QUANTITATIVE INVESTIGATIONS OF IDIOTYPIC ANTIBODIES : III. PERSISTENCE AND VARIATIONS OF IDIOTYPIC SPECIFICITIES DURING THE COURSE OF IMMUNIZATION

Changes and persistence of idiotypic specificities of specifically purified rabbit anti-p-azobenzoate antibodies were studied by quantitative methods. In each rabbit idiotypes identified 2 months after the start of immunization were still present in comparable concentrations 2 months later. After month 4, they were replaced by new and unrelated specificities; the changes were abrupt in two rabbits and gradual in the third, and were associated with an increase in the average affinity for specific hapten. In two surviving rabbits the new sets of specificities persisted in part for at least 1 yr. Quantitative changes occurred during this period, and the antibody preparation used as immunogen reacted most effectively with the homologous anti-D serum. The antibody population present at month 17 (D₁₇) in one rabbit was deficient in idiotypic specificities present in D₈ and lacked specificities present in D₂, indicating the presence in D₁₇ of a third group of specificities. The percentage of the antibody population from each rabbit reactive with homologous anti-idiotypic serum was greater at month 8 than at month 2, suggesting a decrease in heterogeneity. Since the donor rabbits were challenged repeatedly with antigen, it appears that, after month 8, a portion of the antigen was utilized to stimulate existing cell lines and a portion to initiate new clones. Precipitation of anti-p-azobenzoate antibodies removed idiotypic specificities, indicating that they were not present on the anti-bovine γ-globulin antibodies in the same sera.     

REQUIREMENTS FOR PROLONGED SUPPRESSION OF AN IDIOTYPIC SPECIFICITY IN ADULT MICE

The appearance of an idiotypic specificity, present in anti-p-azophenylarsonate (anti-Ar) antibodies of all immunized A/J mice, ran be suppressed in adult mice by prior administration of an IgG fraction of rabbit antiidiotypic (anti-D) antiserum; anti-Ar antibodies arise but are of different idiotype. Prolonged suppression was observed in earlier experiments, but antigen was first administered to adult mice only 2 wk or 9 wk after anti-D antibodies; subsequent escape from idiotypic suppression could have been masked by the capture of antigen by large numbers of memory cells having receptors of a different idiotype. In the present experiments antigen was first administered at intervals up to 22 wk after the antiidiotypic antibody. Suppression was maintained for 6 wk in all mice and for 5 mo in about half the mice tested. It thus appears that suppression of idiotype is less reversible if antigen is administered soon after the antiidiotypic antibody. The data suggest that escape from suppression is attributable to the generation of new precursor cells rather than to reactivation of suppressed cells. The minimum dosage of antiidiotypic IgG required for effective suppression was about 2 mg. The subcutaneous or intraperitoneal routes of inoculation of antiidiotypic IgG were equally effective. When antiidiotypic antibody was administered 3 days after antigen no suppressive effects were observed. There was partial suppression when antiidiotypic antibody was injected on the same day as the antigen. Fab' and F(ab')₂ fragments of antiidiotypic IgG had no suppressive effect. Quantitative measurements revealed no significant differences among control and suppressed mice with respect to total concentration of precipitable anti-Ar antibodies produced.     

QUANTITATIVE INVESTIGATIONS OF IDIOTYPIC ANTIBODIES : IV. INHIBITION BY SPECIFIC HAPTENS OF THE REACTION OF ANTI-HAPTEN ANTIBODY WITH ITS ANTI-IDIOTYPIC ANTIBODY

Rabbit anti-idiotypic antibodies were prepared by injection of specifically purified anti-p-azobenzoate antibodies (D) from individual donor rabbits. Benzoate derivatives were found to be strong inhibitors of the reactions of D with anti-D antisera. There was a close correlation between the combining affinities of the benzoate derivatives used and their effectiveness as inhibitors. Compounds tested that are chemically unrelated to benzoate were ineffective. The results indicate either that the combining site of anti-benzoate antibody is part of an important idiotypic determinant, which is sterically blocked by hapten, or that the hapten induces a conformational change which alters idiotypic determinants not involving the active site. Such conformational changes, if they occur, must be restricted since hapten has little effect on the reactions of F(ab')₂ fragments of anti-benzoate antibodies with antisera directed to rabbit fragment Fab and no detectable effect on reactions with antibodies directed to allotypic determinants.     

