Influence of the immunoglobulin heavy chain locus on expression of the VK1GAC light chain

The VK1GAC light chain represents the dominant V kappa structure employed in the antibody response of A/J mice to streptococcal group A carbohydrate ( GAC ). Two anti-idiotypic antisera, anti- Id5 and anti- Id20 , with specificity for the VK1GAC light chain were used to examine anti- GAC antibody responses in a series of inbred mouse strains that differ at the heavy chain constant region ( IgCH ) allotype locus. Both idiotypes were expressed in normal and immune sera from mice of most IgCH allotypes, except IgCHb (C57BL/6J) and IgCHf (CE/J). C57BL/6J mice expressed Id5 , but not Id20 , whereas CE/J mice did not express either idiotype. Testing of recombinant inbred strains between BALB/c and C57BL/6 indicated that the pattern of idiotype expression did not correlate with IgCH allotype. The C X B recombinants expressed all three idiotype patterns that were observed in the panel of inbred strains. Testing of allotype congenic mice between BALB/c and C57BL/6 showed that CB.20 and BC.8 mice were Id20 -, whereas BAB-14 mice were Id20 +, indicating that both VH and background (V kappa or regulatory) loci must be derived from BALB/c to obtain Id20 expression. The difference in the frequency of idiotype expression observed between BALB/c and BAB-14 mice indicates that the IgCH locus may exert a quantitative influence on the expression of this light chain. To examine the Id20 -, Id5 + antibodies of C57BL/6 mice, anti- GAC hybridomas were prepared. Of 16 C57BL/6-derived anti- GAC monoclonal antibodies, six were reactive with anti- Id5 and not with anti- Id20 . Isoelectric focusing of the purified kappa light chains from three of these antibodies revealed two distinct spectrotypes that co-migrated with the two known VK1GAC spectrotypes observed with A/J anti- GAC light chains. Idiotypic analysis of in vitro recombinants between the heavy and light chains of A/J and C57BL/6 monoclonal antibodies demonstrated that the C57BL/6 light chains were idiotypically similar to A/J light chains when they were free in solution or paired with A/J heavy chains. These results demonstrate that C57BL/6 mice can express a light chain that is very similar, if not identical, to the VK1GAC light chain, although the light chain is expressed in lower frequency and is paired with a distinct VH structure, which can mask expression of one of the VK1GAC idiotypes. These effects on V kappa expression map to at least three genetic loci: VH, CH, and an unlinked locus.     

A new cross-reactive idiotype-defined family in the phthalate humoral immune response of mice. I. Linkage of VH-Xmp to IgCH allotype locus and mapping with respect to other known VH genes

A cross-reactive idiotype family was previously identified from a very large library of phthalate-specific hybridoma clones. The prototype of this idiotype family is the hybridoma, 2E9, secreting an IgM antibody with phthalate specificity. A portion of both primary and secondary anti-phthalate antibodies elicited in all BALB/c mice tested expresses the 2E9 cross-reactive idiotype. This idiotype has now been found in the anti-phthalate antibodies of several other inbred strains of mice (A/HeHa, DBA/2, and C3Hf/HeHa) tested but not in C57BL/6 mice. Anti-phthalate antibodies elicited from congenic mice BC.8, which express the same IgCH allotype as BALB/c mice but possess C57BL/6 genetic background, contain the 2E9 cross-reactive idiotype, whereas this idiotype is not expressed on the anti-phthalate antibodies derived from another congenic mouse CB.20, which expresses a C57BL/6 IgCH allotype and a genetic background of the BALB/c strain. These results indicate that the gene controlling the 2E9 idiotype is closely linked to the IgCH allotype locus. The 2E9 cross-reactive idiotype was also found in all of the F1 mice (BALB/c X C57BL/6) tested, and the level of expression of this idiotype in the F1 mice was quantitatively equivalent to the allotype/idiotype homozygous mice. The expression of the 2E9 idiotype in the phthalate repertoire has been followed in 12 different wild mouse populations. As expected, the 2E9 idiotype was observed in a large proportion of the wild mouse strains. Surprisingly, several examples of nonconcordance in the expression of idiotype and allotype were observed in these mice. One likely explanation for the linkage breakdown is a crossing over of the heavy chain constant and variable region gene complexes. In the SM/J inbred strain of mice, where such a crossover has occurred, nonconcordance between allotype and 2E9 idiotype expression was demonstrated. By using the recombinant inbred BXD strains of mice, the VH gene encoding the 2E9 idiotype has been mapped with respect to other known VH gene families. Relative to other VH genes the VH-Xmp is situated very close to the IgCH gene region.     

