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At least 19 recordsLinked to original sources
PubMed1978

Regulation of allotype expression in heterozygous rabbits. II. Concomitant suppression of b4 and b6 allotypes in the same cell.

Cells from heterozygous b4b6 rabbits were treated at 4 degrees with anti-b4 or anti-b6 antibodies and then warmed at 37 degrees. A disappearance of both b4 and b6 allotypes (concomitant modulation) ensued. When cells which had undergone extensive comodulation were cultured overnight we noted that those cells were unable to re-express either allotype at pre-modulation levels. This suppression was likely linked to the initial events which culminated in comodulation. Those cells were not further suppressible when suppressive antibodies were added to the cultures whereas cell cultures which had undergone little or no previous modulation or comodulation were readily suppressed for both allotypes after anti-allotype antibodies had been added to the cultures overnight (concomitant suppression). This indicated that in vitro suppression of allotype may depend on cell surface allotype being present at a sufficiently high density. We present data which show that events at the cell surface may play a role in the regulation of cell surface allotype expression and propose that concomitant suppression may have bearing on cellular mechanisms which control allotype expression and also allotype suppression.

Animals↗
PubMed1978

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.

Animals↗
PubMed1978

Structural and genetic studies on chicken 7S immunoglobulin allotypes. IV. The presence of an unexpected chicken immunoglobulin heavy chain allotype: subclass or pseudoallele?

Low concentrations of allotypic specificity CS-1.1 were detected in the sera of two inbred chicken lines [University of California, Davis (UCD) 7 and Regional Poultry Research Laboratory 15I4] previously reported to lack this specificity. The CS-1.1 alloantigen in 15I4 chickens has the same specificity as the major allotype in a line of chickens (UCD 2) in which it was initially defined. In 15I4 chickens, CS-1.1 allotype is present on a population of molecules distinct from those which carry the major allotype; thus a second 7S Ig H chain locus, CS-2, is proposed. The concentration of CS-1.1-bearing molecules determined by two different methods was 7 microgram/ml and 230 microgram/ml in 15I4, whereas UCD 2 chickens had 4 mg/ml of CS-1.1 molecules. The levels of CS-1.1 inhibitory activity in 15I4 birds remained relatively constant over a 30-day period. The presence of two 7S Ig populations in 15I4 chickens may be interpreted as evidence either for 7S Ig subclasses with shared allotypes or for a pseudoallelic organization of genes controlling expression of 7S Ig H chains. The results were consistent with the presence of redundant C region genes, differing in allotypes, whose expression is under the control of an as yet undefined regulatory mechanism.

Alleles↗
PubMed1977

Regulation of allotype expression in heterozygous rabbits. III. Concomitant modulation and concomitant suppression oa a2 and a3 allotypes on individual peripheral blood lymphocytes.

Sensitization of peripheral blood lymphocytes from heterozygous a2/a3 rabbits with purified, monospecific anti-a3 antibodies, raised in a1/a1 rabbits, resulted in the disappearance of surface a2 and a3 allotypes (concomitant modulation) after subsequent incubation at 37 degrees C, as determined by the mixed antiglobulin (rosette) test. Similar results were obtained when anti-a2 antibodies were used. The dose dependence of modulation and comodulation were also studied. Testing of mixtures of homozygous a2/a2 plus a3/a3 cells never led to comodulation. Blocking studies, performed to determine the surface contiguity of a2 and a3 determinants, indicated that both allotypes are situated close together in the membrane on cells exhibiting allotype inclusion. Overnight culture in serum-free medium revealed that cells which underwent extensive modulation and comodulation were often suppressed for both homologous and alternate allotypes (concomitant suppression). These and other data suggest that a single modulation event, in which extensive removal of cell membrane Ig occurred, could serve to inhibit the re-expression of Ig. This may, in part, reflect interactions with membrane receptors involved in the regulation of expression of VH gene products. Implications of VH allotype inclusion are discussed.