SUPPRESSION OF IDIOTYPIC SPECIFICITIES IN ADULT MICE BY ADMINISTRATION OF ANTIIDIOTYPIC ANTIBODY

It has previously been shown that there are extensive idiotypic cross-reactions among antiphenylarsonate antibodies of A/J mice. The present work indicates that administration, into normal, adult A/J mice, of rabbit antiidiotypic antibody directed to A/J antiphenylarsonate antibody suppresses almost completely the subsequent production of antibody of the corresponding idiotype. No effect was noted on the formation of antibodies to the protein carrier or of antiphenylarsonate antibody of a different idiotype. The data are consistent with central suppression of production of the idiotypic antibody mediated through interaction with immunoglobulin receptors on lymphocytes.     

QUANTITATIVE INVESTIGATIONS OF IDIOTYPIC ANTIBODIES : II. NONPRECIPITATING ANTIBODIES

Idiotypic antibodies were investigated quantitatively by a method of indirect precipitation, which utilizes labeled F(ab')₂ fragments of specifically purified antibenzoate antibody from the donor, anti-antibody, and an antiglobulin reagent. The contribution of allotypic and hidden determinants to these reactions was excluded. Greater fractions of an idiotypic antibody population are precipitated by this method, as compared to direct precipitation, and in two instances large proportions of idiotypic antibodies were detected in populations which failed to form precipitates by double diffusion in agar gel. The greater sensitivity of the indirect method was attributed to its capacity to detect molecules bearing a small number of antigenic determinants. Extensive studies of cross-reactions, carried out by an inhibition technique, failed to reveal any strong reactions of anti-idiotypic antibodies with heterologous antibenzoate antibody preparations, heterologous sera, or IgG, although a few weak cross-reactions were noted. One definite cross-reaction was observed by a direct binding measurement with heterologous antiserum. Antisera prepared in more than one recipient against a single donor preparation reacted with identical or overlapping subpopulations of the donor molecules. Instances in which two recipient antisera reacted with different proportions of the molecules of a single donor provided evidence for the existence of more than one idiotypic antibody population in the antibenzoate antibody of an individual rabbit.     

EVIDENCE FOR THE LINKAGE OF THE IGCH LOCUS TO A GENE CONTROLLING THE IDIOTYPIC SPECIFICITY OF ANTI-p-AZOPHENYLARSONATE ANTIBODIES IN STRAIN A MICE

Anti-p-azophenylarsonate (anti-Ar) antibodies elicited in all strain A/J mice tested share one or more idiotypic specificities. These specificities are also found in the anti-Ar antibodies of mice of the closely related strain, AL/N, but not in those of BALB/c mice. Anti-Ar antibodies were elicited in congenic mice in which the IgC_H locus of AL/N mice, which controls allotypic markers in the constant regions of heavy chains, had been introgressively backcrossed for nine generations onto a BALB/c background; the mice were then rendered homozygous for the AL/N allotypic determinant. On the average, these antibodies were quantitatively equivalent, with respect to content of the cross-reactive idiotype, to those of AL/N mice. This indicates that the gene controlling the idiotype is closely linked to the IgC_H locus. Since idiotype must be a function of V region sequences, the results suggest close linkage of V_H and C_H genes. The cross-reactive idiotype was found in nearly all F₁ mice (C57/BL x A/J or BALB/c x A/J) tested.     

