Evidence for a B lymphocyte defect underlying the anti-X anti-erythrocyte autoantibody response of NZB mice.

The autoimmune hemolytic anemia of NZB mice is pathogenetically mediated by a genetically prescribed anti-erythrocyte autoantibody response directed to the X erythrocyte autoantigen. The cellular locus of the immunoregulatory defect underlying the anti-X response was explored by adoptively transferring bone marrow cells (BMC) from NZB mice to lethally irradiated histocompatible recipients. Before adoptive transfer, BMC from donor mice were assayed for antigen-binding lymphocytes with receptors for the X autoantigen (X-ABL) by immunocytoadherence assays and for anti-X autoantibody-secreting cells (X-PFC) by plaque-forming cell assays. Twelve weeks after adoptive transfer, splenic lymphocytes from recipient mice were assayed for X-PFC and humoral anti-X autoantibody by Coombs' tests. Transfer of 15 to 30 x 10(6) BMC containing 6 to 12 x 10(3) X-ABL but no X-PFC from 6- to 8-week-old NZB mice to lethally irradiated BALB/c, B10.D2, C57BL/Ks, and DBA/2 mice produced X-PFC in 70% of the recipients. Development of X-PFC was not simply dependent upon available X-ABL since transfer of 15-30 x 10(6) BMC, containing comparable numbers of X-ABL, from BALB/c, B10.D2, C57BL/Ks, or DBA/2 mice to NZB or syngeneic recipients did not produce X-PFC. Transfer of BMC from NZB mice to BALB/c, B10.D2, and DBA/2 mice with weekly administrations of AKR anti-theta antiserum had no effect on the development of X-PFC; Tlymphocyte ablation was evidenced by the absence of theta+ spleen cells. These results suggest that the pathogenetic anti-X response is not genetically prescribed at the level of macrophages, humoral factors, or T cells, but rather appears to be a phenotypic expression of a primary B lymphocyte defect permitting or promoting differentiation of NZB X-ABL.     

Genes on chromosomes 1 and 4 in the mouse are associated with repair of radiation-induced chromatin damage

Early-passage skin fibroblasts from different inbred and congenic strains of mice were X-irradiated (1 Gy), and the number of chromatid breaks was determined at 2.0 h after irradiation. The cells from DBA/2N, C3H/HeN, STS/A, C57BL/6N, BALB/cJ, and AKR/N had 25 to 42 chromatid breaks per 100 metaphase cells (efficient repair phenotype). NZB/NJ had greater than 78 and BALB/cAn had 87 to 110 chromatid breaks per 100 cells (inefficient repair phenotype). Differences between BALB/cAn and BALB/c. DBA/2 congenic strains which carry less than 1% of the DBA/2 genome indicate that two genes, one on chromosome 1 linked to bcl-2-Pep-3 and the other on chromosome 4 closely linked to Fv-1, affect the efficiency with which the cells repair radiation-induced chromatin damage.     

Increased spontaneous polyclonal activation of B lymphocytes in mice with spontaneous autoimmune disease.

Early in life, mice of four kinds [NZB, (NZB X NZW)F1, MRL/1, and male BXSB] with autoimmune disease spontaneously produced far more (greater than 3 S.D.) anti-hapten antibody-forming cells in spleens and greater concentrations of anti-hapten antibodies in sera than immunologically normal strains of mice (AKR, BALB/c, C57BL/6, DBA/1-J, DBA/2J, LG/J, 129, NZW, and female BXSB). This increased nonspecific antibody production by the abnormal animals' B cells correlated well with the spontaneous development of anti-single-stranded DNA antibodies, but not with serum levels of the viral envelope glycoprotein, gp70. These results suggest that the spontaneous formation of autoantibodies in mice whose immunologic disorder is manifested by a lupus-like disease may result from polyclonal activation of B cells by endogenous or exogenous B cell activators.     