Animals↗
PubMed1975

In vitro studies on allotype suppression. III. compounds of antiallyotype serum active in release from allotype suppression.

Spleen cells of b4b6 rabbits, shown to be deficient in their ability to produce b4Ig due to prenatal exposure to anti-b4, formed anti-T2 antibodies marked with the b4 determinant in response to solubilized T2 phage (S-T2) only when cultured in the presence of antibodies specific for the nonsuppressed type (b6), thus confirming and extending the previously reported observation of release from b4 suppression in cultured cells of b4-suppressed b4b5 rabbits treated with anti-b5 serum. Only antiallotype sera made in b4 rabbits were active in reversing b4 suppression. Anti-b5 or anti-b6 sera from rabbits of allotypes b6 or b5, respectively, when used in concentrations which completely or partially inhibited the formation of anti-T2 antibodies marked with the corresponding nonsuppressed allotype of the spleen donor, proved to be almost completely ineffective in causing release of suppression. Exceptions were noted when spleen cells of rabbits advanced in spontaneous escape from suppression were tested with such sera. The addition of normal b4 serum to non-b4 antiallotypic sera rendered them as effective in releasing b4 suppression in vitro as were antisera from b4 rabbits. Furthermore, the capacity of a b4 antiallotype serum to cause reversal of b4 suppression could be potentiated by the addition of normal b4 serum, indicating that nonantibody b4 Ig is a limiting factor in such a serum. Thus, the release from allotype suppression observed in cultures of spleen cells from b4-suppressed heterozygous rabbits is dependent upon the presence of two components: antibodies directed against the nonsuppressed allotype of the donor and normal b4Ig. These findings are interpreted in terms of alternate hypotheses involving (a) a mechanism of b4 derepression and (b) inactivation of a suppressor cell with recognition for a b4-labeled target.

Animals↗
PubMed1977

Allotype suppression in rabbits: the requirement for CH3 domain of anti-allotype antibody.

Facb fragments of rabbit anti-allotype antibody were prepared by plasmin digestion and isolated by gel chromatography. The antibody preparation was used in an attempt to induce allotype suppression in newborn rabbits. The Facb fragments were found to be ineffective in inducing the allotype suppression. Administration of Facb fragments caused a "burst" of immunoglobulin synthesis almost immediately after the administration of the antibody. It was concluded that the CH3 domain, which is responsible for the cytophilic activity of the antibody, is essential in induction of allotype suppression.

Animals↗
PubMed1976

Synchronous regulation of VH and CH allotypes among Ig molecules in multi-heterozygous rabbits suppressed with anti-VH allotype antibody: emergence of IgA from suppression prior to IgG and IgM.

Heterozygous rabbits of genotype a1n81f73g74/a2n82f71g75 were suppressed at birth for the VH region a1 allotype. At 8 weeks of age, quantitative analysis of serum IgG, IgM, and IgA molecules showed that the VHa1 specificity was effectively suppressed in the three classes of Ig and that the suppression was extended to the CH region n81 specificity on mu-chains as well as to the CH region f73 and g74 specificities on alphaf and alphag chains. At 26 weeks of age, analysis of serum IgG and IgM molecules showed that a1 was still suppressed to approximately the same extent in both Ig classes and the suppression was still extended to the CH region n81 specificity. However, at 26 weeks, the percentage of molecules with a1 specificity had doubled among serum and colostral IgA molecules and this increase was extended to the CH region f73 and g74 specificities. Thus, the suppressed allotypes reappeared first among IgA molecules. Our data are consistent with a regulatory mechanism which controls and synchronizes the expression of the VHa and the CH allotypes expressed on the same heavy chain. The order of the re-expression of the suppressed allotypes with respect to Ig class may allow further definition of selective regulatory mechanisms for the synthesis of Ig classes.

Animals↗
PubMed1978

Regulation of allotype expression in heterozygous rabbits. I. Concomitant modulation of cell surface allotypes on peripheral blood lymphocytes from b4b6 rabbits.