Suppression of hapten-specific delayed-type hypersensitivity responses in mice by idiotype-specific suppressor T cells after administration of anti-idiotypic antibodies

Delayed-type hypersensitivity (DTH) responses specific for the phosphorylcholine (PC) hapten were induced in BALB/c mice by immunization with syngeneic peritoneal exudate cells (PEC) coupled with diazotized phenyl-phosphoryl-choline. PC-specific DTH responses were elicited in such immunized mice after footpad challenge with PC-derivatized syngeneic spleen cells. Moreover, PC-immune lymph node cells could passively transfer PC-specific DTH responses to naive BALB/c mice and it was possible to demonstrate that the cells responsible for such passively transferred responses were T lymphocytes. Because the T-15 idiotypic determinant displayed on the TEPC-15 PC-binding myeloma protein is known to be a dominant idiotype associated with anti-PC antibody responses in BALB/c mice, an analysis was made of the effects of anti-T-15 idiotypic antibodies on the induction and expression of murine PC-specific DTH responses. Repeated injections of anti-T-15 idiotypic antiserum, raised in A/J mice by immunization with TEPC-15 myeloma protein, into recipient BALB/c mice both immediately before and after sensitization with PC-PEC virtually abolished the development of PC-specific DTH responses. Although administration of anti-T-15 antiserum effectively inhibited the induction phase of PC-specific DTH responses, these anti-idiotypic antibodies had no suppressive activity at the effector phase of these responses. The inhibition observed with anti-T-15 antibodies was highly specific for the PC hapten, and for PC-specific DTH responses of BALB/c but not A/J mice. Studies were conducted to address the possibility that anti-Id treatment induced suppressor T lymphocytes capable of specifically inhibiting the activity of PC-specific T cells participating in DTH responses. The results demonstrate that idiotype-specific suppressor T cells are, indeed, induced by treatment with anti-Id; moreover, such suppressor T cells, once induced, are highly effective in abrogating both the induction and the effector phases of PC-specific T cell-mediated DTH responses in BALB/c mice.     

Immunological analysis of rabbit anti-antibody systems

A study has been made of the production of antiidiotypic antibodies (anti-antibodies) arising during the immunization of 39 rabbits with 19 individual samples of rabbit anti-Proteus vulgaris x 19 antibodies adsorbed onto bacilli. In addition to the regular demonstration of antiidiotypic antibodies attention is drawn to the frequent occurrence of antiallotypic antibodies against molecules of immunoglobulin classes other than IgG, especially macroglobulins, which may arise during such immunization. In four cases attempts to raise autoantiidiotypic antibodies were unsuccessful, as expected. The idiotypic specificities (antigenic determinants) have been found mainly on IgG but also sometimes on IgM molecules. The individual specificity of the antiidiotypic antibodies appears to be absolute, as long as the antiallotypic antibodies are recognized and excluded; e.g., each idiotypic specificity is characteristic of only one single rabbit and of a single kind of antibody within that rabbit. These principles hold even when antibodies of rabbit families are examined: the parental idiotypic determinants could not be found in the offspring. In two samples tested the idiotypic specificities were found on the Fab fragment of IgG molecule but not on its antibody-combining site.     

DETECTION OF IDIOTYPIC CROSS-REACTIONS AMONG STREPTOCOCCAL ANTISERA FROM RELATED RABBITS

Idiotypic cross-reactions among antibodies to Group C streptococcal carbohydrate were studied using idiotypic antisera prepared in allotypically matched rabbits. Antibodies with idiotypic cross-specificity to one proband antibody were detected in 58% of the antisera from related rabbits, while approximately 1% of nonrelated rabbits produced antibody with this specificity. The cross-specificity was related to the group a (V_H) allotype of 133 rabbits tested with only one exception. Studies utilizing antisera against a second proband antibody failed to detect antibodies with idiotypic cross-reactivity among the same group of related rabbits. This result emphasizes the variation in expression of idiotypic determinants of antibodies. It was further shown that the presence of anti-IgG's in the streptococcal antisera interfere with the detection of idiotypic cross-reactions. These anti-IgG's masked the presence of antibodies with idiotypic cross-specificity when inhibition of precipitation tests were used for their detection.     

