Idiotype profile of an immune response. I. Contrasts in idiotypic dominance between primary and secondary responses and between IgM and IgG plaque-forming cells

Antigen-induced changes in odor attractiveness and reproductive output in male mice

Modulation of social signals by antigen-induced immunoenhancement is a significant component of behavioral and reproductive adaptations of a host population to parasitic pressure. To investigate this concept, we studied odor attractiveness and reproductive output of ICR male mice treated with keyhole limpet hemocyanin (KLH) as an antigenic stimulus. We collected urine samples for olfactory preference tests (control vs. KLH administration) on different days following treatment. We found that the differences in odor attractiveness between control and immunized males, which were observed on the 3rd day, disappeared soon afterwards. Odor attractiveness of male mice positively correlated with their immunoresponsiveness, which was assessed by the sum of anti-KLH IgG1 and anti-KLH IgG2a titers. According to the hypothesis of terminal investment, antigen-treated males had higher reproductive output in comparison with control males and produced more progeny as a result.

The molecular evolution of the immune response: idiotope-specific suppression indicates that B cells express germ-line-encoded V genes prior to antigenic stimulation

Antibodies expressed by the immune B cell population are characterized by variable region amino acid substitutions resulting from somatic nucleotide replacement (somatic mutation). This is not true of antibodies expressed by the "naive" B cell population. It is at present unclear whether this discrepancy is due to the preferential clonal selection of a pre-existing subpopulation of naive B cells that express variable regions altered via nucleotide replacement, or whether the process of nucleotide replacement occurs only during the antigen-dependent stages of B cell differentiation. To address this question we have used anti-idiotypic suppression to functionally delete B cells that express particular variable-region structures from the antigen-responsive repertoire. Suppression of the major cross-reactive idiotype (IdCR) expressed in strain A mice in response to p-azophenylarsonate (Ars) was induced using the monoclonal anti-IdCR antibody AD8. The idiotope recognized by AD8 is easily destroyed by alteration of IdCR variable-region structure via nucleotide replacement. The IdCR anti-Ars immune repertoire is characterized by antibodies that lack the AD8-cognate idiotope due to nucleotide replacement. However, complete suppression of the IdCR could reproducibly be achieved by administration of AD8 prior to Ars immunization. This result indicates that all IdCR-expressing B cells also express the AD8-cognate idiotope prior to immunization. Thus, somatic nucleotide replacement must occur exclusively during the antigen-dependent stages of B cell differentiation in this system.

Affinity maturation in the arsonate system: lack of dominance of high-affinity antibody subpopulations

Affinity maturation was studied by the analysis of the kinetics of the appearance of antibody subpopulations with different affinities during the immune response, using an hapten-inhibition ELISA. The immune response in KLH-Ar-immunized A/J mice was used as a model system. Five antibody subpopulations of different affinity (10(3)-10(7) M-1) could be detected, the relative concentrations of which changed during affinity maturation. The high-affinity antibody subpopulations did not represent the major fraction at any stage during affinity maturation. The appearance of the highest affinity subpopulation (10(7) M-1), despite exhibiting relative concentrations no higher than 12%, produced an important increase in average affinity. On the other hand, its disappearance at the end of the maturation process could explain the average affinity decrease observed at this stage. Our results indicate that affinity maturation cannot be explained by the dominance of high-affinity clones, as proposed by Siskind & Benacerraf (1969). The increase in affinity could rather be due to the progressive appearance of low percentages of high-affinity clones, which are not present in the primary response and never become dominant.