IgD allotypic determinants. I. Determinants expressed on murine IgD of the a allotype

Allotypes of membrane IgD of 27 strains of mice were determined with a series of anti-delta reagents, each capable of binding to the IgD of BALB/c spleen cells. One of these reagents is a newly defined allospecific rabbit anti-mouse-delta a. Typing with these reagents reveals the strain distribution of the previously described IgD.36 (Ig5.1) and IgD.43 (Ig5.4) specificities and demonstrates the existence of a new specificity, IgD.45 (Ig5.5). The results confirm the previous subdivision of the Igh-Ce haplotype into Igh-Ce, to which A mice are assigned, and Igh-Cn, to which NZB and NZW mice are assigned. In addition, it is shown that the Igh-Cd haplotype must also be subdivided. AKR mice, which express the a allele at the Igh-5(delta) locus, are designated as possessing the Igh-Cd haplotype while AL/N and C.AL20 mice, which have the e allele at the Igh-5(delta) locus, are assigned a new Igh-C haplotype designation, o.     

Characterization of the antibody response against the type II collagen induced by anti-idiotypic antibody.

We reported that rabbit anti-idiotypic antibody (Ab2) against mAb, termed 1-5 (Ab1) and reactive with human type II collagen (CII) induced antibody response to CII in DBA/1J mice susceptible to collagen-induced arthritis. In the present study, we further characterized the anti-CII antibody response elicited by Ab2 with respect to epitope specificity, putative genetic background, and IgG subclass. Most of anti-CII antibodies (polyclonal Ab3) derived from Ab2-immunized mice were of the IgG1 subclass. We purified polyclonal Ab3, using a CII-coupled immunoadsorbent column and we developed monoclonal Ab3 from Ab2-immunized mice. Both purified polyclonal Ab3 and two monoclonal Ab3s specifically reacted with a selected epitope on CII, recognized by Ab1. The anti-CII antibody response stimulated by Ab2 was observed in DBA/1J (H-2q, Igh-1c) and DBA/2 (H-2q, Igh-1c) mice, but not in the BALB/c (H-2d, Igh-1a) and C57BL/6 (H-2b, Igh-1b) strains, thereby suggesting that the anti-CII antibody response elicited by Ab2 is controlled by the Igh gene.     

Allelic polymorphism of murine IgE controlled by the seventh immunoglobulin heavy chain allotype locus

Two alloantisera against hybridoma-derived IgE detected allotypic determinants expressed on the murine s chain. An antiserum raised in BALB/c mice against monoclonal IgE of C57BL/6 origin reacted exclusively with IgE of strains having Igh-1^b (IgG_2a) allotype. The second antiserum, C57BL/6 anti-BALB/c monoclonal IgE, reacted with IgE of strains having Igh-1^a, Igh-1^d, Igh-1^e and Igh-1^j allotypes. The genetic studies of (BALB/c x C57BL/6)F₁ and backcross F₂ animals indicated that the locus controlling the IgE allotype is linked to the Igh-1 locus. This was further confirmed by the possession of respective IgE allotypes by Igh-C congenic mice, BALB/c and BAB-14, C3H.SW/Hz and CWB/Hz. Thus, the allotype detected on the chain is controlled by the seventh murine immunoglobulin allotype locus, and should be designated as the Igh-7 allotype.Abbreviations used in this paper PCA passive cutaneous anaphylaxis - RID radioimmunodiffusion - i.p. intraperitoneally - EA egg albumin - Igh-C immunoglobulin heavy chain constant region locus - DNP 2,4-dinitrophenyl - PBS phosphate-buffered saline - NMS normal mouse serum - KLH keyhole limpet hemocyanin Visiting investigator supported by the Scientific and Humanistic Development Council from the Central University of Venezuela, currently at the following address: Consejo de Desarrollo Cientifico y Universidad Central de Venezuela, Av. Principal Urb. La Floresta Ota., Silenia Caracas, Venezuela.     

