Structure of primary anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibodies in normal and idiotypically suppressed C57BL/6 mice

Analysis of somatic mutation and class switching in naive and memory B cells generating adoptive primary and secondary responses

Clonal progeny of naive B cells (producing a primary antibody response) and of memory B cells (producing a secondary response) were identified in a cell transfer system. Primary response clones are typically derived from IgM precursors and express unmutated V regions. Multiple isotype switches occur in these clones. Secondary response clones derive from IgG1 precursors and express highly mutated V regions. Additional switches do not occur. With one exception, there was no evidence for somatic mutation during clonal expansion. The generation of mutated memory cells may thus represent a distinct differentiation pathway. Evidence is presented that, in this pathway, mutants that have lost antigen binding specificity but that remain available for stimulation by a different antigen arise upon antigenic stimulation.

Isogeneic monoclonal antibodies against anti-alpha(1----3)dextran idiotypes. I. Isotypes, idiotope specificity and representation of idiotopes in antisera from mice of various genetic constitutions

Eight isogeneic anti-idiotypic hybridomas were raised against BALB/c myeloma protein MOPC 104E and one against J558. Both myelomas react specifically with the alpha(1----3) glucosidic linkage of dextran B1355 fraction S (Dex). Six anti-MOPC 104E proteins were IgG1, one was IgG2b and one IgM. The anti-J558 protein was IgG1. Competitive interactions of the anti-idiotopes and antigen with anti-Dex proteins were measured. Dex itself was effective, but also an alpha(1----3) glucosidic heptasaccharide (N7-CHO). In order to assess the anti-idiotope specificity of hybridoma proteins, three anti-Dex molecules were used: MOPC 104E, J558 and hybridoma protein Hdex14. These differed from each other in VH amino acid positions 54-55, or 100-101, respectively. By their serological reaction pattern our anti-idiotope proteins could be divided into 3 groups: cross-reactive, partially cross-reactive and strictly specific for the immunogen. The latter ones were in the majority, and were called "private", in contrast to the cross-reactive "public" anti-idiotopes. The serological pattern was followed, in general, by the mouse-to-mouse distribution of idiotopes in physiological anti-Dex sera. Public idiotopes were closely correlated in their expression with anti-Dex activity. "Private" idiotopes showed no correlation, and displayed a characteristically high degree of fluctuation from mouse to mouse. Among the different mouse strains that were compared with respect to idiotope expression in anti-Dex sera, two stand out: C57BL-Igha, which carries chromosome 12 of BALB/c, (as selected through allotype) on the C57BL/6 genome, and BALB-Ighb, dex+, a recombinant in chromosome 12 linking the dex+ trait from BALB/c to the CH allotype from C57BL/6. The latter strain expressed significantly more of the private idiotopes than the former. This observation is discussed in terms of the position effect of classical genetics and network concepts.

Induction of chronic idiotype suppression by ligands binding to the variable (not the constant) region of the idiotypic target

It was previously shown that in C57BL/6 mice chronic suppression of an idiotypically defined subset of lambda 1 chain-bearing anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibodies is achieved by neonatal administration of allogeneic monoclonal anti-idiotope antibodies reactive with this subset, or by NP coupled to mouse immunoglobulin. The present data show that isologous monoclonal anti-idiotope antibodies have the same effect. In contrast, antibodies against constant region determinants of lambda 1, mu or delta immunoglobulin chains failed to induce chronic suppression of the same antibody subset. Furthermore, the effect of the anti-idiotope antibodies was neutralized by idiotypic antibodies of the IgG1 class, injected before or together with the anti-idiotype. These results suggest that the mere complexing of idiotypic molecules on the B cell surface or in the circulation is insufficient for the induction of chronic idiotype suppression. In the present system, induction appears to require the binding of a ligand to idiotype-bearing receptor V regions, expressed on the surface of B (or T?) cells.