Immunoresponses to Neisseria meningitidis epitopes: suppression of secondary response to phosphorylcholine is carrier specific

Results of our previous work have shown that Neisseria meningitidis serogroup B M986 can induce a phosphorylcholine (PC)-specific plaque-forming cell immunoresponse in mice. Also, a single injection of a relatively low dose of meningococci in NBF1 female mice induced a priming time-dependent suppression on subsequent meningococcus challenge. This suppression was not due to switching to another class of immunoglobulin nor to the presence of a capsule on N. meningitidis. In this study we show that suppression induced by meningococcus is carrier specific. Furthermore, we offer evidence suggesting that the structure(s) on meningococcus that trigger this suppression is heat labile and different from the antigenic structure(s) recognized by the suppressed B cells. In addition, we found that there is a gradual increase in antibody secretion rates of N. meningitidis-induced anti-PC plaque-forming cells that correlates with N. meningitidis priming time. Rather unexpected was the fact that pretreatment of mice with PC-keyhole limpet hemocyanin (thymus-dependent antigen) had a great influence on the subsequent PC-specific immunoresponses induced by N. meningitidis and PC-coupled heat-inactivated meningococcus [PC-(NMB)HI], as shown by (i) a striking decrease in T15 idiotype expression, (ii) concomitant direct anti-PC plaque-forming cells reduction, (iii) switching to immunoglobulin G (N. meningitidis-induced immunoresponse) or immunoglobulin G plus immunoglobulin A [PC-(NMB)HI-induced immunoresponse], and (iv) a significant increase in heterogeneity of plaque-forming cell secretion rates. The possibility that N. meningitidis, PC-(NMB)HI, and PC-KLH stimulate B lymphocytes pertaining to three different subpopulations embedded in distinct regulatory circuits is discussed, with emphasis on the interrelationships between T-dependent and T-independent lymphocyte compartments. We focus on the possibility of the existence of high-level regulatory circuits in which lymphocyte subpopulations or sets of lymphocyte subpopulations with different requirements of activation are connected.

Idiotypic properties of the murine anti-arsonate antibody response: B- and T-cell influences

In a previous report characterizing the arsonate (ABA)-specific plaque-forming cell (PFC) responses of A/J mice induced by ABA-KLH, two interesting characteristics of the idiotypic (Id) profile were noted: (1) an apparent Id selectivity in the isotype switch since the earliest appearing IgG PFC in the primary response were significantly more "cross-reactive Id" (CRI)-dominant than the IgM PFC population, and, (2) a temporal waning of CRI dominance with time among IgG PFC, from 75-100% CRI+ PFC to about 25-45% CRI+ PFC in secondary responses. Experiments were performed to determine whether these effects are largely attributable to T or to B cells. Mice were immunized with a T-independent (TI) form of ABA (ABA-Brucella abortus) and apparent Id selectivity was observed; the earliest IgG PFC averaged 75% CRI+ while IgM PFC were only 39% CRI+. Due to the TI nature of the Ag, this provides suggestive, but not conclusive, evidence that the Id asymmetry in the isotype switch may be attributable to the direct interaction of Ag with B cells. Other studies addressed the temporal shift in CRI dominance. First, it was found that preexposure of mice to either KLH or to ABA (on an irrelevant carrier) resulted in diminished CRI dominance in subsequent "primary" responses to ABA-KLH. Secondly, adoptive transfer experiments with B and T cells from virgin mice (Bv, Tv) or ABA-KLH-primed mice (Bp, Tp) showed that recipients of Bv + Tp or Bp + Tv generated anti-ABA PFC responses with intermediate CRI levels. The Tv cells had some preferential tendency to activate CRI+ clones in the Bp population. The results demonstrate that CRI levels are jointly determined by the immune status of both B and T cells. A simple model is offered which accounts for early Id dominance and its gradual decline and has as its central postulate the assumption that CRI+ B cells in the virgin ABA-specific repertoire have an affinity advantage over CRI- clones.

