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Preferential assignment of allotype a1 globulin for the production of early IgM anti-para-azobenzenearsonate antibodies in heterozygous a1a3 rabbits.

Rabbits of allotype a1a3 were injected on days 0, 2, and 4 with mixtures containing equal amounts of pigeon erythrocytes (Prbc) coupled to para-azobenzenearsonate (AA) and to para-azobenzene-N-trimethylammonium (TMA). On day 6, the allotypes of antibody from plaque-forming cells (PFC) of the blood were determined by observing the inhibition of plaque formation by anti-allotype sera. Anti-AA PFC appeared to consist for the most part of cells making antibody of allotype a1 since 65% of them were inhibited by anti-a1 serum and only 8% by anti-a3. Anti-TMA PFC, on the other hand, appeared to consist mostly of cells making antibody of allotype a3, since less than 1% of them were inhibited by anti-a1 but 47% by anti-a3. Antibody allotype for spleen PFC was also determined on day 6 and was similar to that found for blood PFC. Anti-AA PFC were inhibited 74% by anti-a1 serum and 15% by anti-a3 whereas anti-TMA PFC were inhibited 19% by anti-a1 and 43% by anti-a3. Serum hemolysin specific for AA hapten from a1a3 animals was also strongly inhibited by anti-a1 serum but not by anti-a3 whereas the converse was true for hemolysin against TMA hapten. The a1a3 rabbits, in whcih the anti-AA was restricted to allotype a1, were mated to produced homozygous a3a3 animals. When the PFC and serum antibodies of these a3a3 offspring were examined by specific inhibition, the anti-AA activity was found to be of allotype a3 rather than being a-negative. The number of anti-AA PFC in the blood of a3a3 rabbits was lower than that in blood of a1a3 or a1a1 animals. In addition, the TMA hapten appeared to inhibit the response to the AA hapten. Thus a1a3 rabbits immunized with AA-Prbc alone had 14-fold more anti-AA PFC or 18-fold higher anti-AA hemolysin titer than a3a3 animals immunized with both AA-Prbc and TMA-Prbc. Our results are discussed in relation to various explanations which have been offered for an imbalance of allotypes in a given antibody.

Amino Acids↗

Structural variability of rabbit secretory components. Allotype-associated differences in the third, fourth, and fifth domains.

We have previously shown (Frutiger, S., Hughes, G. J., Hanly, W. C., Kingzette, M., and Jaton, J.-C. (1986) J. Biol. Chem. 261, 16673-16681) that limited tryptic digestion of the high Mr form of rabbit secretory component of allotypes t61, t62, and t63 generates two major fragments, the NH2-terminal domain and a 40-kDa fragment encompassing domains 3, 4, and 5. Similarly, from the low Mr form of secretory component, (SC) the NH2-terminal domain, together with a 30-kDa fragment containing domains 4 and 5, were released. These fragments were used as inhibitors in a sensitive competitive binding radioimmunoassay with noncross-reactive rabbit alloantisera to study the distribution and localization of the major allotype-specific allotopes within the SC polypeptide. The 40-kDa fragments were shown to inhibit the 125I-labeled intact SC/anti-SC allotype reaction to the extent of 90%, i.e. nearly as well as the intact homologous high Mr SC form. In contrast, the NH2-terminal fragments (domain 1) were not inhibitory. The low Mr SC of each allotype was less inhibitory on a molar basis than the homologous high Mr SC polypeptide, an observation compatible with the deletion of domains 2 and 3 in the smaller polypeptide (Deitcher, D. L., and Mostov, K. E. (1986) Mol. Cell. Biol. 6, 2712-2715; Frutiger, S., Hughes, G. J., Fonck, Ch., and Jaton, J.-C. (1987) J. Biol. Chem. 262, 1712-1715). The structural correlates of the allotypic specificities were evaluated by comparative peptide mapping of the 40-kDa fragments (allotypes t61, t62, and t63). The data suggest that the t61 allotype structure differs significantly from the t62 and t63 structures, the latter two being much more related to each other than to t61. These findings are in full agreement with the serological data. The inhibition results suggest that the major allotype-specific, noncross-reactive allotopes of SC are distributed throughout domains 3, 4, and 5, even though domain 4 appears to be more conserved than domains 3 and 5 between the allotypes t61 and t63. Seven amino acid substitutions between t61 and t63 have been detected within domains 3, 4, and 5.