Genetics of the anti-dextran B512 and the autoanti-idiotypic response: codominant expression in F1 hybrids and dichotomy of response and allotype-linked idiotype

The IgM plaque-forming response to the alpha 1-6 epitope of dextran B512 is linked to the Ig-1 heavy chain allotypes j and b characteristic of CBA and C57BL strains, respectively, and the response typically induces the formation of autoanti-idiotypic antibodies that can distinguish between anti-dextran antibodies of CBA and C57BL origin. Nevertheless, some substrains of Balb/c mice (allotype a) and some Bailey recombinant stains give a PFC response although they do not possess allotypes j or b. The anti-dextran antibodies in these strains lack the idiotypes characteristic of either CBA and C57BL antibodies to dextran, but they possess their own particular idiotype. F1 hybrids between two responder strains possessing different idiotypes on their antibodies against dextran, produce both idiotypes and two different autoanti-idiotypic antibodies. CBA(Ig-1b) mice were high responders to dextran and possessed the idiotype of C57BL, whereas C57BL/6(Ig-1a) mice were low responders. The V(H) recombinant strains BAB.14 and CB-8KN that possess the Ig-1b allotype of C57BL, but have some of the V(H) genes from Balb/c and the rest from C57BL/6 were high responders to dextran, but did not possess the C57BL idiotype, suggesting that the genes determining the response against dextran and the idiotype may have different locations in the heavy chain locus.     

Regulation of T15 idiotype dominance. II. Genes unlinked to the Igh locus regulate T15 dominance of the secondary adoptive transfer response to phosphocholine

We have studied the idiotype and fine specificity of the secondary immune response to phosphocholine (PC) in C57BL (B10, B10.D2, and B.C8) and BALB (BALB/c, BAB-14, and C.B20) congenic strains of mice. In vivo IgM responses of mice from these two genetic backgrounds differed in their T15 idiotypic representation. BALB strains expressed the T15 idiotype on greater than 90% of their IgM, PC-specific plaque-forming cells (PFC), whereas C57BL strains expressed the T15 idiotype on approximately 50% of their IgM PFC. All strains examined expressed greater than 75% PC-inhibitable, VHPC idiotype-positive, IgM PFC. The IgG3 and IgA memory responses were similar to the IgM memory response; BALB strains produced a higher proportion of T15+ PFC than C57BL strains; however, the majority of IgG3 and IgA PFC in all strains were VHPC+, and PC-inhibitable. In contrast, the IgG1 memory response was not dominated by T15+, VHPC+, PC-inhibitable PFC in any of the strains tested. The IgG1 PFC required nitrophenylphosphocholine (NPPC) for efficient inhibition. The IgG2 memory response generally mimicked the IgG1 response with respect to idiotype and specificity. These data demonstrate that the representation of the T15 idiotype in the anti-PC immune response is determined by genes outside both the MHC and Igh genetic loci. Control of T15 expression in secondary IgM, IgG3, and IgA anti-PC responses was examined by using a cell-mixing protocol with primed T and B cells from BALB/c and B10.D2 mice. T15 representation in these responses was determined by the genotype of the B cell, not by the genotype of the helper T cell. Similarly, the B cell genotype was responsible for the idiotypic profile of a primary, in vitro, T-dependent, anti-PC response.     

A comparison of the IgG isotype expression in the so-called thymus-independent immune responses to alpha(1----3) and alpha(1----6) dextran

This paper presents data on the IgG antibody response against two "thymus-independent" dextran (Dex) antigens from Leuconostoc mesenteroides, alpha(1----3) Dex B 1355S and alpha(1----6) Dex B 512F in BALB/c and C57BL/6 mice, which are considered to be responders or low responders to the respective antigen. The data point toward three common rules governing the two anti-Dex responses despite immunogenetic and antigenic disparities: (1) age dependency of the IgG isotype regulation of the response; (2) down-regulation of IgG isotype expression by T cells; and (3) individually determined preposition for IgG isotype formation in a given animal.     