The control of antibody diversity during IgM and IgG anti-sheep red cell responses in mice

The isoelectric heterogeneity of both IgM and IgG murine anti-sheep red cell serum antibodies has been examined using an adaptation of published methods. It was found that the IgM spectra were restricted in a characteristic manner, implying oligoclonality. In cell transfer experiments, the T cell dependency of the IgM responses was confirmed. Further, helper cells appeared to switch on IgG antibody production and, simultaneously, recruit many novel IgG-forming clones into the response. The pattern of the IgM oligoclonality was attributed in part to the inheritance of genes at, or closely linked to, the Igl heavy chain locus. These findings are discussed in relation to current research on the regulation of diversity.

Independent regulation of serologically distinct idiotypes in F1 hybrid mice

We have investigated the regulation of expression of two distinct intrastrain cross-reactive idiotypes, CRIA and CRIC , characteristic of anti-p-azophenylarsonate (anti-Ar) antibodies of the A/J and BALB/c strains, respectively, in (BALB/c X A/J)F1 ( CAF1 ) mice. Such hybrid mice were found to synthesize antibodies with each idiotype when immunized against the Ar hapten group, although the expression of each was significantly reduced as compared with the parental strain. CAF1 mice were pretreated with idiotypic-specific antibody reagents and subsequently hyperimmunized against the Ar hapten. Analysis of the idiotypes present in immune sera showed that suppression of either CRI did not concomitantly suppress the expression of the other. Alteration of the expression of one idiotype was not, however, without influence on the other; the expression of CRIC was markedly enhanced in mice suppressed for CRIA.

Immunodominant protein epitopes. II. The primary antibody response to hen egg white lysozyme requires and focuses upon a unique N-terminal epitope

The antibody response to a defined protein antigen, hen egg white lysozyme (HEL) has been investigated using an aminopeptidase-treated HEL molecule, des-1,2,3-HEL (AP-HEL). Surprisingly, removal of these three N-terminal residues eliminates an epitope which is a dominant B cell determinant recognized in the primary antibody response to HEL. Thus, the initial antibody response focuses on a very small region of the molecule. Even more striking is the observation that removal of this epitope markedly reduces the immunogenicity of HEL. Therefore, the epitope is not only the focus of the primary antibody response, but is essential for the initiation of the response. This report demonstrates that a selective mechanism must be activated during the response to this protein antigen. Of the multitude of B cell determinants present on HEL, only a limited number are focused upon by the immune system.

Human auto-antiidiotypes regulating T cell-mediated reactivity to tetanus toxoid

While investigating the effect on B cells of repetitive in vivo immunization with tetanus toxoid (TT), we observed the subsequent development of specific anergy for T cell delayed hypersensitivity (DTH) to TT. This appeared approximately 35 d after a series of five booster immunizations. Concurrently, in vitro T cell blastogenic responses were preserved. Serum obtained when the skin tests were nonreactive demonstrated a profound inhibitory activity on T cell reactivity. This activity was shown to be anti-antibody activity that was both anti-F(ab)'2 and, specifically, anti-TT F(ab)'2. It blocked binding of TT to a pool of allogeneic antibodies and also inhibited allogeneic antigen-specific T cell blastogenesis. Thus, we could identify activity in the serum of hyperimmunized individuals that appeared auto-anti-idiotypic (anti-id) and represented a single or family of major crossreacting idiotypes (id) for TT. The expression of the auto-anti-id correlated with the loss of T cell reactivity in vivo and in vitro. Subsequent examinations revealed persistent, specific cutaneous anergy beyond six months, which was then associated with a failure of T cells to react with antigen in vitro. Mixing experiments with cells from these later times and cryopreserved autologous cells obtained prior to hyperimmunization revealed there had been the development of antigen-specific T suppressor cells. Thus, in vivo DTH tolerance following hyperimmunization was associated with an inhibitory serum activity that appeared to be anti-id. Persistence of tolerance (greater than 6 mo) occurred with the development of T suppressor cells.