Preferential induction of specific lambda-isotypic antibodies in mice

A high proportion (greater than 40%) of lambda-anti-NP antibodies were induced after the administration of hapten conjugates of the relatively T-independent antigen NP-Ficoll. In 11 of 12 strains, lambda 1 anti-NP antibodies were the predominant isotype. In lambda 1-defective SJL mice, lambda 2,3 anti-NP antibodies were the major species after NP-Ficoll immunization. In contrast, the ability to elicit a high proportion of lambda-anti-NP antibodies with the T-dependent conjugate of ovalbumin, NP-OVA, varied among mouse strains. Igh-1b-bearing mice were high producers of lambda 1 anti-NP antibodies (greater than 70% of the response); DBA/2 and BALB/c mice were moderate (40 to 50%) lambda 1 anti-NP producers, and A.TL, AKR, NZB, and C3H mice were low lambda 1 anti-NP producers (less than 10%) after primary NP-OVA immunization. In the latter group, NP-OVA preferentially elicits kappa-bearing anti-NP antibodies. The parameters that influence the distribution of light chain isotypes were investigated. The preferential induction of lambda-anti-NP antibodies with NP-Ficoll was a) partially influenced by Igh-linked genes, b) adjuvant independent, and c) maintained on prolonged immunization. In contrast, induction of a high proportion of kappa-anti-NP antibodies by NP-OVA is (a) strictly regulated by Igh-linked genes and (b) enhanced after hyperimmunization. The immunochemical, genetic, and cellular bases for these observations are discussed.     

NaCl taste thresholds in 13 inbred mouse strains

Molecular mechanisms of salty taste in mammals are not completely understood. We use genetic approaches to study these mechanisms. Previously, we developed a high-throughput procedure to measure NaCl taste thresholds, which involves conditioning mice to avoid LiCl and then examining avoidance of NaCl solutions presented in 48-h 2-bottle preference tests. Using this procedure, we measured NaCl taste thresholds of mice from 13 genealogically divergent inbred stains: 129P3/J, A/J, BALB/cByJ, C3H/HeJ, C57BL/6ByJ, C57BL/6J, CBA/J, CE/J, DBA/2J, FVB/NJ, NZB/BlNJ, PWK/PhJ, and SJL/J. We found substantial strain variation in NaCl taste thresholds: mice from the A/J and 129P3/J strains had high thresholds (were less sensitive), whereas mice from the BALB/cByJ, C57BL/6J, C57BL/6ByJ, CE/J, DBA/2J, NZB/BINJ, and SJL/J had low thresholds (were more sensitive). NaCl taste thresholds measured in this study did not significantly correlate with NaCl preferences or amiloride sensitivity of chorda tympani nerve responses to NaCl determined in the same strains in other studies. To examine whether strain differences in NaCl taste thresholds could have been affected by variation in learning ability or sensitivity to toxic effects of LiCl, we used the same method to measure citric acid taste thresholds in 4 inbred strains with large differences in NaCl taste thresholds but similar acid sensitivity in preference tests (129P3/J, A/J, C57BL/6J, and DBA/2J). Citric acid taste thresholds were similar in these 4 strains. This suggests that our technique measures taste quality-specific thresholds that are likely to represent differences in peripheral taste responsiveness. The strain differences in NaCl taste sensitivity found in this study provide a basis for genetic analysis of this phenotype.     

Extinction of passive avoidance response in various mouse strains

Dependence of the passive avoidance extinction dynamics on a mouse strain was shown. Mice C57BL/6J and AKR/J extinguished more quickly relative to DBA/2J, CBA/Lac and BALB/c, and this extinction was stable. Individual instability of extinction was characteristic of C3H/HeJ mice. Extinction of the passive avoidance in mice CBA/Lac and BALB/c was slower: with a delay in the beginning and prolonged retention of memory trace of the shock exposure. In DBA/2J mice, the extinction was impaired. These data suggest that DBA/2J, CBA/Lac and BALB/c mice constitute groups of risk with high predisposition to impairment of extinction of memory of aversive events, which is thought to be a symptom of a depressive-like state.     

Characterization of allelic V kappa-1 region genes in inbred strains of mice

Germ line genes encoding mouse Ig kappa-chains belonging to the V kappa-1 group have been isolated from BALB/c, NZB, and CE, three inbred strains of differing kappa haplotype. The V kappa-1A and V kappa-1C germ line genes isolated from BALB/c (Ig kappa c) were identical to those previously described. These are the two major V kappa-1 germ line genes in BALB/c and together account for 40 of the 53 expressed V kappa-1 sequences that have been reported to date. Allelic differences in a single germ line variable region gene (V kappa-1A) in different strains of mice explain the differences in L chain IEF patterns previously associated with the Ig kappa-Ef2 locus. The rearranged kappa-gene expressed in the BALB/c myeloma MOPC-460 has been isolated and found to represent a V kappa-1A somatic variant differing by three nucleotides from the germ line V kappa-1A gene. Germ line genes isolated from NZB (Ig kappa b) and CE (Ig kappa f) show greater than 95% identity with the BALB/c genes over the 1700 nucleotides compared. Comparison by region indicated the greatest conservation of sequence occurs in and around the leader exon followed by the V-region exon. The NZB gene encodes the amino acid sequence found in the myeloma PC-2205, previously designated V kappa-1B. The V kappa-1 gene isolated from CE is likely an allele of the BALB/c V kappa-1C gene as the two share greater than 96% identity over 1700 nucleotides. The CE gene has been designated V kappa-1Cf. Ancient remnants of LINE-1 repetitive elements were detected approximately 400 bp downstream of all of the V kappa-1 genes. These possess greater homology with repetitive elements found near other kappa genes than they do with the native L1Md sequence.     