CLONAL NATURE OF THE IMMUNE RESPONSE TO PHOSPHORYLCHOLINE : IV. IDIOTYPIC UNIFORMITY OF BINDING SITE-ASSOCIATED ANTIGENIC DETERMINANTS AMONG MOUSE ANTIPHOSPHORYLCHOLINE ANTIBODIES

A new idiotypic determinant(s) on mouse anti-PC antibodies is described. Antibodies to the determinant(s) were raised in rabbits by immunization with HOPC 8, a PC-binding myeloma protein, and were isolated from HOPC 8 immunoadsorbent by elution with PC. These antibodies react with binding site determinants on anti-PC antibodies raised in all 15 inbred mouse strains tested regardless of histocompatibility or allotype, but fail to react with antibodies of other specificities or with anti-PC antibodies raised in other rodent species. These results correlate closely with other studies which show similar binding specificity of anti-PC antibodies raised in 17 different strains of mice. The site-associated idiotypic determinant(s) is clearly distinct from that detected by mouse anti-HOPC 8 antisera. This latter determinant(s) is present on anti-PC antibodies of only a few strains of mice and may not be in the binding site.     

Generation of antibody diversity in the immune response of BALB/c mice to influenza virus hemagglutinin. I. Significant variation in repertoire expression between individual mice

The paratypic and idiotypic diversity of the BALB/c antibody response to the hemagglutinin (HA) of the influenza A/PR/8/34 virus (PR8) was investigated using a panel of 125 anti-HA hybridoma antibodies derived from 14 BALB/c mice. The paratypic diversity, as assessed by a fine specificity analysis using 51 related influenza viruses, was extensive: 104 distinct paratopes were observed. In three instances, antibodies with indistinguishable paratopes were isolated from two individual mice. A minimum estimate of the size of the adult BALB/c anti-HA paratypic repertoire, calculated from these data, is 1,500. The generation of this diverse repertoire was studied by screening the anti-HA hybridoma panel for the presence of idiotypes (Id) that are markers for variable (V) region sequences derived from related germ line V genes. Three cross-reactive Id (IdX) that are markers for the V(k)21C, V(k)21B, and V(k)21A, D, E, or F L chain subgroups were found, respectively on 16, 1, and 10 anti-HA hybridoma antibodies derived from seven individual BALB/c mice. Thus, the V(k)21 IdX(+) hybridomas constitute 22 percent of the anti-HA hybridoma panel. The V(k)21 IdX are also present on 8.6 percent of K-bearing immunoglobulin in normal BALB/c serum. This suggests that the V(k)21 group is used preferentially in the BALB/c anti-HA immune response. The generation of the anti-HA repertoire was further studied using large panels of anti-HA hybridomas derived from two individual adult BALB/c mice. Anti-idiotypic antisera were raised in rabbits against individual hybridomas from each mouse. One anti-Id serum defined a family of four idiotypically and paratypically related, but not identical, antibodies from mouse 36, which represented 31 percent of the hybridoma antibodies isolated from this mouse. None of the 112 anti-HA hybridoma antibodies derived from 13 other individual mice showed idiotypic cross-reactivity. Furthermore, this Id could not be detected in anti-PR8 antisera from 75 individual BALB/c mice. Another anti-Id serum defined a family of 27 idiotypically related antibodies from mouse 37, which represented 50 percent of the hybridoma antibodies isolated from this mouse. Only 1 of the 71 hybridoma antibodies isolated from 13 other individuals was idiotypically cross-reactive. These results demonstrate that individual adult BALB/c mice express paratypically and idiotypically distinct antibody repertoires to the HA of influenza virus PR8. Based on these observations, we suggest that somatic mutation plays an important role in the generation of the adult anti-HA repertoire. Mechanisms that could account for differences in repertoire expression among individual mice are discussed.     