Non-dinitrophenyl-binding immunoglobulin that bears a dominant idiotype (Id460) associated with antidinitrophenyl antibody is specific for an antigen on Pasteurella pneumotropica

We have previously described an idiotype (Id460) that transiently dominates anti-2,4-dinitrophenyl (DNP) antibody responses of mice that possess the appropriate Igh-V and V kappa genotypes. Normal serum has significant levels of Id460 that does not bind DNP, and hybridomas derived from spleen cell fusions that produce monoclonal antibodies with these characteristics have been generated. Many of these monoclonal, Id460-positive antibodies bind the opportunistic mouse pathogen Pasteurella pneumotropica. P. pneumotropica induces a marked increase in serum Id460 titers without significantly increasing serum anti-DNP titers. Both normal serum and P. pneumotropica-induced Ig460-positive immunoglobulin specifically bind to P. pneumotropica. These results suggest that the normal serum Id460-positive immunoglobulin is induced by environmentally encountered antigens on P. pneumotropica. We propose that this naturally occurring Id460 activates antiidiotypic regulatory cells that in turn promote production of Id460-positive anti-DNP antibody following DNP-ovalbumin immunization. These data are compatible with those obtained in several other idiotypic systems that suggest that dominant idiotypes may be associated with antibodies that have been evolutionarily selected for expression because of their specificity for antigens on environmentally encountered pathogens.

Expression of defined idiotypes throughout the BALB/c anti-fluorescyl antibody response: affinity and idiotype analyses of heterogeneous antibodies

Heterogeneous BALB/c anti-fluorescyl antibodies were shown to display increases (greater than 50-fold) in binding affinity from the primary through the tertiary responses. The structural basis of such affinity maturation and the diversity exhibited by anti-fluorescyl antibodies was examined by idiotypic analysis using a panel of anti-idiotype reagents specific for seven different monoclonal antifluorescyl antibodies. Because these clones exhibited binding affinities characteristic of a secondary or hyperimmune response, it was possible to examine the mechanism of affinity maturation by determining the prevalence of the seven idiotypes (Id-4-4-20, Id-20-19-1, Id-20-20-3, Id-6-10-6, Id-20-4-4, Id-4-6-10 and Id-6-19-1) in specifically purified heterogeneous preparations with low (i.e. primary response) or high (i.e. secondary and tertiary responses) binding affinities. Four of the idiotypes were not detected in heterogeneous preparations and thus each represented less than 0.1% of the total anti-fluorescein repertoire. Although results indicated that each of three other clones expressed unique or private idiotypic determinants not present in the heterogeneous population, these idiotypes (Id-4-4-20, Id-6-10-6, Id-6-19-1) were detected and ranged from approximately 0.2 to 2.0% of the repertoire. However, results indicated that each clone expressed unique or private idiotypic determinants not present in the heterogeneous population. Determinants expressed by such high-affinity monoclonal antibodies were expressed equally in all heterogeneous preparations examined. Because those determinants which were expressed were found in either low- or high-affinity heterogeneous antibodies, it is likely that the higher affinities exhibited by monoclonal antibodies derived from a secondary response are associated with unique idiotypic determinants which were not detected in polyclonal preparations. Hence, the process of affinity maturation may find as its structural correlate a mechanism such as somatic mutation which generates individual or unique idiotypes.

The occurrence of defined idiotypes on autoantibodies to mouse thyroglobulin

Anti-idiotypic antibodies were raised in rabbits to three monoclonal mouse autoanti-thyroglobulins. Of the idiotypes recognized, one was unique to that monoclonal, while the other two showed evidence of sharing idiotopes with other monoclonal anti-thyroglobulin (TG) idiotypes, the IgM idiotype in particular being found on nearly half of the hybridomas studied. Two of the idiotypes could be detected in the sera of mice with experimental allergic thyroiditis (EAT), but they constituted only a very small percentage of the total anti-TG present. In spite of its low levels in EAT mice the D8 idiotype could be induced by injection of anti-idiotype and TG and in this case it constituted up to 20% of the anti-TG activity in individual mice, showing a strain-related association between the idiotype and autoanti-TG.