Susceptibility to immunosuppression by ultraviolet B radiation in the mouse

Irradiation with ultraviolet B (UVB; 290–320 nm) initiates systemic immunosuppression of contact hypersensitivity (CHS). UV dose-responses for suppression of CHS to trinitrochlorobenzene were established in 18 strains of inbred mice. Three phenotypes with significantly different susceptibilities to UV suppression were identified. The phenotypes were: high (HI) susceptibility, 50% suppression with 0.7–2.3 kJ/m² UV (C57BL/6, C57BL/10, and C57L and NZB females); low (LO) susceptibility, 50% suppression with 9.6–12.3 kJ/m² UV (BALB/c, AKR, SJL and NZW), and intermediate (INT) susceptibility, 50% suppression with 4.7–6.9 kJ/m² UV (DBA/2, C57BR, C3H/HeJ, C3H/HeN, CBA/N and A/J). UV suppression was not correlated with skin pigmentation or with the magnitude of the CHS response in non-irradiated animals. Major histocompatibility complex (MHC) haplotype was not correlated with UV suppression in MHC congenic strains B10.D2/oSnJ, B10.D2/nSnJ, B10.BR/SgSnJ, and A.BY/SnJ. There were no sex differences in UV suppression in BALB/c, C57BL/6, or NZW animals. In the autoimmune NZB strain, however, male mice (LO) were seven times less sensitive to UV suppression than NZB female mice (HI). Both sexes of (NZB × NZW)F₁ and (NZW × NZB)F₁ mice were HI, supporting dominance of HI over LO. Thus there are genetic factors and interacting sex-limited factors determining susceptibility to UV suppression. These findings may be of relevance to UV-related diseases such as photosensitive lupus and skin cancer. Correspondence to: F. P. Noonan.     

Detection of Mls-antigens in various mouse strains using a new method

Mice of strains CBA and BALB/c, when injected with lymphocytes from theH-2-compatible Mls-antigen-incompatible strains C3H and DBA/2, respectively, develop a reduced lymphocyte reactivity against cells of the injected strains as measured in the mixed lymphocyte culture (MLC). The mechanism of the development of a depression of the MLC response against Mlsantigens is unknown. In this investigation we have tested the MLC response of lymphocytes from CBA mice preinjected with C3H lymphocytes against cells from 12 different strains. It was observed that the response decreased against cells from strains C3H, AKR, and A/Sn. Infusion of CBA mice with AKR lymphocytes decreased their MLC response against the same three strains. In contrast, infusion of CBA mice with A/Sn lymphocytes reduced their MLC responses against strains C3H, DBA/2, and the congenic strains A/Sn, A.SW, A.CA, and A.BY. BALB/c mice which were infused with DBA/2 lymphocytes developed reduced responses against DBA/2, C3H, and AKR. On the basis of these results we propose that mice of our strains C3H and AKR possess a common Mls-antigen which is strongly stimulatory, and that DBA/2 mice possess a second Mls-antigen which is also strongly stimulatory. The congenic strains A/Sn, A.SW, A.CA, and A.BY, which have differentH-2 complexes, possess a third Mls-antigen which is less stimulatory. The Mls-antigens of the strains listed above seem to exhibit extensive immunological crossreactivity.     

Genetic determinants of resistance to ectromelia (mousepox) virus-induced mortality.