Clonal recruitment and somatic mutation in the generation of immunological memory to the hapten NP

The nucleotide sequences of the variable regions of lambda 1 chain bearing anti-NP antibodies from the secondary response of C57BL/6 mice were determined. The data indicate that the V186.2 VH gene which dominates the primary anti-NP response is expressed in nine out of 10 secondary response antibodies and is extensively mutated. In the V lambda 1 regions somatic mutations are less frequent. While point mutations predominate, there is suggestive evidence for two conversion events, one involving a one-codon deletion. Most, but not all, secondary response antibodies have a higher affinity (up to 10-fold) for the hapten than is seen in the primary response. The increase in affinity correlates with 'parallel' mutations in CDRs of H and L chains, likely to play a role in hapten binding. The analysis of VDJH rearrangements demonstrates that the secondary response lambda 1 chain-bearing antibodies are produced by a diverse set of B cell clones, which are only rarely expressed in primary responses. These clones are characterized by N-sequence-mediated heterogeneity in the 3' half of CDR3, where the germ line sequence of the D element DFl16.1 predominates in primary response antibodies. The antibodies analyzed in this and in previous work were isolated from idiotypically suppressed mice in order to evaluate whether, intraclonally, idiotype suppression selects antibody mutants into the memory pool, through suppression of the wild-type. A selection of this type was not detectable. However, idiotype suppression may control the pattern of clonotypes expressed in the primary versus the secondary response.

The T lymphocyte response to syngeneic lambda 2 light chain idiotopes. Significance of individual amino acids revealed by variant lambda 2 chains and idiotope-mimicking chemically synthesized peptides

In the present study we have investigated the structure of the helper T cell (Th)-defined idiotope (Id) of myeloma protein 315 lambda 2 light chain (lambda 2(315] in BALB/c (H-2d) mice which carry a high-responder immune response gene for this Id. Three peptides were synthesized which spanned the third hypervariable region (HV3) of lambda 2(315): peptides 88-99, 94-108 and 91-108. Only peptide 91-108 was capable of eliciting carrier-specific Th that recognized M315 or free lambda 2(315). These Th did not recognize lambda 2(5-7) chain which differs from lambda 2(315) at 4 positions in this region; these are Tyr94, Ser95, Thr96, Tyr98 for lambda 2(5-7) and Phe94, Arg95, Asn96, Phe98 for lambda 2(315). Immunization with peptide analogues revealed that substitution of Tyr for Phe94 was compatible with Id-lambda 2(315) mimicry, but substitution of Ser for Arg95 or Thr for Asn96 destroyed the Th-recognized Id. Furthermore, Th primed with lambda 2(5-7) chain did not cross-react with lambda 2T952; these lambda 2 chains only differ from each other at positions 98 and 99 at the V lambda 2-J lambda 2 junction. The data indicate that individual amino acids of short peptide segments are critical for Th-recognized Id of the lambda 2 HV3 loop and V lambda 2-J lambda 2 junction. Furthermore, the immunogenicity of a small peptide suggests that the carrier (lambda 2)-specific Th recognize Id that have been processed by antigen-presenting cells (APC). This implies the existence of two categories of "internal images" of foreign or of self antigens: (a) serologically defined and (b) T lymphocyte defined. We propose that as a rule, Id processing by APC, including B cells, destroys the first and reveals the second category. The possible physiological function of these Id-specific T cells in network interactions with B cells is discussed.

The bulk of endogenously produced IgG2a is eliminated from the serum of adult C57BL/6 mice with a half-life of 6-8 days

The concentration of IgG2a in the serum of C57BL/6 mice suppressed for the production of IgG2a was measured over a period of 3 months after suppression. The elimination of a minimum of 96% of the endogenous IgG2a molecules from the serum follows an exponential decay with a half-life of 6-8 days. A monoclonal IgG2a antibody injected into suppressed or normal mice is eliminated from the serum in the same fashion. We conclude that there are few, if any, "long-lived" IgG2a molecules present in the serum of C57BL/6 mice under physiological conditions.

