjögren's syndrome

SLE is a syndrome defined by clinical criteria and by the presence of autoantibodies reactive with nucleic acids and proteins concerned with transcription and translation. Breeding experiments in mice have illustrated the enormous genetic heterogeneity of this syndrome, of which the final common pathway is a widespread immune complex disease. The causes of SLE in humans are likely to be equally multifactorial. Family studies have demonstrated that genetic factors exist, but each factor appears to be a relatively weak disease-susceptibility gene. The major exceptions to this are the very rare complete deficiencies of classical pathway complement components, which are almost invariably accompanied by the development of SLE. Observations of these patients have led to the formulation of hypotheses relating complement and its receptor, CR1, to the defective removal of immune complexes from the circulation.

Nonlinkage of the T cell receptor alpha, beta, and gamma genes to systemic lupus erythematosus in multiplex families

To test the possibility that T cell antigen receptor (TcR) genes are linked to the genes involved in the pathogenesis of systemic lupus erythematosus (SLE), genomic DNA restriction fragment length polymorphisms were studied, using the Southern blot technique, in 5 families with multiple members with SLE, 14 unrelated SLE patients, and 14 normal controls. Polymorphic patterns were detected with probes for all 3 TcR chains, but there was no significant difference in the distribution of the restriction fragment length polymorphism pattern among the patients, the relatives, and the controls. Furthermore, in the families with at least 2 individuals with the disease, each of the 3 TcR chain genes did not cosegregate with the disease. We conclude that TcR alpha, beta, and gamma chain genes are not likely to be linked to genes related to SLE.

T-cell antigen receptor alpha chain polymorphisms in insulin-dependent diabetes

Insulin-dependent diabetes is a chronic autoimmune disease probably mediated by T cells. We examined the alpha chain of the T-cell antigen receptor in two models of this illness (man and BB rat) to determine any association with autoimmune diabetes. We conducted a population study in man, using a human alpha chain probe, pGA-5, and restriction enzyme Bgl 11. Two allelic forms and three RFLP patterns, 2.8 and 3.0 kb homozygous and 2.8/3.0 heterozygous, were detected. There was no difference in the frequency of these RFLPs among the 50 Type I diabetic patients and 48 controls tested. BB rats develop a spontaneous T-cell mediated autoimmune diabetes. The diabetes has been linked in several breeding studies to an undetermined autosomal recessive gene causing T-cell lymphopenia. We were able to differentiate the T-cell antigen receptor alpha chain of the diabetic BB and control BBN rats using the restriction enzyme EcoR1 and a murine alpha chain probe, TT11. The BB rat had a haplotype characterized by the presence of 4.7 and 5.8 kb bands, and the absence of 1.4, 2.2, 2.6, 3.6, 3.9, 4.1, and 6.1 kb bands. In a breeding study with BB and BBN rats, diabetic animals of the F2 generation demonstrated no linkage with the BBs' alpha chain, nor was lymphopenia linked to the alpha chain of the BB rat. These results suggest that autoimmune diabetes is not linked to the T-cell antigen receptor alpha chain in the BB rat, nor is it associated with alpha chain constant region polymorphisms in Type I diabetes in man.

T-cell receptor alpha-chain variable-region haplotypes of normal and autoimmune laboratory mouse strains

We used Southern blotting and mRNA analysis to characterize allelic polymorphisms among genes of the T-cell antigen receptor (TCR) alpha-chain variable-region (V alpha) locus in a large panel of normal and autoimmune-susceptible or autoimmune-contributing strains of laboratory mice. Four major V alpha haplotypes were defined on the basis of multiple restriction fragment length polymorphisms for each of nine V alpha subfamily probes used. Southern blotting also revealed haplotype-specific loss of bands within some V alpha subfamilies, consistent with the deletion of particular V alpha genes or sets of genes from haplotype to haplotype. In contrast to the situation in the V beta locus, however, deletion of entire V alpha subfamilies was not observed. The nature of V alpha allelic variability was further explored by using an RNase protection assay to analyze expressed V alpha mRNA sequences in thymocyte RNA. Such analysis revealed both shared and unique patterns of V alpha mRNA expression among the different haplotypes and supported the conclusion that haplotype differences sometimes involve V alpha gene deletions. Interestingly, a disproportionate number of, but not all, autoimmune-susceptible strains, including NZB, SJL, SWR, PL/J, and NOD, share a common V alpha haplotype. The identification of murine TCR V alpha haplotypes should provide a basis for understanding the role of TCR diversity in normal immunoregulatory and immune-response phenomena, as well as autoimmune-disease predisposition.

In vitro anti-histone antibody production by peripheral blood cells from patients with systemic lupus erythematosus

Anti-histone antibodies (AHA) have been demonstrated frequently in the sera of patients with systemic lupus erythematosus (SLE). In the present studies, we found that peripheral blood mononuclear leukocytes (PBL) from a large subset of SLE patients spontaneously produce elevated levels of AHA in culture. In contrast, detectable production by normal mononuclear cells was extremely rare. Spontaneous production by patients' PBL correlated with both disease activity and elevated serum AHA levels, and thus appeared to reflect in vivo production. Interestingly, spontaneous AHA production was independent of polyclonal B-cell activation as measured by total Ig synthesis in culture. Production also appeared to be T-cell-independent in that cultures depleted of T cells produced AHA levels similar to those of cultures with unseparated PBL. Although PBL from normal individuals rarely produce AHA spontaneously, the presence of histone-specific B cells in normal peripheral blood could be detected after pokeweed mitogen stimulation. The present studies provide a basis for a further understanding of the mechanisms responsible for autoantibody production in SLE.

Tumour necrosis factor-alpha in murine autoimmune 'lupus' nephritis

The (NZB x NZW)F1 hybrid mouse develops a severe autoimmune disease similar to systemic lupus erythematosus in humans. Both the human and murine form of the disease show strong associations with alleles of the major histocompatibility complex (MHC) gene products. The severe form of the disease found in F1 mice is due, in part, to dominant NZW gene(s) mapping with the H-2 complex (the murine MHC). Here we present evidence that the tumour necrosis factor (TNF-alpha) gene, which is located within the H-2 complex (the murine major histocompatibility complex), could be involved in the pathogenesis of lupus nephritis in F1 mice. Thus, a restriction fragment length polymorphism in the TNF-alpha gene correlates with the reduced levels of TNF-alpha produced by NZW mice. Furthermore, replacement therapy with recombinant TNF-alpha induces a significant delay in the development of the nephritis.