Cross-induction of predominant NPb idiotypic antibodies with derivatives of (4-hydroxy-3-nitrophenyl) acetyl

Immunization of C57BL/6 mice with bovine gamma-globulin (BGG) conjugated with (4-hydroxy-3-nitrophenyl) acetyl (NP) induced a population of anti-NP antibodies that bear predominantly lambda light chain, exhibit heteroclitic affinity for heterologous NP derivatives, and share NPb idiotype. The present study analyzes the idiotypes of antibodies induced with BGG conjugated with the iodo-, bromo-, or nitro-NP derivatives (NIP, NBrP, and NNP). NIP-BGG, NBrP-BGG, and NNP-BGG, induce specific antibodies bearing NPb idiotype in C57BL/6 or C57BL/10 congenic mice, but not in many other inbred strains. Furthermore, the quantity of NPb idiotype in immune sera from various mouse strains immunized with NIP-BGG, NBrP-BGG, and NNP-BGG was similar to that in sera from mice immunized with NP-BGG. Anti-idiotypic antisera against C57BL anti-NP, anti-NIP, or anti-NBrP antibodies exhibit extensive idiotype binding of specifically purified B6 anti-NP, -NIP, -NBrP, and -NNP antibodies. These purified antibodies contain a high percentage (greater than 70%) of lambda-chain-bearing molecules. The data indicate that an extensively shared repertoire composed of predominantly lambda-bearing NPb-positive idiotypic antibodies is used in response to NP and its derivatives in C57BL mice.     

Comparison of the murine humoral immune response to recombinant simian virus 40 large tumor antigen: Epitope specificity and idiotype expression

Baculovirus-derived recombinant simian virus 40 (SV40) large tumor antigen (SV40 T-Ag) was used to immunize inbred strains of mice to compare the humoral immune responses. Specifically we examined the epitope specificities and idiotype (Id) expression on anti-(SV40 T-Ag) responses induced in BALB/c and C57BL/6 inbred strains of mice. The predominant SV40 T-Ag epitopes recognized by the anti-(SV40 T-Ag) responses appeared to differ between these two inbred strains, this being based on the ability of sera to inhibit the binding of several murine monoclonal antibodies specific for SV40 T-Ag. In addition, anti-(SV40 T-Ag) responses produced in C57BL/6 mice failed to express a previously described cross-reactive Id expressed in the anti-(SV40 T-Ag) response in BALB/c mice. This cross-reactive Id is detected by a mouse monoclonal anti-Id, designated 58D, which has been shown to represent a potential focal point for manipulating the humoral immune response to SV40-induced tumors in BALB/c mice. Together, these data indicate that the functional duality of the humoral immune response, as assessed by epitope recognition and Id expression, differs between these two inbred strains of mice when immunized with a recombinant SV40 T-Ag.     

The effect of aging on the induction of humoral and cellular immunity and tolerance in two long-lived mouse strains.

Aging is a complex process that adversely affects most if not all components of the immune system. In this report, two long-lived mouse strains have been compared in ability to generate both antigen-specific immunity and tolerance. Although CBA/CaJ mice produced high levels of antibody following injection of aqueous preparations of aggregated human gamma-globulin (AHGG), C57BL/6 mice made only meager antibody responses to such preparations. Age dramatically affects the humoral anti-HGG response to aqueous AHGG in both strains, but the meager response of young C57BL/6 mice was at insignificant levels in aged C57BL/6 mice. Conversely, both mouse strains generated good responses following injection of HGG in complete Freund's adjuvant at both the T and B cell level as evidenced by in vitro antigen-specific T cell proliferation and anti-HGG antibody production. Aged mice of both strains showed a marked decrease in the production of serum anti-HGG antibody in comparison to young mice. Although the antigen-specific T cell proliferative response was significantly decreased in aged CBA/CaJ mice, such proliferation was not affected in aged mice of the C57BL/6 strain. Removal of CD8+ cells from lymph node T cells of either young or aged C57BL/6 mice did not increase the antigen-specific proliferative response, suggesting that loss of CD8+ suppressors during the aging process is not responsible for the high level of antigen-specific T cell proliferation in aged C57BL/6 mice. Tolerance to HGG was readily induced in both young and aged C57BL/6 and CBA/CaJ mice although aged mice demonstrate a modest resistance to tolerance induction when compared to their young counterparts. This resistance was observed in both antibody production and antigen-specific T cell proliferation.     