Idiotype profile of an immune response. II. Reversal of the relative dominance of major and minor cross-reactive idiotypes in arsonate-specific T-independent responses

Two different cross-reactive idiotype (CRI) groups are distinguishable in the Ab response of A/J mice to the p-azobenzenearsonate (ABA) hapten: CRIA and CRIm. These two groups showed distinct patterns of relative dominance in the ensuing response depending on whether the inducing Ag was a T cell-dependent (TD) form of ABA, such as ABA-KLH or ABA-CGG, or a T-independent type 1 (TI-1) form, such as ABA-Brucella abortus or ABA-lipopolysaccharide (LPS), and on whether the response was elicited in vivo or in vitro. The CRI+ component of primary in vivo plaque-forming cell (PFC) responses to TD ABA Ags was largely (greater than 90%) CRIA+ as was, to a slightly lesser extent (greater than 75%) the CRI+ portion of secondary or hyperimmune serum Ab or PFC responses to the same Ags. In contrast, in vivo primary and hyperimmune PFC responses to ABA-Bru or ABA-LPS showed a significantly lower CRIA/CRI ratio, averaging 0.5-0.6, with some individual mice giving figures as low as 0.2, indicating predominance of CRIm over CRIA. Serological analysis of hyperimmune anti-ABA Abs from a group of 5 A/J mice immunized with ABA-Bru gave a figure of less than 0.5 for the CRIA/CRI ratio. The most striking disparity from the TD pattern was seen in primary in vitro PFC responses to the TI ABA Ags; here ratios of less than 0.2 were generally seen. Since T cell removal did not alter the Id pattern in the TI responses, CRIA-specific Ts cells do not account for the weak expression of CRIA in such responses. We propose a model that explains these results on the basis of differential expression of IdX dominance by two distinct B cell subpopulations--equatable to the Lyb-5+ and Lyb-5- B cell subsets--along with differential relative activation of these subsets in different types of responses. Examination of anti-ABA PFC responses of F1 progeny of CBA/N and A/J mice to ABA-Bru lends support to this hypothesis since CRIA expression was significantly lower in mice with the xid defect.

Use of anti-idiotype immunosorbents to isolate circulating antigen-specific T cell-derived molecules from hyperimmune sera

We immunized four different sheep with antigen-binding material found in the serum of BALB/c mice 4 days after primary immunization with sheep erythrocytes (SRBC). The resultant antibodies made by the sheep contained a specificity(ies) that appeared to react with a dominant idiotype present on SRBC-specific Lyt-2+ T cells. The antiserum made by the sheep markedly inhibited the formation of antigen-specific rosettes by SRBC educated T cells but did not inhibit T cells educated to other heterologous erythrocytes from forming crossreacting rosettes with SRBC or specific rosettes with the homologous erythrocytes. The "anti-Id serum" was depleted of all activity against known immunoglobulin isotypes and light chains and then was used to isolate antigen-binding molecules from mice that were hyperimmunized with SRBC. The ShId+ material so isolated could be divided into two main groups--one that expressed immunoglobulin determinants, and one that did not. The former represented 15-25% of the ShId+ protein isolated and comprised a minority of the anti-SRBC antibody in the anti-SRBC serum; the latter group of proteins bound sheep glycophorin specifically and expressed constant region determinants found on a number of other antigen-specific T cell factors. These experiments suggest that antigen-binding molecules made by T cells display much less heterogeneity than do antibodies and also show that the serum of hyperimmune mice contains significant amounts of T cell-derived antigen-specific immunoregulatory molecules.

