Age Variation of the Phenotypic Expression and the Inheritance of the IgG System of Immunoglobulin Allotypes in the Pig

The specificity of phenotypic expression and inheritance of immunoglobulin allotypes IgG1a and IgG2b in piglets are discussed. It was shown that a negative state by both these allotypes is repeatedly found among newborn piglets but is extremely rare in pigs older than one month. A model, which simultaneously describes the genetic determination of allogroups formed by allotypes IgG1a and IgG2b and the dynamics of ontogenetic expression of individual genotype by systemIgG with a result of a visually registered phenotype, was developed. Allele frequencies by system IgG were assessed in populations of domestic pigs of commercial breeds, laboratory miniature pigs, and Eurasian wild boar.     

Immunogenetic study of porcine IgG

Three allotypes of IgG were identified in pig. Based on data obtained on electrophoretic mobility as well as on results of the International Comparative Test ISABR for pig blood group, polymorphic proteins and enzymes (1987-1988), the allotypes are specified as markers of two different IgG subclasses and are referred to as IgG1a, IgG2b and IgG2c. The former of these is established as corresponding to the already known IGH3 C1, and the other two had not been earlier described. In herds of pigs being bred in the Georgian SSR, the IgG1a allotype frequencies in Kakhetinskaya, Large White, Landrase and Lithuanian white were 0.84, 0.93, 0.91 and 0.94, respectively, whereas for the IgG2b allotype it ran 0.89, 0.73, 0.79, and 0.69 in the order mentioned. The IgG2c allotype was not registered in samples under examination.     

Tritrichomonas foetus extracellular cysteine proteinase cleavage of bovine IgG2 allotypes

Bovine trichomoniasis is a sexually transmitted disease associated with reproductive failure. Systemic immunization results in protective IgG antibodies in uterine and vaginal secretions. Because bovine IgG2 is a better opsonin than IgG1, it is potentially important in defense. Yet, Tritrichomonas foetus extracellular cysteine proteinase (TFECP) cleaves bovine IgG2, evading protective IgG2 responses. Variations in resistance of the 2 IgG2 allotypes to digestion may explain inherited differences in protection. To address this hypothesis, TFECP was incubated with both IgG2 allotypes at different concentrations and times. The digestion products were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis, stained, and quantitated by image analysis. IgG2a was digested faster by TFECP than IgG2b. Differences in the sizes and numbers of digestion products were observed, but the presence of bands the size of Fc and Fd fragments indicated that both allotypes were cleaved at the hinge. Cysteine in the digestion mixture reduced the antibody molecules and increased the rate of digestion, but IgG2a was still more susceptible to cleavage than IgG2b in the absence of cysteine. Thus, not only reduced H chains can be cleaved by cysteine proteinase secreted by T. foetus but also intact functional antibody molecules. Because parasites may evade protective antibody responses by cleaving IgG2, animals with the more resistant IgG2b allotype may be better protected by immunization than animals with the more readily digested IgG2a allotype.     

Characterization of Chicken B-Locus (Igg) Allotypes

Chicken allotypes b1 and b2 are controlled by allelic genes and associated with the IgG class of immunoglobulins. The determinants cannot be detected on either isolated heavy and light polypeptide chains or the enzymatic fragments. The results suggest that either the intact IgG molecule is required for their expression or the conditions normally used for isolation of the subunits destroy or modify the antigenic specificities in chickens.     

Surface immunoglobulin on rabbit lymphoid cells. III. Double expression and separate endocytosis of surface immunoglobulin allotypes on heterozygous lymphocytes demonstrated by immunoelectron microscopic labeling.