Resistance to ectromelia (mousepox) virus-induced mortality was examined in crosses between susceptible DBA/2J, A/J, and BALB/cByJ mice and resistant C57BL/6J and AKR/J mice. Depending on the cross, resistance to mousepox virus was shown to be determined by one or more independently assorting autosomal loci with dominant alleles for resistance in AKR/J and C57BL/6J mice and recessive alleles in A/J, BALB/cByJ, and DBA/2J mice. A sexual dimorphism in resistance to disease was also observed.     

Host genetic determinants of neurological disease induced by Cas-Br-M murine leukemia virus.

Cas-Br-M is an ecotropic murine leukemia virus (MuLV) of wild-mouse origin that causes neurogenic hind-limb paralysis. By virtue of its N-tropism, the virus replicates well in tissues of mice bearing the n but not the b allele at the Fv-1 locus. To determine if different Fv-1n strains of mice were equally susceptible to virus-induced neurological disease, we inoculated NFS, C3H, DBA/2, CBA, AKR, C58, and NZB mice at birth with Cas-Br-M murine leukemia virus and observed them for the development of tremor and hind-limb paralysis. Three patterns of disease were observed: NFS and C3H mice developed disease within 3 months postinoculation; DBA/2 and CBA mice became affected between 8 and 15 months postinoculation; and no disease was observed in AKR, C58, or NZB mice up to 15 months after infection with Cas-Br-M murine leukemia virus. Studies of genetic crosses between intermediate-latency (DBA/2) or long-latency (AKR) strains with short-latency (NFS) strains showed that intermediate latency and long latency were semidominant traits determined by two or more interacting but independently assorting loci. These genes appear to determine the rate at which the virus replicates and at which viral gene products accumulate in the central nervous system.     

Immunodepressant action of cyclophosphamide in different strains of mice

A study was made of the immunodepressive effect of cyclophosphamide (CP) on mice of 3 strains (BALB/c, CBA, and DBA/2) immunized with sheep red blood cells (SRBC). With the optimal immunizing dose of the antigen (5 X 10(8) SRBC) the most pronounced immunodepression was noted in DBA/2 mice, and with the high dose (6.2 X 10(9))--in DBA/2 and CBA mice. The CP action proved to depend on the dose of the antigen administered; in BALB/c mice a reduction in the number of the antibody-forming cells was the same with both SRBC doses, in DBA/2 mice an increase of the antigen dose led to reduction of immunode pression, and in CBA mice -- to its enhancement (with sufficiently high CP doses). Determination of the rate of oxidative CP hydroxylation by the liver microsomes of mice showed it to be comparatively low in DBA/2 and CBA mice, and much greater in BALB/c mice. It is supposed that the detected differences in the immunodepressive action of CP could be connected with different sensitivity of the target cells and (or) with the peculiarities of its metabolism in mice belonging to different strains.     

New loci from New Zealand Black and New Zealand White mice on chromosomes 4 and 12 contribute to lupus-like disease in the context of BALB/c

New Zealand Black (NZB) and New Zealand White (NZW) mice are genetically predisposed to a lupus-like autoimmune syndrome. To further define the loci linked to disease traits in NZB and NZW mice in the context of the BALB/c genetic background, linkage analyses were conducted in two crosses: (NZW x BALB/c.H2(z))F(1) x NZB and (NZB x BALB/c)F(2). Novel loci linked to autoantibody production and glomerulonephritis, present in both NZB and NZW mice, were identified on proximal chromosomes 12 and 4. The chromosome 12 locus showed the strongest linkage to anti-nuclear Ab production. Additionally, a number of other novel loci linked to lupus traits derived from both the New Zealand and non-autoimmune BALB/c genomes were identified. Furthermore, we confirm the linkage of disease to a number of previously described lupus-associated loci, demonstrating that they are relatively background independent. These data provide a number of additional candidate gene regions in murine lupus, and highlight the powerful effect the non-autoimmune background strain has in influencing the genetic loci linked to disease.     

Evidence for linkage of murine beta 2-microglobulin to H-3 and Ly-4

Murine beta 2-microglobulin exists in 2 electrophoretically distinct forms; C57BL/6 mice possess the basic allele whereas BALB/c, CBA, AKR, and NZB possess the acidic allele. Mice heterozygous for beta 2-microglobulin express both alleles. Analysis of recombinant inbred mice suggests linkage of beta 2-microglobulin to H-2 or H-3. B10.C (28NX) mice (which possess the H-3c allele of BALB/c on a C57BL/10 background) possess the acid allele. Taken together, these results are consistent with the beta 2-microglobulin gene lying on chromosome 2, and being linked to H-3 and Ly-4.     