Treatment of b4b6 rabbit peripheral blood lymphocytes with b5b5 anti-b4 antibodies at 4 degrees resulted in the modulation (disappearance) ob b4 and b6 cell surface allotype after subsequent incubation in serum-free medium for 1 h at 37 degrees. A clear dose dependence on the sensitizing anti-b4 antibody was observed. Similarly, b5b5 anti-b6 treatment demonstrated a dose dependence for b6 modulation and a threshold dose effect for b4 comodulation. Cells which formed rosettes with anti-b4-coupled SRBC (anti-b4 direct antiglobulin (DAG) rosettes) also demonstrated concomitant modulation of b4 and b6 allotype when incubated at 37 degrees. When cells formed anti-b6 DAG rosettes, subsequent b6 modulation could also be demonstrated, but no b4 comodulation occurred. Concomitant modulation did not occur when cells were incubated with anti-allotype antibodies at 37 degrees. Blocking studies disclosed that the two allotypes are not contiguous in the membrane since uptake of one antiallotype antibody did not block the uptake of another at 4 degrees. We therefore propose that concomitant modulation might occur during a process similar to patch formation.

Animals↗
PubMed1977

Structural and genetic studies on chicken 7S immunoglobulin allotypes. II. Distribution of allotypes on the 7S immunoglobulin of homozygous and heterozygous chickens.

We have previously reported that chicken 7S immunoglobulin (Ig) heavy (H) chain allotypes (CS-1 locus) segregate as phenogroups in F2 progeny. Specificity CS-1.1 formed a phenogroup with CS-1.4 in inbred chicken line UCD 2, and a second phenogroup with CS-1.3 in line UCD 3. To determine whether these phenogroups were formed by combinations of specificities on the same, or on separate subclasses of 7S Ig, their distribution on the 7S Ig molecules of birds homozygous for 7S Ig allotypes was analyzed by radioimmunoassay. Anti-CS-1.1 and anti-CS-1.3 alloantisera each bound more than 94% of line UCD 3 1252-7S Ig. Similar results were obtained with alloantisera to CS-1.1 and CS-1.4 WITH 125 I-7S Ig from line UCD 2. These results indicate that both phenogroups were formed by combinations of specificities present on the same H chain. Thus, each phenogroup described, probably is the product of a single structural gene which is responsible for more than 94% of the 7S Ig H chain constant regions. In F hybrids with the genotype CS-1.3, 1.3/CS-1.2, two populations of serum 7S Ig molecules were detected by direct and sequential binding analysis with specific alloantisera. One population of 7S Ig contained specificities CS-1.1 AND CS-1.3, but not CS-1.2; while the second population was exclusively the product of one parental allele. Consistent with a genetic regulatory mechanism involving allelic exclusion, no MS Ig containing allotypes produced by both alleles was detected.

Animals↗
PubMed1977

Human IgG3 allotypes, with special reference to a new allotype related to G3m(g) (G3m21).

The IgG3 allotype described as L1 (Blanc et al., 1976) occurs on the CH3 region of G3m(g) proteins, in contrast to G3m(g) that is known to be present on the CH2 region. G3m(g) and L1 are, as a rule, present on the same gamma3 heavy chain, just like the G3m(b) subspecificities of the CH2 region, (b1) and (b4), with those of the CH3 region (b0), (b3) and (b5). Several families were investigated that showed inheritance of rare combinations of IgG3 allotypes. The data obtained are suggestive for notation of L1 as (g5), since L1 probably occupies a position antithetical to (b5). The relation of amino acid substitutions to allotypes and isoallotypes is discussed.

Alleles↗
PubMed1978

In vitro studies on allotype suppression. IV. Abrogation of waning suppression by normal immunoglobulin of the suppressed allotype.