Amino Acid Sequence↗

Rabbit secretory components: identification of a third allotype, t63.

A third allotype of rabbit secretory component has been identified. The allotype previously referred to as t62 by our laboratory can now be subdivided into two allotypes, t62 and t63, with alloantisera capable of discriminating between the two. Results of family studies are consistent with a three allele system (t61, t62 and t63) at the t-locus. By SDS PAGE, electrophoretic mobilities of the multiple SC bands for each of the three allotypes are characteristic of the allotype; the apparent molecular sizes of the bands of the t62 allotype are 2 to 3 kDa lower than those for the t61 allotype. The banding patterns of the t61 and t63, although similar, are not identical to each other. Results of serologic cross-reaction studies and of tryptic peptide mapping studies suggest multiple structural differences between the allotypes as well as a closer relationship between t62 and t63 than between either of these allotypes and t61.

Alleles↗

The structural basis of rabbit VH allotypes: serologic studies on a1 H chains with defined amino acid sequence.

The amino acid sequences for the VH regions of three homogeneous antibodies elicited by type III pneumococcal vaccine were determined. All three antibodies had the group a allotype a1. Two of the antibody H chains (3372, 3381) had identical amino acid sequences in all framework positions that are considered correlates of the VH allotype, whereas the third H chain (3T72) differed from these at positions 15 and 16. The a1 allotypic specificities of the three homogeneous antibodies were compared by quantitative radiobinding and inhibition assays by using both insolubilized anti-a1 antisera and allotypic antiserum fractions rendered specific for the homogeneous antibody 3374. It was found that antibodies 3374 and 3381 are allotypically indistinguishable and have in common an a1 allotypic specificity that predominates in pooled a1 IgG. The allotypic specificity of the 3T72 antibody, on the other hand, was markedly deficient to those of 3374, 3381, and the a1 IgG pool. This correlation of allotypic difference with amino acid sequence variation at position 15 and 16 of the H chain indicates the involvement of these two residues in a major a1 allotypic determinant.

Amino Acid Sequence↗

Distribution of nominal and latent IgG (Gm) allotypes in plaques of multiple sclerosis brain.

Concentrations of IgG allotypes G1m(1), G1m(3) and G3m(11) in neutral pH eluates from discrete plaques of multiple sclerosis (MS) brain and from white matter of control brain were determined to obtain information about distribution of B cell clones among MS lesions. Within each MS brain a predominant nominal IgG1 allotype was distributed rather homogeneously in all plaques while quantitatively minor allotypes showed some fluctuation. Latent IgG1 allotypes were detected (7-12% of the corresponding nominal allotype level) in some tissue eluates from both MS and control brains, which were homozygous for either G1m(1) or G1m(3). By contrast, the expression of a latent IgG3 allotype, namely G3m(11), was apparently MS restricted. Large amounts of latent allotypes were detected only in recent plaques with lymphoid cells whereas the distribution of total plaque associated IgGs did not correlate with the presence of lymphoid cells. Latent allotypes in recent MS lesions may mark a transient immunological activity which coincides with the infiltration of lymphoid cells and precedes the appearance in these plaques of oligoclonal IgGs, the distribution of which may parallel that of the predominant nominal allotypes.

Adult↗

Double expression of VH region a2 and a3 allotypes in individual rabbit lymphocytes.

This study provides evidence that two VH region a group allotypic specificities are synthesized by individual peripheral blood lymphocytes from a2,3 rabbits. After removal of both allotypes from the cell surface with pronase, three types of allotype-bearing cells, a2, a3, and a2,3 were demonstrable after overnight culture in serum-free medium. Frequently, greater than 50% of the cells that contained allotype on the surface resynthesized both allotypes. In culture, reappearance of allotype was first detectable at 4 hr and increased progressively thereafter to a maximum at 18 hr. During regrowth, the relative proportion of cells showing both markers was maintained. The predominance of cells exhibiting only a3 over those displaying only a2 was also maintained. Reappearance of allotype was inhibited by cycloheximide but was manifested when the antibiotic was washed out. Monospecific anti-a2 antibodies could completely suppress the resynthesis of homologous allotype in culture and prevent the regeneration of a2 in double-bearing cells. Likewise, anti-a3 in cultures was usually specifically suppressive for a3 allotype; however, the double producers were only partially depleted.

Animals↗

Quantitation of mouse immunoglobulin allotypes by a modified solid-phase radioimmune assay.