Altered repertoire of endogenous immunoglobulin gene expression in transgenic mice containing a rearranged mu heavy chain gene

C57BL/6 mice transgenic for a mu heavy chain gene, the VDJ region of which came from the BALB/c hybridoma 17.2.25, expressed high levels of antibody carrying determinants specific for the transgene (idiotypes). The individual antibodies made by hybridomas from transgenic mice, however, were generally encoded by endogenous genes; in most cases the transgene was present but not expressed. The endogenous, idiotype-positive antibodies had heavy chains that were notable for the high frequencies of JH4 (as in the transgene) and VH segments from the VH81X family (unrelated to the transgene). The expression of endogenous genes mimicking the idiotype of the transgene suggests that a rearranged gene introduced into the germ line can activate powerful cellular regulatory influences.

Regulation of the immune response. II. Concomitant idiotope-specific enhancement and suppression can result in a phenotypically normal response

Idiotope-specific immunoenhancement or suppression was induced in C57BL/6 mice by the injection of physiological amounts (100 ng-10 micrograms) of monoclonal anti-idiotope antibody. As previously described, nanogram doses enhanced idiotope expression while a 10-micrograms dose of anti-idiotope antibody induced the activation of a population of Thy 1.2+, Lyt 1-, 2+ suppressors. Both positive and negative regulatory activities were confined to the non-mu, idiotope+ compartment of the plaque-forming cell response. Administration of intermediate doses of anti-idiotope antibody resulted in an immune state indistinguishable from that of naive mice. This apparently normal response was in fact the product of a simultaneous activation of balanced enhancing and suppressive activities. When treated with anti-Lyt 2 or Lyt 1 and complement, spleen cell populations taken from such phenotypically "naive" mice revealed latent idiotope-specific immunoenhancement or suppression, demonstrating the components of a functional regulatory equilibrium.

Several V genes participate in the early phenyloxazolone response in various combinations

Seventeen monoclonal anti-2-phenyloxazolone antibodies from the early (day 7) primary response were partially sequenced with an mRNA method. Ten antibodies expressed the VH-Ox1 gene. The remaining seven express at least four but probably six different germ-line VH genes belonging to Dildrop's groups 1, 5, 6 and 7 (Immunol. Today 1984. 5: 85). Two of them have been met before in other antibodies, one (group 6) in J606 and the other (group 7) in antibodies to the influenza virus hemagglutinin. Eleven kappa chains were partially sequenced and five of them (all VH-Ox1 antibodies) express the V kappa-Ox1 gene. One expresses another germ-line gene of the V kappa-Ox1 family, one the V kappa 89.4 gene, three the V kappa 45.1 gene and one a new V kappa gene. The V kappa 45.1 gene was found to form anti-phOx antibodies with two new VH genes. The frequency of somatic mutations in day 7 antibodies was estimated by comparing germ-line sequences and antibody sequences. It is low (one mutation per 2500 nucleotides sequenced), twenty times lower than in antibodies obtained a week later. Two anti-idiotype antisera (495 and 260) are useful in the typing of monoclonal antibodies. 260 bound only to antibodies coded by both VH-Ox1 and V kappa-Ox1 genes. 495 bound strongly to antibodies coded by the VH-Ox1 gene and weakly to antibodies coded by the (related) VH101 gene regardless of the light chain partner.

The T-cell-independent immune response to the hapten NP uses a large repertoire of heavy chain genes

Hybridomas generated from C57BL/6 mice immunized with the hapten NP coupled to ficoll, a T-cell-independent carrier, produce monoclonal antibodies that use a large repertoire of VH regions and light chains. This contrasts with the homogeneity of the strain-specific response to NP observed with T-cell-dependent carriers, where most of the antibodies use a single VH region, V186.2, in combination with the lambda-1 light chain. There is no evidence for somatic mutation in any of the sequenced regions of the antibodies generated by NP-ficoll. Thus T cell participation is required for the homogeneity of the strain-specific hapten response, and probably for somatic mutation as well.

Helper T cells reacting to idiotype on IgG but not IgM

Immunization with an IgG1 but not an IgM monoclonal anti-NP (4-hydroxy-3-nitrophenyl acetyl) antibody induced idiotype-recognizing T helper cells, although these two antibodies carry the same variable regions. The T cells appear to react to an idiotype on the IgG1 but not the IgM antibody. They selectively enhance the expression of that idiotype in the IgG1 fraction of an in vitro anti-NP response.