Idiotypic analysis of a monoclonal anti-Sm antibody. II. Strain distribution of a common idiotypic determinant and its relationship to anti-Sm expression

The idiotypes borne by Y2, a monoclonal anti-Sm antibody of MRL-lpr/lpr mouse strain origin, were investigated to elucidate genetic mechanisms in this autoantibody response. An anti-Y2 anti-idiotypic antiserum was raised in a rabbit and was rendered specific for idiotype by extensive absorption with globulins of the B6 and BALB/c strains as well as the BALB/c myeloma UPC 10. By using a sensitive assay for idiotype by inhibition ELISA, the Y2 determinant was found to be commonly expressed in sera of MRL-lpr/lpr and MRL-+/+ mice. Moreover, sera of several normal strain mice also bore the idiotype and, in mice bearing the lpr gene, idiotype levels were increased 1.5 to fivefold, even in the absence of a serum anti-Sm response. The relationship of this idiotype to anti-Sm expression was further assessed by determining the idiotype content of affinity-purified anti-Sm antibodies from MRL-lpr/lpr mice. Anti-Sm from serum pools or individual animals showed no significant enrichment of the Y2 idiotype in comparison to unselected MRL-lpr/lpr IgG. These results suggest that the Y2 idiotype defines only a minor component of the anti-Sm autoantibody response, and that most antibodies with this determinant express other antigenic specificities.     

Genetics of the alpha 1,6-dextran response: expression of the QUPC52 idiotype in different inbred and congenic strains of mice

Antibodies to dextran B512 were raised in various strains of mice and were assayed by a radioimmunoassay procedure. Idiotypic antibodies to the IgA(k) dextran B512 binding myeloma proteins QUPC52 and W3129 of BALB/c origin were prepared in rabbits. After adsorption each antiserum was specific for the immunizing myeloma protein and did not react with hundreds of other myeloma proteins; nonetheless, antibodies to dextran B512 from various strains of mice cross-reacted in these test systems. Of the 2 idiotypes tested, the W3129 idiotype was more universally expressed in different strains of mice. The QUPC52 idiotype was the predominant idiotype in BALB/c anti-dextran B512 antibodies and was found in only a few other inbred strains. Using a battery of congenic and inbred strains, it was shown that the QUPC52 idiotype was controlled by genes linked to the Igh complex locus (chromosome 12) and to the Ig kappa complex locus (chromosome 6). The W3129 idiotype was found in a number of stocks of mice in the genus Mus recently isolated from the wild. The QUPC52 idiotype thus far was found only in inbred mice.     

The<Emphasis Type="Italic"> Sr1</Emphasis> gene that controls diversity of the anti-inulin antibody response maps to mouse chromosome 14

Previous studies demonstrated that the diversity of the antibody response of mice to the inulin (In) determinant of bacterial levan is regulated by the gene Spectrotype Regulation 1 ( Sr1). BALB/c mice produce a monoclonal anti-In response as shown by isoelectric focusing analysis. In contrast, the anti-In antibody response of (BALB/cxC57BL/6)F1 mice is significantly more heterogeneous. We performed a backcross and a genome-wide scan with microsatellite markers and found that Sr1 is tightly linked to D14Mit121 on chromosome (Chr) 14. This location for Sr1 was supported by analysis of CXB Recombinant Inbred strains. We further confirmed this by finding that the Chr 14 congenic mouse strain B6.C-H8 lacks the C57BL/6 allele of the Sr1 gene, indicating that Sr1 is located in the segment of Chr 14 replaced with BALB/c donor DNA. These data place Sr1 near to or coincident with the Tcra/Tcrd T-cell receptor gene complex and suggest a role for T cells in diversifying the anti-In response.     

A cross-reactive idiotype, QUPC52 IdX, present on most but not all anti-alpha (1 replaced by 6) dextran-specific IgM and IgA hybridoma antibodies with combining sites of different sizes

Seven BALB/c IgM, 4 BALB/c IgA, and 1 C57BL/6 IgA anti-alpha (1 replaced by 6) dextran hybridoma antibodies were characterized idiotypically. Five of the 7 IgM and all 4 BALB/c IgA proteins bear a cross-reactive idiotype present on the anti-alpha (1 replaced by 6) dextran BALB/c myeloma protein QUPC52 and on a majority of anti-alpha (1 replaced by 6) dextran antibodies in BALB/c mice. Of these 9 monoclonal antibodies, some have combining sites as large as 6 glucose residues, and some have combining sites as large as 7 glucose residues. Individual idiotypes present on QUPC52 are differentially expressed on the 9 hybridoma proteins that bear the cross-reactive idiotype. One BALB/c IgM hybridoma protein and the C57BL/6 IgA hybridoma protein did not react with anti-QUPC52 idiotypic antibodies; another BALB/c IgM hybridoma antibody showed only marginal reactivity.     