Allotype-reactive polystyrene tubes were made by first coating their inner surface with immunglobulin (Ig) solutions containing the allotype of interest; this was followed by the application of anti-allotype antibody. The latter was covalently cross-linked to the adsorbed allotype antigen by means of glutaraldehyde to prevent the dissociation of antibody from the surface of the tube in subsequent steps (glutaraldehyde treatment did not affect the specificity of these tubes). Under conditions of antibody excess, allotype-reactive tubes were treated next with 125I-labeled 7S Ig from standard solutions in order to estimate the concentration of Ig allotypes in these solutions. Then, to determine serum allotype concentrations, we used the standard solutions and the serum unknown to carry out competition experiments between labeled and unlabeled allotype antigen. Quantitation of serum Ig allotypes in this way featured a high signal to noise ratio (30 to 100), an error estimate of 3 to 7%, and sensitivity in the nanogram range.

Animals↗

[Allotypes of swine serum proteins].

A series of intraspecific immunizations of pigs by whole blood serum in complete Freund's adjuvant was performed. Four allo-antisera to different serum allotypes were obtained. These allotypes were assigned to A1, B1, C1 and D1. The results of identification show that the allotype A1 is probably a marker of immunoglobulin G. The allotypes B1, C1 and D1 were established to belong to different alpha-globulins, D1 being a marker of lipoprotein. Two geographically isolated populations of white large breed were tested. Two allotype combinations were found to be independent of one another and of sex. Significant differences in allotype frequency between two populations were only established for the G1 (F = 0.142 and 0.334; P less than 0.01). In both populations allotype B1 has the frequency 1.0, the frequencies of allotype A1 being 0.734 and 0.747. Most rare is the allotype D1 (F = 0.078 and 0.082).

Alleles↗

An allotype-associated polymorphism in the gamma3 promoter determines the germ-line gamma3 transcriptional rate but does not influence switching and subsequent IgG3 production.

The human IgG3 (b) allotype is associated with a high and the (g) allotype with a low mean serum level of IgG3 which is due to a low frequency of B cell switching in the latter. In the present study, we found a polymorphism in position -73 (C --> A), located in the 4th NF-kappaB site of the germ-line (GL) gamma3 promoter, resulting in a significant decrease of both the basal and induced activity in the (g) allotype-associated promoter. Over-expression experiments also showed that this polymorphism reduced the synergistic activation of the promoter by Stat6 + NF-kappaB p50 / p65 or Stat6 + C / EBPgamma. A low level of GL gamma3 transcripts was also observed in individuals carrying the (g) allotype-associated promoter region. However, an individual homozygous for a crossover between the promoter and switch region, i. e. with a (g) allotype-associated promoter and a (b) allotype-associated switch region, showed a normal level of switching and IgG3 serum level. This suggests that although the (g) allotype-associated promoter is functionally inferior to that of the (b) allotype-associated promoter, these differences do not affect switching and final production of IgG3 and that polymorphisms in the switch region are more important in controlling this process.

B-Lymphocytes↗

Genetic chasing of T helper cell idiotype and allotype genes.

The present experiments were performed to study whether the genes responsible for the expression of T-idiotypes and allotypes could be mapped in relation to immunoglobulin (Ig) heavy chain V- and C-genes. Use was made of our antiserum 5936, which detects idiotypes in B6 and anti-B10.BR sera and on Lyt-1+, 2.3-B6 anti-B10.BR T-cell populations, and antiserum 6036, which detects allotypes on Lyt-1+, 2.3-B6 T cells, but which does not react against Ig. The reactivity of these antisera with T cells from (B6 X C3H.OH) X C3H.OH backcross mice and CBA-allotype congenic B6 mice was investigated because 5936 idiotypes and 6036 allotypes appeared to be associated with Igh-1b genes (B6) and not with Igh-1j genes (C3H.OH,CBA). Our results will show, first, that 5936 idiotypes on Lyt-1+, s.3-B6 anti-B10.BR T cells are synthesized by genes linked to Igh-1b allotype genes and they are situated either within Ig heavy chain V-genes or centromeric to them. Second, our results will show that 6036 allotypes on Lyt-1+, 2.3-B6 T cells are produced by genes also linked to Igh-1b-allotype genes, and the 6036 allotype genes are situated between Ig-VH and prealbumin genes.