Single-locus control of the mast cell population in mouse skin

The number of mast cells in connective tissue from dorsal skin varied markedly among mouse strains. Inbred strains of mice were typed into three groups, high (NC and NZB mice), low (B6, B10, and BALB/c mice), and intermediate (C3H/He and DBA/2 mice), by their mast cell content in the skin. However, the strain differences in the number of mast cells was marginal at the age of weaning but became distinct with age. This could be explained mainly by the frequently observed clustering of mast cells in adult NC and NZB mice and the rarely observed clustering in younger mice as well as in adult B10 and BALB/c mice. The breeding experiment revealed that the difference in the number of mast cells between NC and B10 mice was controlled by a single autosomal dominant locus, for which we propose the designation Mcr (mast cell regulator). The role of the Mcr locus with regard to the frequency of the mast cell population in connective tissue is discussed.     

Loss ofHindIII cleavage sites in thed-amino acid oxidase gene in some inbred strains of mice

Summary d-Amino acid oxidase cDNA was amplified by a polymerase chain reaction using RNA extracted from the mouse kidney. When digested withHindIII, the cDNAs of the BALB/c and ddY/DAO^– mice were cleaved into two fragments whereas the cDNA of the ddY/DAO⁺ mice was not. Sequencing revealed that nucleotide-471 of the cDNAs was G in the BALB/c and ddY/DAO^– mice whereas it was substituted for C in the ddY/DAO⁺ mice. This base substitution was the cause of the failure of the cleavage of the cDNA of the ddY/DAO⁺ mice.Examination of other strains of inbred mice showed thatd-amino-acid oxidase cDNAs of A/J, AKR, C57BL/6, CD-1, CF#1, ICR, DBA/2, NZB and NZW mice were cleaved withHindIII into two fragments whereas those of C3H/He, CBA/J and NC mice were not. Genomic DNAs extracted from the mice of these 15 strains were digested withHindIII and hybridized withd-amino-acid oxidase cDNA. A 18.2-kb fragment hybridized with the probe in the C3H/He, CBA/J, ddY/DAO⁺ and NC mice whereas two fragments of 12 kb and 6.2 kb hybridized in the other mice. These results are consistent with those of the cDNAs, confirming the loss of theHindIII cleavage site in the C3H/He, CBA/J, ddY/DAO⁺ and NC mice. The Southern hybridization revealed a loss of a differentHindIII cleavage site in the A/J, AKR, C57BL/6, DBA/2, ICR and NZB mice.The substitution at nucleotide-471 should cause a substitution of an amino acid residue. However, this substitution did not affect catalytic activity ofd-amino acid oxidase.     

Further evidence that BALB/c and C57BL/6 gamma 2a genes originate from two distinct isotypes.

Gene conversion by the corresponding gamma 2b gene has been proposed to explain the multiple differences between the nucleic acid sequences of BALB/c (Igh-1a) and C57BL/6 (Igh-1b) gamma 2a immunoglobulin allelic genes. However, genetic analysis indicates that duplicated forms of gamma 2a genes are not only present in Eastern Asia, but also in European wild mouse populations which suggests a widespread phenomenon. In order to verify whether the gamma 2a-related isotypic genes, namely gamma 2c and gamma 2a, could correspond to those present as alleles in domestic mice (Igh-1b and Igh-1a), a genomic library from Mus m.musculus strain (MAI) was constructed. Extensive mapping of the recombinant phages and Southern blot analysis with several restriction enzymes gave the complete organization of these loci: gamma 2b (18 kb) gamma 2c (17 kb) gamma 2a (14 kb) epsilon. The homology in flanking, coding and intervening region sequences indicates that MAI gamma 2c and gamma 2a related genes correspond to C57BL/6 and BALB/c Igh-1 alleles respectively. Also, Southern blot analysis using several probes derived from exonic and intronic regions between gamma 2b and gamma 2a genes shows a 2.0- to 3.0-kb difference in the distance between gamma 2b and gamma 2a genes of BALB/c strain as compared to C57BL/6. Taken together, these results indicate that BALB/c and C57BL/6 gamma 2a genes could originate from different isotypes.