The monoclonal anti-phosphorylcholine antibody response in several murine strains: genetic implications of a diverse repertoire

The idiotypic identification of monoclonal antibodies has been used to define and enumerate clonotypes within the murine repertoire of B cells specific for phosphorylcholine (PC). The response in the BALB/c strain is dominated by a single antibody specificity which is identical to TEPC 15 protein; however, antibody without the TEPC 15 idiotype appears heterogeneous by idiotypic cross-reactivity and hapten inhibition of binding to antigen. Dissection of the PC-specific repertoire in the AKR, A/He, and C3H strains has indicated that some monoclonal antibodies share binding-site idiotypic determinants with TEPC 15, although these clones represent a minority of the precursor cells. In addition to providing insights into the heterogeneity and expression of the murine B-cell repertoire, these studies emphasize structural relationships between PC-specific clonotypes. Within the BALB/c strain, some antibodies share combining-site-related idiotypic specificities with TEPC 15, but differ in other variable region determinants. Among allotypically distinct strains, there exists a remarkable similarity of variable region determinants in at least a minority of antibodies.     

IDIOTYPY OF RABBIT ANTIBODIES : I. COMPARISON OF IDIOTYPY OF ANTIBODIES AGAINST SALMONELLA TYPHI WITH THAT OF ANTIBODIES AGAINST OTHER BACTERIA IN THE SAME RABBITS, OR OF ANTIBODIES AGAINST SALMONELLA TYPHI IN VARIOUS RABBITS

Sera of rabbits immunized against Salmonella typhi have been studied for the idiotypy of certain of their components, i.e., the property of these components to possess an antigenic specificity which is different in individual rabbits, and which varies with the antigens against which these rabbits have been immunized. The reagent used (precipitating anti-idiotypic sera) have been prepared by injecting rabbits with bacteria agglutinated by anti-S. typhi sera (immunizing sera) as was done in the first observations by the authors of the phenomenon in the rabbit. These first observations have been confirmed and extended. In contrast to allotypy, the anti-idiotypic sera precipitate the corresponding immunizing sera, but not the sera taken in the immunizing rabbits prior to their immunization against S. typhi, nor the immunizing sera absorbed with the somatic antigen of S. typhi, demonstrating that idiotypes are antibodies. The idiotypic specificities of the antibodies of one rabbit against S. typhi are not detected in the antibodies of the same rabbit against another noncross-reacting Salmonella (S. tranoroa) and vice versa; nor are they detected in the anti-pneumococcal antibodies of the same rabbit. Each anti-idiotypic serum fails to precipitate anti-S. typhi sera of rabbits other than the immunizing one except for certain extremely faint reactions, the significance of which has not been established. The idiotypic specificities of anti-S. typhi antibodies of three rabbits were not found in anti-S. typhi antibodies of their parents. This lack of a sign of hereditary transmission of idiotypic specificities contrasts with allotypy. The apparent role of random chance in the determinism of the idiotypic patterns or of the idiotypic determinants has been discussed. Unless it were admitted that antibodies with similar functions do not exist in different individuals, idiotypy apparently adds an order of magnitude to the antibody variability which had been previously envisaged. In one given individual, the heterogeneity of the idiotypic specificities seems to be less extended than that of the antibody functions. The possible relationships between these two levels of molecular variability and between the corresponding levels of cellular variability have been discussed.     