The mechanism of allotype suppression in rabbits has been investigated by studying the in vitro immune responses of spleen cells from rabbits in advanced stages of spontaneous recovery from suppression. Whereas the spleen cells from highly suppressed rabbits can be released from their suppressed state only if treated with a combination of antibodies against the non-suppressed type and immunoglobulin (Ig) of the suppressed type, treatment with either of these two components alone suffices to overcome suppression when cells of more poorly suppressed spleen donors are used. The demonstration that suppression can be abrogated by normal Ig of the suppressed type alone, when cells are obtained from rabbits in the final phases of suppression, lends further support to the previously suggested concept that the probable role of this normal Ig in the release phenomenon may be that of neutralizing an effector of allotype-specific repression, possibly involving suppressor cells.

Animals↗
PubMed1976

Studies on the structural localization of rabbit H chain allotypic determinants controlled by the a locus. Purification and immunological properties of an immunopeptide bearing a3 allotypic determinants.

An immunopeptide bearing a3 allotypic determinant(s) was isolated from the gamma chain of an a3 homozygous rabbit (G222-2) immunized with type III pneumococcal vaccine. Immunocogical properties of peptides were studied using a radioimmunoassay that involved inhibition by these peptides of a reaction between 125I-labeled anti-a3 antibody and Sepharose-bound a3 immunoglobulin G (IgG). The gamma chain was isolated from IgG of restricted heterogeneity and then citraconylated and digested with trypsin. The tryptic digest (TD1) was passed through an anti-a3 immunoabsorbent column either directly or after an intermediate step of Sephadex G-75 chromatography. The bound peptides (T1) were eluted with 0.1 M acetic acid and further digested with trypsin. The digest (TD2) was again run on the anti-a3 immunoabsorbent column to purify the bound immunopeptide T2. In the radioimmunossay this immunopeptide was found to have major a3 determinant(s). Its molecular weight was found to be approximately 6,000, which decreased to about 3,000 after reduction and alkylation. These data, together with NH2- and COOH-terminal analyses and cysteine peptide mapping, demonstrated that T2 is composed of two polypeptide chains linked by a disulfide bond, one from the cysteine 22 region having lysine at the COOH terminus and the other from the cysteine 92 region arginine at the COOH terminus. The lysine peptide was separated from the arginine peptide and its NH2-terminal sequence was found to be Gly-Asx-Glx-Ser-Thr-Cys. Since the cysteine is at position 22, the lysine peptide starts at position 17. It has approximately 22 residues. The framework sequence from 17 to 20 is different from those reported so far. In addition, the heavy chain used in these studies has some other unusual features including a histidine, probably in the first hypervariable region. The presence of histidine in the first hypervariable region of rabbit heavy chain has not been reported previously. The other peptide which is about 30 amino acids in length and ends with arginine 94, probably includes positions 67, 70, 71, 84, and 85 that are believed to have substitutions correlating with a allotypes. In a hypothetical three-deminsional model of the Fv portion of rabbit anti-SIII antibody BS-5, residues 17 to 33 of the lysine peptide and 67 to 79 and 84 to 85 which may be present in the arginine peptide are fully exposed on the surface and are far removed from the antibody combining site.

Amino Acids↗
PubMed1975

In vitro studies on allotype suppression. II. Regulation of antibody synthesis by anti-allotype serum.

The regulatory effects of rabbit antibodies specific for light chain determinants (b locus) on the formation of rabbit serum immunoglobulins have been studied in an in vitro system which measures of the response of unprimed rabbit spleen cells to solubilized T2 phage antigen. Treatment of spleen cells from b4b4 rabbits with anti-b4 serum, which was either incorporated into the culture medium or employed in appropriate pulse treatment of the cells before culture, prevented the formation of T2 neutralizing antibodies by such cells. Spleen cells of heterozygous (b4b5) rabbits formed anti-T2 antibodies which could be shown to be divided between the b4 and b5 specificities. Incorporation of anti-b4 or anti-b5 serum into the culture medium suppressed the specific anti-T2 response and, except in the instances noted in the text, did not significantly change the level of T2 neutralizing antibodies marked with the alternate allelic determinant. These findings are discussed in the light of the compensatory formation of an alternate immunoglobulin type which occurs during allotype suppression in vivo.

Animals↗