Strain-dependent differences in responses to exercise training in inbred and hybrid mice

The aim of this study was to characterize the response to exercise training in several mouse strains and estimate the genetic contribution to phenotypic variation in the responses to exercise training. Male mice from three inbred strains [C57Bl/6J (BL6), FVB/NJ (FVB), and Balb/cJ (Balb/c)] and three hybrid F(1) strains [CB6F1/J (CB6 = female Balb/c x male BL6), B6F F(1) (female BL6 x male FVB), and FB6 F(1) (female FVB x male BL6)] completed an exercise performance test before and after a 4-wk treadmill running program. Distance was used as the primary estimate of endurance exercise performance. FVB mice showed the greatest response to training, with five- to sevenfold greater increases in distance run compared with BL6 and Balb/c strains. Specifically, BL6, FVB, and Balb/c strains increased distance by 33, 172, and 23%, respectively. A similar pattern of changes across strains was observed for run time (17, 87, and 11%) and work (99, 287, and 57%). As a group, F(1) hybrid mice derived from BL6 and FVB strains showed an intermediate response to training (61%). However, further analysis indicated that training responses in FB6 F(1) mice (80%) were approximately 2.5-fold greater than responses in B6F F(1) mice (33%, P = 0.08). A similar pattern of changes between FB6 and B6F F(1) mice was observed for run time (44.5 and 17%) and work (141 and 59%). These data demonstrate that there are large strain-dependent differences in training responses among inbred mouse strains, suggesting that genetic background contributes significantly to adaptation to exercise. Furthermore, the contrasting responses in B6F and FB6 F(1) strains show that a maternal component strongly influences strain-dependent differences in training responses.     

Differences in antibody production against mouse hepatitis virus (MHV) among mouse strains

Several strains of mice were examined for antibody production after intranasal inoculation with a low virulence strain of mouse hepatitis virus (MHV), MHV-NuU. C57BL/6N mice were shown to be high responders in the production of complement fixing (CF) antibody as compared to C3H/HeN, BALB/c-AnN, DBA/2N mice. F1 hybrids B6C3 and BDF1 from C57BL/6N mice, showed CF antibody responses as high as C57BL/6N, suggesting that high responsiveness is genetically controlled. All these mouse strains were able to produce high titred neutralizing antibody to MHV.     

Characterization of cardiomyocyte excitation-contraction coupling in the FVB/N-C57BL/6 intercrossed "chocolate" brown mice

Mice are extensively used for gene modification research and isolated cardiomyocytes are essential for evaluation of cardiac function without interference from non-myocyte contribution. This study was designed to characterize cardiomyocyte excitation-contraction coupling in FVB/N-C57BL/6 intercrossed brown mice. Mechanical and intracellular Ca(2+) properties were evaluated using an IonOptix softedge system including peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR(90)), maximal velocity of shortening and relengthening (+/- dL/dt), intracellular Ca(2+) rise and decay rate. Resting cell length was longer in age- and gender-matched C57BL/6 and brown mice compared to FVB strain. PS and +/- dL/dt were significantly lower in brown mice compared to FVB/N and C57BL/6 groups. TPS was shortened in C57BL/6 mice and TR(90) was prolonged in brown mice compared to other groups. Resting intracellular Ca(2+) level and single exponential intracellular Ca(2+) decay constant were comparable among all three mouse lines. Rise in intracellular Ca(2+) in response to electrical stimulus was higher in C57BL/6 mouse myocytes whereas bi-exponential intracellular Ca(2+) decay was faster in brown mice. Myocytes from all three groups exhibited similar fashion of reduction in PS in response to increased stimulus frequency. These data suggest that inherent differences in cardiomyocyte excitation-contraction coupling exist between strains, which may warrant caution when comparing data from these mouse lines.     