The expression of immunoglobulin b locus (k chain) allotypes on the surface of rabbit peripheral blood lymphocytes (PBL's) is examined using an indirect double immunoelectron microscopic labeling technique. Ferritin and whelk hemocyanin individually conjugated to allotypically specific IgG are used as ultrastructurally identifiable molecular markers. These indicators are coupled to lymphocyte surface immunoglobulin (Ig) allotypic determinants by an antiallotype antibody linkage. Human red blood cells, conjugated with IgG of a specific allotype and used as test cells, demonstrate the absolute specificity and high efficiency of the ultrastructural labeling technique. Specific labeling on rabbit PBL's shows that 65–75% of the cells are positive for surface Ig. Lymphocytes from homozygous donors (b4b4 or b6b6) are labeled specifically with only the appropriate allotypic labeling system. Thirty-three percent of the PBL's from heterozygous donors (b4b6) express both allotypes (allelic inclusion) on the cell surface; the remaining proportion of Ig-bearing cells have only one detectable allotype present (allelic exclusion). We conclude that approximately 50% of the Ig-bearing PBL's demonstrate allelic inclusion for the b locus allotypes. On allelically included heterozygous lymphocytes, both allotypic determinants can undergo specific endocytosis. Endocytosis of one allotype on heterozygous cells can be induced by stimulation with antiallotypic serum without affecting the surface appearance of the other allelic marker (separate endocytosis).     

A2G--a new system of alpha-2-globulin allotypes in pig blood serum]

Combinations of four alpha-2-globulin allotypes were studied for their distribution in pigs of nine different breeds and hybrid groups. Based on this analysis, a new, previously unpublished polyallelic genetic system designated A2G was postulated. The complex alleles of this system control alpha-2-globulin allotypes and are suggested to be encoded by genes of two subloci. One of these subloci is virtually monomorphic, whereas the other has at least four allelic variants.     

Immunoglobulin allotypes (Gm,Am, and Km) in non-human primates

The immunoglobulin (Ig) allotypes (Gm, Am, and Km systems) are the genetic markers of the human IgG1, IgG2, IgG3(Gm), IgA2(Am), and kappa light chain(Km). The Gm system, with 18 allotypes shows the greatest degree of polymorphism and we define two Am and three Km allotypes. In this review, we report all the results observed in non-human primates belonging to Hominoidea, Cercopithecoidea, Ceboidea, Lorisoidea, Lemuroidea, and Tupaoidea superfamilies (72 species and subspecies). They concern published data and new unpublished ones. The distribution of the human allotypes and their localization are reported, as well as discordant results observed in some cases with anti-allotype reagents of the same specificity (human and animal origin). Some allotypes are restricted to man. Hominoidea have the greatest number of Gm allotypes and the richest polymorphism. Relatively few allotypes have been found in Cercopithecoidea and Prosimians; most Platyrrhinian species have no allotype. The epitopic polymorphism has been interpreted in terms of evolution of Ig allotypes from primate to man and of the phylogenetic relationships of non-human primate species.     

Immunogenetic Polymorphism of Lipoproteins in Swine: Genetic, Immunological and Physiochemical Characterization of the Two Allotypes Lpr1 and Lpr2

Results of immunogenetic, immunochemical and physicochemical investigations on two serum allotypes of swine are reported. The allotypes, designated Lpr1 and Lpr2, have been identified by specific alloprecipitins in agar gel. Genetic studies indicate that the allotypes are specified by two codominant autosomal allelic genes, Lpr1 and Lpr2. All pigs 3 months of age or older were classified as belonging to one of three phenotypes, Lpr1, Lpr2 or Lpr1,2, each corresponding to one of three genotypes Lpr1/1, Lpr2/2 or Lpr1/2, respectively. The Lpr1 gene was absent or was found at low frequency in the breeds tested. The allotypes were found to occur in two physicochemical forms; in association with chylomicrons and very low density lipoproteins (VLDL) and, primarily, as a Lpr multimer free of the major lipoproteins showing very high density (VHD), d greater than 1.21 g/ml, and MW +/- 190,000. Gel-electrophoretic mobility for VHD-Lpr is different for each of the three Lpr genotypes residing in gamma-fast and beta-slow regions, but is identical for VLD-Lpr in which Lpr was found complexed with apo-B, migrating as VLDL in the alpha-2 slow (pre-beta) region. Serum levels of Lpr varied during the lifetime and between individuals and, especially, between sera of homozygous pigs being higher in Lpr1/1 than Lpr2/2. A linear relationship for Lpr1 and an atypical, inverse relationship for Lpr2 have been observed between the gene dosage, heterozygous vs. homozygous, and the Lpr serum level.     