IDIOTYPIC SPECIFICITY OF RABBIT ANTIBODIES TO STREPTOCOCCAL GROUP POLYSACCHARIDES

Anti-idiotypic antisera against six restricted rabbit streptococcal group specific antibodies have been raised in rabbits matched for allotypes. All these antisera reacted specifically with their homologous idiotypes on double-diffusion tests in agarose gel. In addition, they showed a high incidence of cross-specificities with group-specific hyperimmune sera induced in both closely related and unrelated individuals. These precipitating cross-specificities could be explained for two systems by the interference of rheumatoid factor. Two idiotypic antibody systems have been analyzed in detail; these were restricted antibodies produced in a father and in one of his offspring. The methods employed included binding inhibition of radio-labeled homologous Fab fragments and hemagglutination inhibition with homologous idiotypic coat. The data demonstrated that only related rabbits produced, besides non-cross-reacting antibodies, idiotypically similar antibodies raised to the same antigen. About one-third of the cross-reactive idiotypes showed binding inhibition between 31 and 92%. Inhibition of binding above 50% in the paternal idiotypic system was only achieved by one offspring antibody whereas the F₁ progeny idiotypic system was inhibited to this extent by seven antibodies of related rabbits. In contrast, 87.5% and 91.7% of antibodies of unrelated rabbits were less than 20% inhibitory. Within this study two idiotypically identical antibodies have not been found. This implies that A-variant-specific antibodies of related rabbits which produced antipolysaccharide antibodies were structurally different. Cross-reaction, even if greater than 90% by binding inhibition, appears to involve only part and not all of the variable regions.     

The expression of anti-poly(LGlu60, LPhe40) idiotypic determinants dictated by the gene products in the major histocompatibility complex

Antibodies raised in SWR/J mice (H-2q, Igc) to the random copolymer poly(LGlu60, LPhe40) (GPhe) were purified by immunoadsorbent chromatography and used to immunize a New Zealand red rabbit. The rabbit anti-idiotypic antiserum thus produced strongly inhibited the binding of 125I-GPhe by anti-GPhe antisera produced only in mice of H- 2q haplotype, and had no effect on the binding of GPhe by anti-GPhe antisera produced in mice of other haplotypes, namely, H-2k and H-2p. The anti-idiotypic antiserum also inhibited the binding of GPhe by anti- GPhe-methylated bovine serum albumin antisera produced only in mice of H-2q haplotype. No linkage to Ig allotype was observed. The anti-GPhe antisera produced in F1 mice the anti-idiotypic antiserum demonstrating the dominant presence in these F1 mice of idiotypic determinants whose expression is dictated by the H-2q major histocompatibility complex (MHC). The anti-idiotypic antiserum also inhibited the binding of 125I- poly)LGlu56, LLys35, LPhe9) and 125I-GPhe antisera produced only in mice of H-2q haplotype. These specificities were also confirmed by the inhibition of the plaque-forming cells. It was concluded that the antibodies produced in mice of H-2q haplotype against GPhe and GLPhe share common idiotypic determinants that are recognized by the anti- idiotypic antiserum. A possible explanation for the unique findings that the expression of anti-GPhe idiotypic determinants in mice of H-2q haplotype are dictated by the gene product in the MHC is that the macrophages in mice of H-2q haplotype present unique determinants of GPhe polymer in the response process to GHphe.     

STUDIES OF IDIOTYPIC ANTIBODIES : PRODUCTION AND CHARACTERIZATION OF AUTOANTIIDIOTYPIC ANTISERA

Rabbits were immunized with a hapten-protein conjugate and sera were collected for 189 days. The antihapten antibodies were purified by affinity chromatography, then the same animal that synthesized the antibody was reinjected with polymerized F(ab')₂ fragments of antihapten antibodies. Sera were collected after autoimmunization and tested by an indirect radioimmunoassay technique for reaction with [¹²⁵I]F(ab')₂ fragments of the original antihapten antibody. Results showed that each individual responded to its own F(ab')₂ and the antisera were specific for antihapten antibodies of that individual. Quantitative allotype assays established the immunoglobulin nature of the labeled test antigen. Inhibition assays showed that the reaction was specifically inhibitable with hapten. The relationship of this system with other idiotypic systems and the possible autoimmune implications of autoantiidiotypic antibodies are discussed.     