Analyses of Idiotypes on Anti-α-1, 6-Dextran Antibodies in Mice

When mice of strains C57BL/6, C3H/He, and BALB/c were immunized with native dextran B512, only a small amount of IgM antibody was produced, but a substantial amount of anti-dextran antibody of IgG class was produced after immunization with a conjugate of dextran T10 and keyhole limpet hemocyanin regardless of the mouse strain used. Isoelectric focusing (IEF) spectra revealed limited heterogeneity of anti-dextran antibody of IgG class with strict consistency in all individual sera from C57BL/6 mice, even after secondary immunization, whereas antibodies from C3H/He and BALB/c mice showed more heterogeneous IEF spectra with some individual variations. Rabbit anti-idiotypic (Id) antibodies were raised by immunization with a subfraction of anti-dextran antibody of IgG class from C57BL/6 mice, which showed major bands focused at around pH 7.7 upon IEF. It was found by using the anti-Id antibodies that virtually all anti-dextran antibody molecules of both IgG and IgM classes from C57BL/6 mice possessed common Id determinants which can be classified into two specificities, one specific for antibody from C57BL/6 mice and the other cross-reactive with antibodies from BALB/c and C3H/He mice. About 80% of the antibody molecules from BALB/c and less than 20% of those from C3H/He mice were positive for the interstrain cross-reactive Id. Both Id determinants seemed to be closely related to the antigen binding sites, or at least to reside in the vicinity of the antigen binding sites of anti-dextran antibody.     

Inheritance of idiotype expression unlinked to the H chain allotype locus. Novel features of genetic control in the Ia.7 system

We have observed a pattern of inherited idiotype expression in three mouse strains that is unexpected from the genetics of the strains: a dominant idiotype that was expressed at high levels in two parental strains was expressed only at low levels in a heavy chain allotype congenic strain derived from them. In the C3H.SW strain, the antibody response to the class II MHC Ag I-E is of limited diversity, with dominant expression of an idiotype and the V kappa 21 L chain. The C57BL/10 strain expresses the same idiotype at high levels, whereas the CWB/12 strain, which was derived by replacing the Ig H chain Igh-Cj allele of C3H.SW with the Igh-Cb allele derived from C57B1/10, has been found to express little of this dominant idiotype. CWB/12 responds, with titers equal to those of the parental strains, to the I-E epitope responsible for dominant idiotype expression, and it expresses normal V kappa 21 levels; thus deficiencies in epitope-specific responsiveness or in V kappa 21 expression cannot explain the low Id expression in CWB/12. Furthermore, Southern blot analysis of three VH families gave no evidence of recombination within the the VH locus of CWB/12, which was Igh-Vb throughout. Black-cross analysis demonstrated that expression of the dominant idiotype segregated independently of Ig allotype, and was therefore due to genes unlinked to the H chain gene locus. To our knowledge, this pattern of Id expression is unprecedented, and indicates the need for caution in the interpretation of studies using allotype congenic strains. It also demonstrates a role for genes outside the Igh locus in the control of Id expression.     

Genetic characterization of a polymorphic murine cell-surface glycoprotein

As described in the preceding paper, monoclonal antibodies have been raised by immunization of rats with mouse hematopoietic cells which detect a major cell-surface glycoprotein (M_r=95 000) of mouse bone-marrow cells of the granulocytic series. While most of the monoclonal antibodies detect this molecule on bone-marrow and spleen cells of all mouse strains, two antibodies recognize alternative allelic forms of the molecule. One alloantigen is expressed in all the remaining inbred strains examined. The alloantigens are codominantly expressed on the cells of F₁ mice. Backcrosses of DBA/2 and C57BL/6 with F₁ mice (B6D2F₁) confirmed that a single genetic locus is involved in the expression of the two antigenic forms and demonstrated linkage to Ly-m11 which has previously been mapped to mouse chromosome 2. These genetic mapping experiments and the biochemical properties of the glycoprotein suggested that it might be identical to a glycoprotein first identified on murine fibroblasts by Hughes and August and designated Pgp-1. This has been firmly established by exchange of monoclonal antibody reagents and sequential immunoprecipitations.     