The contrasting IgG-binding interactions of human and herpes simplex virus Fc receptors

A virally encoded, high-affinity Fc receptor (FcR) is found on herpes simplex virus type 1 (HSV-1) particles and infected cells where its binding of non-immune IgG protects cells from host-mediated lysis. Whilst mutation or aglycosylation of the IgG CH2 domain reduced binding to human FcR, the interaction with HSV-1 FcR was not affected. However, the HSV-1 FcR, unlike human FcR, discriminates between human IgG1 allotypes, being sensitive to changes at positions 214 (CH1) and 356/358 (CH3), away from its proposed binding site at the CH2-CH3 interface. The biological consequences are not known but this is the first evidence of a major functional difference between IgG1 allotypes.     

Rabbit latent group a allotypes: characterization and relationship to nominal group a allotypic specificities.

Latent group a allotypes were detected with a sensitive radioimmune inhibition assay. Sera, IgG preparations, and antibody fractions containing these allotypes inhibited the binding of insolubilized allotypic antisera to various radiolabeled antigens including IgG pools, homogeneous antibodies, and, in the case of a3, a VH fragment from a3/b4 IgG. Several different group a antiallotypic sera were used in the assays and all gave similar results. Comparison of inhibition curves for nominal and latent allotypes indicated that the full spectrum of allotypic subspecificities may be expressed in latent allotypes. Hemagglutination studies carried out with five sera containing high levels of latent allotypes confirmed the results obtained with the radioimmunoassay and indicated that inhibition values did not, at least in four of the five samples studied, reflect the presence of antiallotype antibodies.     

Ig allotype-linked regulation of class and subclass composition of natural antibodies to group A streptococcal carbohydrate

To determine the importance of genes located in or near the Ig constant regions in regulating the human antibody response, we correlated Ig allotypic markers with total Ig concentrations and natural antibody concentrations to the streptococcal group A carbohydrate (A-CHO) in 193 healthy adult blood donors. The major correlations between Ig allotypes and total Ig and specific antibody concentrations were observed with the Gm(f;n;b) haplotype. When compared with Gm(f;n;b) negative individuals, Gm(f;n;b) positives had significantly higher concentrations of total IgG2 (p less than 0.001) and IgG2 anti A-CHO (p less than 0.05), lower concentrations of total IgG1 (p less than 0.001) and IgG1 anti A-CHO (p less than 0.001), and lower concentrations of total IgM (p less than 0.001) and IgM anti A-CHO (p less than 0.05). We conclude that individuals with the Gm(f;n;b) haplotype respond preferentially with IgG2 rather than IgG1 subclass antibodies. This increased capacity to respond with IgG2 antibodies may be reflected in the magnitude of the total antibody response when the IgG2 subclass comprises a major proportion of the response, as occurs in the adult response to many polysaccharide Ag.     