Syngeneic monoclonal antiidiotype can induce cellular immunity to reovirus

A syngeneic monoclonal antiidiotypic antibody was generated in BALB/c mice after repeated immunization with a BALB/c monoclonal anti-reovirus hemagglutinin (HA) antibody. The resultant syngeneic monoclonal antiidiotypic antibody, in the absence of adjuvant, was found to be capable of priming both BALB/c (H-2d, Igh-1a) and C3H/Hej (H-2k, Igh-1j) mice for Lyt-1+- and Lyt-2+-dependent responses against the mammalian reovirus. By the use of intertypic reassortants and variant virus analysis, the specificity of the response was finely mapped to the neutralization domain of the viral hemagglutinin (HA). Using purified monoclonal antiidiotype, we were able to compare the potency of antiidiotype to virus in terms of induction of immunity. 8 X 10(8) protein molecules were able to prime for cellular responses to reovirus. These studies indicate that in the reovirus system, T cells and B cells share idiotypic configurations, and that antiidiotypic antibodies of the type described herein may be useful in the development of vaccines against certain viral infections.     

ASSOCIATION OF H-2 TYPES WITH GENETIC CONTROL OF IMMUNE RESPONSIVENESS TO IGG (γ2a) ALLOTYPES IN THE MOUSE

Immune responsiveness to IgG allotypes in the mouse was found to be controlled by an immune response gene Ir-IgG linked to the H-2 locus. This was demonstrated by the analysis of the immune response to BALB/c IgG (γ2a) myeloma proteins in mice of various H-2 types from five different linkage groups of immunoglobulin heavy chains. Antisera were examined for antibodies to idiotypic (Fab) and allotypic (Fc) specificities. No immune response to BALB/c IgG myeloma proteins was found in mice with the same heavy-chain immunoglobulin linkage group as BALB/c but of different H-2 types. In mice with immunoglobulin heavy chains that are different than BALB/c, a high immune response to IgG myeloma proteins was found in H-2 types b, bc, p, r, s, and v; a low response in a, d, k, and q. The Ir-IgG gene is controlled by a dominant autosomal gene.     

IDIOTYPE EXPRESSION AND THE INHERITANCE OF MOUSE ANTIBODY CLONES

The inheritance of idiotypes was investigated using idiotypic antisera against two monoclonal antibodies to streptococcal carbohydrates derived from A/J mice. Each of the two idiotypes was characterized by a special frequency of expression. One of the idiotypes was expressed in more than 80% of A/J mice, the other in less than 20%. The idiotypes of both antibodies were strain specific and were transmitted to (A/J x BALB/cJ)F₁ hybrid mice. Furthermore, both idiotypes remained associated with the A/J heavy chain C region allotype in (A/J x BALB/cJ)F₁ hybrid mice. The results suggest that idiotypes are specified by allelic V genes, and that the heavy chain idiotype locus is linked to the heavy chain allotype locus.     

Mutation in a new H-2-associated histocompatibility gene closely linked to H-2D.

Sequential precipitations of soluble BALB/c antigen with antisera detecting private and public H-2 specificities indicated three distinct classes of molecules of 45,000 mol wt. However, only two of these classes of molecules were detectable in antigen from the loss mutant, BALB/c-H-2db. The class of molecules, detectable in the wild-type strain but missing in the mutant, does not bear private specificities but does react with an antiserum detecting H-2 public specificities. Absorption in mutant mice of the antiserum to public specificities, left antibodies specific for the antigen detectable in BALB/c but not BALB/c-H-2db. Genetic mapping studies using this specific antiserum indicated that the antigenic loss of this mutant is in a gene which maps in or close to the H-2D region, separable from the H-2K, S, G, Qa-2, and Tla regions.