Absorption↗

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 epsilon chain. An antiserum raised in BALB/c mice against monoclonal IgE of C57BL/6 origin reacted exclusively with IgE of strains having Igh-1b (IgG2 a) allotype. The second antiserum, C57BL/6 anti-BALB/c monoclonal IgE, reacted with IgE of strains having Igh-1a, Igh-1d, Igh-1e and Igh-1j 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 epsilon chain is controlled by the seventh murine immunoglobulin allotype locus, and should be designated as the Igh-7 allotype.

Alleles↗

Rabbit heavy chain haplotypes--allotypic determinants expressed by VH-CH recombinants.

This report summarizes our current understanding of the heavy chain haplotypes found in our laboratories' rabbits. Independently derived data from several laboratories have been synthesizes into a consistent picture of the linked inheritance of allotypic markers found on the different heavy chain classes and subclasses of rabbit immunoglobulins in pedigreed rabbits, including the families of three apparent VH-CH recombinants. In one recombinant, the entire group of CH markers (C mu, C gamma, and C alpha) recombined with the set of VH. Although in the other two recombinants all CH markers may also have recombined as a group, in one of these only IgG and IgA CH genes were informative; in the other recombinant, only the IgG allotypes were informative. Some allotypic determinants found on IgM molecules ("conformational") appear only when a specific variable region allotype (VHa) is combined with a specific mu constant region allotype (C mu). New combinations of VHa and C mu allotypes were generated in two of the genetic recombinants and led to new "conformational" determinants. The gains and losses observed lend support to the hypothesis that the determinants result from conformations generated by the combination of allotype-specific VH and C mu protein sequences. Conceivably, DNA events that join VH to diversity (D)- and joining (J)-coding sequences or mRNA processing events that splice J to C mu could be involved in generating the sequences that form allotype-specific determinants.

Animals↗

T lymphocytes specific for immunoglobulin allotype. I. Igh-1b-specific T cells demonstrated by suppression in vivo and cytotoxicity in vitro.

We show that determinants of IgG(2a) of C57BL/6 mice (Igh-1(b)) stimulate allotypespecific T cells in BALB/c mice. Such cells are detected in two different functional assays; chronic allotype suppression and T cell-mediated cytotoxicity. A population of suppressor T cells capable of inducing chronic Igh-1(b) suppression was demonstrated by rosetting procedures to possess Igh-1(b)-specific receptors, a result interpreted as indicating that suppressor T cells may act directly upon allotype-bearing B cells. From similar populations we were also able to demonstrate Igh-1(b)-specific cytotoxic T cells. Such cells were lytic for target myeloma cells expressing the Igh-1(b) allotype of IgG28, and were ineffective against a variant cell line failing to express Igh-1(b), and other target cell lines expressing different allotypes or isotypes. The similar specificity of suppressor T cells and cytotoxic T lymphocytes for Igh-1(b) allotype raises the possibility that the target in allotype suppression is a B cell, and that allotype-specific cytotoxic T cells may play some role in regulation of allotype expression in the suppressed state.

Animals↗

Partial amino acid sequence and genetic control of latent a2 allotype induced in rabbits by immunization with anti-a2 antibody.

We have shown that after immunization of homozygous a1 rabbits of the B immunoglobulin (Ig) heavy chain haplotype with anti-a2 antibody (Ab) a population of molecules appears that has all of the serologic characteristics of the a2 allotype. We have now isolated these putative latent a2 molecules, have separated the heavy chains, and after enzymatic deblocking, have determined the first 19 N-terminal amino acids. For all eight allotype-associated residues, these putative latent a2 molecules have the amino acid residues typical of a2 allotype. As expected, the preimmune IgG from this a1a1 rabbit has the amino acids typical of the a1 allotype. Thus by partial amino acid sequence analysis, we provide additional evidence that the latent a2 allotype can be induced in a1a1 rabbits of the B heavy chain haplotype by immunization with anti-a2 Ab. Rabbits of other heavy chain haplotypes were also immunized with anti-a2 Ab and were tested for their ability to synthesize latent a2 allotype. Thus far, a1a1 rabbits of the A, B, C, and I heavy chain haplotypes all synthesize latent a2 allotype. In contrast, a3a3 rabbits of the G and H heavy chain haplotypes did not synthesize latent a2 allotype.

Amino Acid Sequence↗

Genetic polymorphism of IgG in mink. II. A genetic analysis of allotypes.