Homology between the Lpm system of allotypes in the American mink and the Gp system of allotypes in the domestic pig]

The 5 alpha-macroglobulin allotypes alpha M1, alpha M2, alpha M3, alpha M4 and alpha M5 were identified in pig. The alpha M1 allotype was reported as a marker of pig alpha-macroglobulin, the latter being homologous to alpha 2-macroglobulins in human and in mink. The allotypes alpha M2-alpha M5 were specified as markers of the second isotypical variant of pig alpha-macroglobulins, which was homologous to mink Lpm macroglobulin (alpha 1M). As seen from data obtained by International Comparative Test ISABR 87-88, alpha M1 is a new allotype, while allotypes alpha M2--alpha M5 correspond to four allotypes in the Gp system (Janik et al.). Based on these data, a conclusion was made on the homology between the Lpm system in american mink and the Gp system in pig. Since the allotypes studied are the part of alpha-macroglobulins, a locus controlling them was designated the AM locus. We also find it more advantageous to apply the same name to the homologous locus in mink, instead of the Lpm used earlier. Genetic control of 5 allotypes was studied and the structure of the AM locus in pig analysed in detail. Comparative study of organization of the above locus and the homologous locus in mink was carried out.     

Analyses of the splenic mRNA expressed by rabbits of different immunoglobulin kappa-light chain allotypes: conserved sequences in the 3' untranslated region and allotype-specific probes

The allelism of the structural genes for the complex rabbit b allotypes of immunoglobulin kappa-light chains has been questioned because of observations of unexpected phenotypic expression of "latent" allotypes. We find that the coding sequences of the b4 and b5 "alleles" are only 80% homologous for the last 60 nucleotides but there is a high degree of homology (96%) in the 3' untranslated region (3'DT). The high conservation of 3' DT region sequences enabled us to detect kappa-light chain mRNAs from rabbits of different genetic types (b4, b5, b9 and bbas) on northern blots and dot blots. We can distinguish mRNA encoding b9 and b5 allotypes on dot blots with b5 fragment-probes of known sequence and detect mRNA produced by unstimulated cultured splenic lymphocytes. Analyses of mRNA from cultured cells manipulated to enhance mRNA synthesis and production of unexpected or "latent" b allotypes can now be conducted.     

Allotype-related sequence variation of the heavy chain of rabbit immunoglobulin G

The heavy chain of rabbit immunoglobulin G exists in three major allotypic patterns, Aa1–Aa3. A comparison of the amino acid compositions of the heavy chains isolated from immunoglobulin IgG homozygous for each allotypic determinant revealed the presence of an additional methionine residue per chain in the Aa3 allotype relative to the Aa1 and Aa2 allotypes. The position of the additional methionine residue was determined by cyanogen bromide cleavage and by tryptic digestion of the γ-chains; it coincided with the inter-Fd–Fc area of the chain. Isolation and characterization of the corresponding tryptic peptides of 31 amino acid residues from each of the allotypes showed the presence of a methionine-for-threonine replacement in the Aa3 allotype, but only in about 70–80% of the molecules. No other allotypic variations were seen in this tryptic peptide. Allotypically related variations in composition were also detected in the N-terminal cyanogen bromide-cleavage peptide.     

Immune events associated with high level protection against Schistosoma japonicum infection in pigs immunized with UV-attenuated cercariae

Background

The vaccination of radiation-attenuated Schistosoma japonicum cercariae can induce effective protection in artiodactyl, but the immune events related to protective immunity are not fully understood. To provide a paradigm for a human recombinant antigen vaccine, we have undertaken a vaccination and challenge experiment in pigs, which was recognized as an appropriate animal model in this type of study because of their similarity to human in immunology, and investigated the relative immune events induced by the radiation-attenuated S. japonicum cercariae.

Methods and Findings

We found that pigs immunized once with 400 µw UV-irradiated cercariae exhibited 63.84% and 71.82% reductions in worm burden and hepatic eggs respectively. Protective immunity in vaccinated pigs was associated with high level productions of IgM, total IgG, IgG1 and IgG2; IgG2 was significantly increased in the acute infection. IFN-γ levels could be elicited by immunization. At week 6 post-infection, IFN-γ, IL-4 and IL-10 levels also showed a dramatic rise synchronously in vaccinated pigs. Moreover, the granzyme b, nk-lysin, ifnγ, il4 and il10 mRNA levels in early skin-draining lymph nodes of immunized pigs were higher than those in pigs with non-irradiated cercariae infection. In addition, cytotoxicity-related genes in the mesenteric lymph nodes were significantly upregulated in vaccinated pigs in the acute infection.