Regulation of azophenylarsonate-specific repertoire expression. 1. Frequency of cross-reactive idiotype-positive B cells in A/J and BALB/c mice

A large proportion of p-azophenylarsonate (ARS)-specific antibodies from A/J mice share a cross-reactive idiotype (CRIA) that comprises a family of closely related but nonidentical clonotypes. I determined that only 2.6 % (7 out of 267) A/J ARS-specific monoclonal antibodies generated in the splenic focus system possess the predominant CRIA. Because ARS-specific B cells are present at a frequency of 1/68,000 B cells, the frequency of the entire idiotype family is 1 per 2.8 X 10(6) splenic B cells. Thus, there is a striking discrepancy between the representation of this idiotype at the clonal precursor cell level and the serum antibody response. In addition, BALB/c mice have the potential to generate CRIA-positive precursor cells within their nonimmune repertoire. When A/J mice are immunized with ARS-protein conjugates, the serum antibody response and precursor cell population are both dominated by CRIA. The frequency of CRIA-positive B cells increases over 100-fold after immunization, whereas CRIA-negative precursor cells may initially decrease, followed by a later rise in frequency. Finally, although ARS-specific precursor cells are present in high frequency at birth, CRIA-positive monoclonal anti-ARS antibodies are not observed during the early neonatal period. These data provide evidence to suggest that complex regulatory networks influence precursor cell and serum antibody expression.

Study of the idiotypy of lipopolysaccharide-specific polyclonal and monoclonal antibodies

The monoclonal antibodies produced by a variety of hybridomas making antibody specific for E. coli 0113 lipopolysaccharide (LPS) were purified by affinity chromatography and their fine specificity studied. All reacted specifically with the polysaccharide moiety of LPS from E. coli 0113 and from Neisseria lactamica; two reacted with LPS from Pseudomonas aeruginosa and one reacted with LPS from Klebsiella pneumoniae. Polyclonal and monoclonal syngeneic and semi-syngeneic anti-idiotypic antisera were produced to study the idiotypy of LPS-specific monoclonal antibodies which express a complex cross-reactive idiotype (IdX) as well as individual idiotypes. E. coli 0113 LPS-specific antibodies produced by BALB/c mice express this IdX and the kinetics for its expression was examined using mice either primed or hyperimmunized with LPS; idiotypic maturation was observed, but we were unable to detect an auto-anti-idiotypic antibody response. This IdX was expressed on E. coli 0113 LPS-specific antibodies from all strains of mice examined, indicating that its expression is not restricted by genes linked to the IgCH locus.

Deregulation of idiotype expression. Induction of tolerance in an anti-idiotypic response

The induction of tolerance in an anti-idiotypic response was attempted by in vivo exposure to excess idiotype. Monoclonal immunoglobulin from the anti-p-azobenzenearsonate (ABA) hybridoma R16.7 was used as a representative of cross-reactive idiotype-positive (CRI+) antibodies because this hybridoma protein (HP) shares one or more closely related public idiotypic determinants with the serum CRI in A/J mice. Immunologic unresponsiveness was established by a single injection of the R16.7 idiotype and persisted for at least 6 wk. The level of circulating anti-idiotypic antibodies in tolerized A/J mice was significantly depressed after immunogenic challenge with eigher antigen, ABA-keyhole limpet hemocyanin (KLH), or the idiotype R16.7 HP. Experimental depletion of anti-idiotypic antibodies by tolerization allowed assessment of immunoregulation within this altered idiotype-anti-idiotype network. Deregulation of idiotype expression in tolerized mice challenged with ABA-KLH was manifest with up to 96% of the anti-ABA antibodies cross-reacting with the R16.7 idiotype. This selective enhancement of a major idiotype was accomplished without substantial alteration of the level of the overall anti-hapten response. Both the unresponsiveness established in anti-idiotypic antibody-producing cells and the enhanced synthesis in idiotype-producing cells were stable upon adoptive transfer into lethally irradiated, syngeneic recipients. Finally, previous immunization with the antigen ABA-KLH interfered with the induction of unresponsiveness to the idiotype. This interference is presumed to be mediated by prior activation of anti-idiotypic cells and/or antibody because injection of antigen with tolerogenic idiotype did not abrogate tolerance induction.