Strain differences in the development of auto-anti-idiotypic antibody regulation with age: genetic linkage to the Igh-C locus

The effect of age on the appearance of anti-idiotype (Id)-blocked, hapten-augmentable plaque-forming cells (PFC) in various strains of mice was investigated. Strains of mice at 2 and 6-11 months of age were immunized with 500 micrograms trinitrophenylated bovine gamma-globulin (TNP-BGG) in complete Freund's adjuvant (CFA) intraperitoneally. Splenic IgM and IgG anti-TNP PFC responses were assayed for anti-Id-blocked, hapten-augmentable PFC 14 days after immunization. It was found that strains differ with regard to the age at which they produce anti-Id-blocked, hapten-augmentable PFC. C57BL/6J (B6), DBA/1J, and C3H/HeJ mice produced a significantly high percentage of hapten-augmentable IgG anti-TNP PFC at 8-9 months of age as compared with the 2-month-old group. In contrast, 129/J, AKR/J, and C57L/J mice produced a significantly low percentage of hapten-augmentable PFC at 6-7 months of age as compared with the 2-month-old group. The CBA/J mice were high-hapten-augmentable plaque producers at both 2 and 7 months of age. SJL/J mice were, on the other hand, low producers at 2 and 11 months of age. Immune sera from high hapten-augmentable plaque-producing strains caused a hapten-reversible block of plaque formation by spleen cells from TNP-BGG-immune C57BL/6J mice and also revealed anti-(anti-TNP F(ab')2-IgG) titer as assayed by passive hemagglutination. This PFC-inhibiting activity in the immune sera of old C57BL/6J mice was an antibody of the IgG2a and IgG3 classes, lacked anti-TNP antibody activity, but reacted with anti-TNP antibody of C57BL/6J origin. Genetic analysis between high hapten-augmentable plaque production and allotypes in the (129/J X B6) crosses of the same H-2b haplotypes revealed that all of the backcrosses and F2 with high hapten-augmentable plaque production had the Igh-1a allele of the high-producer, 129/J mouse. In contrast, the crosses with low hapten-augmentable plaque production were homozygous for the Igh-1b allele of the low-producer, B6 mouse. The data suggest strain differences in the development of auto-anti-idiotypic antibody regulation with age which may be controlled by a gene(s) linked to the Igh-C locus.     

用rAAV8-1.3HBV制备两种品系小鼠乙型肝炎病毒感染模型的比较研究

我们先前用rAAV8-1.3HBV静脉注射C57BL/6小鼠成功地制备了慢性乙型肝炎病毒(Hepatitis B virus,HBV)感染模型。为了探讨不同品系的小鼠对rAAV8-1.3HBV静脉注射是否具有不同反应,本研究比较了C57BL/6和BALB/c小鼠静脉注射重组病毒后外周血中HBV抗原和抗体水平、病毒载量和肝脏组织HBcAg表达情况,以及不同剂量重组病毒注射与这些指标的关系。将低(4×109 Viral genome,vg)、中(4×1010vg)和高(4×1011vg)三种剂量的rAAV8-1.3HBV通过尾静脉注射至C57BL/6和BALB/c小鼠,分别利用ELISA和荧光定量PCR方法检测血清中的HBV抗原、抗体水平以及HBV DNA,利用免疫组化检测肝脏组织HBcAg的表达。结果发现,对于C57BL/6小鼠,三种不同剂量rAAV8-1.3HBV注射均可造成100%小鼠出现HBV持续感染;血清HBsAg、HBeAg和HBV DNA以及肝组织HBcAg稳定表达超过8个月,其表达水平随重组病毒注射剂量的增加而升高,高剂量注射时可造成超过40%的肝细胞感染HBV,血清中HBV DNA可达105 IU/mL以上;未检测到针对HBV的抗体。对于BALB/c小鼠,三种不同剂量rAAV8-1.3HBV注射也可造成100%小鼠出现HBV持续感染;血清HBeAg和HBV DNA以及肝组织HBcAg稳定表达超过8个月,但是血清HBsAg在重组病毒注射2周之后显著下降甚至消失;在中剂量注射组的BALB/c小鼠血清中检测到低水平的Anti-HBs;血清HBeAg和肝组织HBcAg的表达水平随重组病毒注射剂量的增加而增高,并且各剂量组表达水平均高于C57BL/6小鼠,高剂量注射时可造成超过50%的肝细胞感染HBV。本研究表明,低至4×109 vg剂量的rAAV8-1.3HBV注射即可造成C57BL/6和BALB/c两种品系小鼠出现HBV持续感染,并且HBV复制水平随重组病毒注射剂量增加而增高;BALB/c小鼠对HBV的免疫反应强于C57BL/6小鼠,可以产生针对HBsAg的体液免疫反应而使血清HBsAg转阴,但无法清除携带HBV的肝细胞。