Conclusion/Significance

Our results demonstrated that IFN-γ and IgG2 antibody production, as well as genes related to cytotoxicity are associated with the high level protection induced by UV-irradiated Schistosoma japonicum vaccine. These findings indicated that optimal vaccination against S. japonicum required the induction of IFN-γ, IgG2 antibody related to Th1 responses and cytotoxicity effect.     

A fourth heavy chain variable region subgroup, w, with 2 variants defined by an induced auto-antiserum in the rabbit

An antiserum recognizing previously undescribed antigenic determinants (designated subgroup w) of the heavy chain VH region was produced by immunizing a rabbit, homozygous for the VH haplotype a1x-y- with IgG from another a1x-y- rabbit, suppressed for a1. The antiserum gives a single fused precipitin band against sera from homozygous rabbits suppressed for the a1, a2, or a3 allotypes. By gel diffusion analysis, the determinant was found to be distinct from previously described a, x, and y allotypes, and was detectable on IgG, F(ab')2 gamma and the gamma-heavy chain. Radioinhibition analysis revealed 2 patterns of inhibition suggesting 2 variants of w that are closely linked to VH allotypes. Variant w34 was detected at very low levels (0.042 to 5.6 micrograms/mg IgG) in normal rabbits expressing the a1x-y-, a1-y33,30, and a3x32y- VH haplotypes. Variant w35 was detectable in a 2x32y33,- rabbits. Sera from homozygous a allotype-suppressed rabbits representing each of the 4 VH haplotypes similarly exhibited either w34 or w35 patterns of inhibition as described above. The level of w34 in a1- and a3-suppressed rabbits exhibited a dramatic 230-fold median increase. In contrast, w35 levels for a2-suppressed rabbits fell within the normal range. In addition to reacting with essentially all normal and suppressed sera, the antiserum reacted with preimmune serum from the same rabbit. Thus, anti-w represents an induced auto-antibody. These observations are further discussed with regard to rabbit and mouse VH populations.     

5-Azacytidine treatment of a murine cytotoxic T cell line alters interferon-gamma gene induction by interleukin 2

Genetic susceptibility to multiple sclerosis (MS) in Caucasians was previously shown to be correlated to the presence of given alleles at the HLA-DR and Gm loci. We now demonstrate that the humoral immune response in MS central nervous system (CNS) is modulated by both loci: the levels of IgG1 subclass and IgG1 allotypes in cerebrospinal fluid of MS patients depend on both their Gm genotype and their HLA-DR2 or HLA-DR7 phenotype. That HLA-DR molecules may either participate in a preferential recruitment of IgG1 allotype-producing B cells in MS CNS or act after such a selective homing is discussed. These results demonstrate that both HLA and Gm loci are synergistically involved in the modulation of the humoral immune response.     

Allotype suppression in the chicken. V. Abnormal isotype ratios of chronically suppressed IgM and IgG allotypes

Chronic allotype suppression was generated in M-1 (C mu), G-1 (C gamma) heterozygous B14 line chickens either by embryonal injection or by maternal transfer of anti-M-1b allotype antibodies. Using a sensitive radioimmunoassay to detect the suppressed IgM-1b, a striking disparity was observed between the degree of suppression of the IgM-1b allotype and that of the genetically linked IgG-1i allotype. The amount of suppressed IgM-1b ranged between 0.2 and 3% of total serum IgM in chronically suppressed birds. The levels of the genetically linked IgG-1i, however, comprised 5 to 25% of total serum IgG in such birds. The allotypes measured in suppressed chickens were qualitatively identical to those in normal, nonsuppressed birds by serological criteria. These results are discussed within the context of isotype regulation in the chicken.