The relation of idiotype expression to isotype and allotype in the anti-p-azobenzenearsonate response

The distribution of idiotype-positive plaques in mice of various strains injected with T-independent (TI) and T-dependent conjugates of p-azobenzenearsonate (Ars) has been investigated. With maturation of the responses there is a progressive loss of dominance of the major cross-reactive idiotype (CRI) in A/J and C.AL-20 mice. The extremes are represented by the predominantly CRI+ IgM plaque response to a single injection of the TI antigen, Ars-coupled Brucella organisms (Ars-Br), and the low frequency of CRI+ plaques in the polyisotypic response elicited by Ars-KLH (keyhole limpet hemocyanin) in adjuvant. The secondary response to Ars-Br was characterized by an intermediate display of idiotype-positive plaques in IgM, the IgG subclasses and IgA. Detailed analyses of the distribution of CRI+ plaques between isotypes in 60 mice hyperimmunized with Ars-KLH revealed that the expression of idiotype in any of the IgG subclasses and IgA was constant and independent. This is interpreted to indicate random assembly of VH with C gamma and C alpha genes during the switch. BALB/c and C3H mice also express a predominant idiotype during primary and secondary responses to Ars-Br as detected by our heterologous anti-A/J CRI serum. These strains only very rarely maintain the idiotype after hyperimmunization with Ars-KLH. We conclude that hyperimmune responses which probably involve multiple modes of regulation give a poor indication of the germ-line V gene repertoire.

Expression of an idiotype (Id-460) during in vivo anti-dinitrophenyl antibody responses. III. Detection of Id-460 in normal serum that does not bind dinitrophenyl

Using an anti-idiotypic antibody previously characterized as specific for the hapten binding site of the 2,4-dinitrophenyl (DNP)-binding BALB/c myeloma protein MOPC-460, we have detected substantial amounts of this idiotype (Id-460) in the serum of normal mice. Whereas the idiotypic material in DNP-immune serum binds to DNP, the Id-460-positive material in normal mouse serum is not specific for DNP. The material in normal serum appears to be immunoglobulin. Furthermore, Id-460-positive, non-DNP-binding monoclonal immunoglobulins that completely inhibit our assay for Id-460 are repeatedly isolated when hybridomas are prepared from LPS-activated normal spleen cells. These data are interpreted in the context of Jerne's network hypothesis. It is our conclusion that the non-DNP-binding form of Id-460 is the inherited form and that this form establishes an idiotypic network favoring the production of anti-DNP bearing Id-460. Thus, the paradox of finding an inherited idiotype in the antibody response to the nonpathogen DNP may be resolved by proposing that the true form of Id-460 is specific for an environmental pathogen and that Id-460 dominance in the anti-DNP response is simply a consequence of idiotype-specific regulatory events preconditioned by Id-460-bearing immunoglobulin specific for antigenic determinants unrelated to DNP.

Idiotypic repertoire of anti-hen eggwhite lysozyme antibodies probed with hybridomas. Selection after immunization of an IdX marker common to antibodies of distinct epitope specificity

A panel of hybridoma antibodies obtained from lymphoid cells that were fused during a primary response ("early") or a secondary response ("late") gave results concordant with analysis of conventional, in vivo-produced anti-lysozyme idiotypes: early antibodies did not display the predominant anti-hen eggwhite lysozyme idiotype (IdX-HEL), whereas late antibodies all displayed IdX-HEL. Furthermore, individual late hybridomas could each remove the entire anti-IdX-HEL activity by absorption, whereas early hybridomas could not. The epitope specificities of the hybridomas in both the early and late populations were heterogenous. We conclude that epitypic specificity in the response to HEL is determined independently from idiotypic specificity and that the predominant idiotype is selected for during the maturation of the anti-lysozyme response.