Population distribution and inheritance pattern were analyzed in mink IgG allotypes: L1 (L chains), H2, H3, H4, H6, H7, and H8 (the constant region of the H chains, i.e. C gamma-allotypes) and conformational allotype 5 with unknown chain localization. Contrary to expectation, neither allelism, nor close linkage were demonstrated for these allotypes. The major feature of the inheritance of H2, H3, and H4 C gamma-allotypes, as well as allotype 5, was significant excess of negative (without these allotypes) progeny in the F1 generation from monohybrid cross. The explanation offered for this departure of the C gamma-allotypes from normal Mendelian genetics suggests widespread latencies of their expression in mink.

Animals↗

Surface immunoglobulin on rabbit lymphoid cells. IV. Ultrastructural labelling of A and B group allotypic determinants.

Equal numbers of rabbit peripheral blood lymphocytes (PBLs) label for either a- or b-group immunoglobulin allotypes using a modification of the mixed antiglobulin reaction of Coombs adapted for electron microscopy. This technique which employs immunoferritin markers is consistently more sensitive than other methods used for labelling surface Ig on lymphocytes. Although approximately 75 per cent of PBLs label for either a- or b-group allotypes, the number of immunoferritin grains on the cell surface after labelling for b group allotypes is nearly twice as great as that observed after labelling for a group allotypes. We conclude that essentially all Ig-bearing blood lymphocytes of the rabbit express both heavy chains (a allotypes) and light chains (b allotypes) on their surface membranes, but that light chain allotypic determinants are more accessible or exposed than the heavy chain (Fd) allotypic determinants.

Animals↗

Control of latent allotype expression by rabbit splenocytes.

Serologic and chemical studies have suggested that immunoglobulin structural genes are under nonallelic genetic control. The transient appearance of unexpected (i.e., latent) allotypes in serum further suggests that cellular control mechanisms may be operative. We report here the results of our efforts to induce the expression of latent allotypes by cultured rabbit splenocytes. The protein A plaque assay facilitated with various anti-allotypic antisera was used to enumerate allotype-specific plaque-forming cells. When splenocytes from a b4 b4 rabbit are cultured in the presence of anti-b4 alloantisera, the number of b4 PFC (i.e., nominal) is suppressed and the number of PFC expressing the latent allotype is increased. The specificity of the induced latent PFC is dependent upon the source and allotypic mosaic of the antiserum added to the cultures. Our results suggest that lymphocytes committed to latent allotypes are normally suppressed. Activation by the appropriate alloantiserum directed against the nominal allotype may relieve a cell-mediated suppressive mechanism.

Animals↗

Serum Gm allotype levels in common variable immunodeficiency: preponderance of homozygous G2m(",") on IGHCG2.

Common variable immunodeficiency (CVI) is one of the most frequent primary immunodeficiency diseases, characterized by defective antibody formation and associated with chronic sinopulmonary infections, autoimmunity and malignancies. The genes for the constant heavy chains of IgG are located on chromosome 14 and were further studied by identifying allelic, alternative Gm allotypes. These were defined by different epitopes for three of the IgG subclasses, G1m(a) and G1m(f) for IgG1, G2m(n) and G2m(") for IgG2 and G3m(g) and G3m(b) for IgG3. A sensitive competitive ELISA method for quantitation of the Gm allotypes G1m(a), G1m(f), G2m(n) and G3m(b) were used together with radial immunodiffusion IgG subclass quantitation. The dominating number of 25 of 33 patients (p < 0.001) expressed the homozygous G2m(",") allotype on IGHCG2 in combination with homozygous or heterozygous Gm allotypes on IGHCG1 and IGHCG3, namely Gm(f,f;",";b,b), Gm(a,a;",";g,g) and Gm(f,a;",";b,g). Studies of Gm allotype quantities revealed a progressive sequential impediment of the programmed cascade for downstream IGHCG gene rearrangements. According to the order of the IGHCG genes, the G3m allotype levels from the IGHCG3 were often normal, and G1m allotype levels from IGHCG1 were suppressed; G1m(a) was suppressed more than G1m(f), and most suppressed were G2m allotype levels from IGHCG2, both G2m(n) and G2m("). The susceptibility of CVI is associated to G2m(",") expression from the IGHCG2 locus on chromosome 14, which has also been found in IgA IgG subclass deficiency, conditions known among first-degree relatives.

Adult↗