A mendelian idiotype is demonstrable in the heteroclitic anti-NP antibodies of the mouse

Joining-chain (J-chain) negative mice are B cell memory deficient

The systemic immune response of joining-chain (J-chain)-deficient mice (J(-/-) mice) on a C57BL/6 background against the hapten 4-hydroxy-3-nitrophenyl (NP) was analysed. While primary IgG responses to the hapten were similar to those observed in WT control animals, secondary immune responses were compromised both at the level of serum IgG and the number of responding B cells. The repertoire switch from lambda to kappa in secondary immune responses was diminished in J(-/-) mice. The number of somatic mutations introduced in the V(H) 186.2 gene during the primary immune response was reduced, while the frequency of affinity-increasing mutations in position 33 was similar. By adoptive transfer experiments it could be shown that the compromised secondary immune response was transferred with T cells from J(-/-) mice. Thus, J-chain-deficient mice have a selective defect in T helper cell function during B cell immune responses, resulting in a deficiency in the formation of B cell memory.

Canonical germinal center B cells may not dominate the memory response to antigenic challenge

Spleen and bone marrow (BM) are the major sites of antibody production and anamnestic response in systemically immunized mice. We examined the VDJ segment repertoire of antibody plaque-forming cells (APFC) in those two sites in the course of antibody responses to the hapten nitrophenyl (NP). Individual IgG APFC expressed any one of 10 V(H) segments of the V186.2/V3 (J558) gene family: 186.2, 102, 23, C1H4, 165.l, CH10, 3, 593.3, 24.8 and 671.5. The majority of cells in both spleen and BM expressed the V186.2 gene joined to a D segment with Tyr95. During a 2-month period after a single immunization, the V186.2(+) APFC in BM accumulated 3 times as many somatic mutations than splenic APFC (average 8.5 versus 3 mutations/V(H)); this process was T(h) dependent as shown by in vivo depletion of CD4(+) lymphocytes. However, the V186.2(+) APFC in both spleen and BM shared a recurrent W33L replacement, indicating their common origin from germinal centers. The APFC expressing the other (analogue) V(H) segments were evenly represented in the spleen and BM, but they accumulated few, if any, mutations. The anamnestic V186.2(+) APFC were highly mutated both in the spleen and BM; they represented a new and unexpected clonotype. The V/D segments were joined by Gly95 instead of Tyr95, the W33L was absent and a new shared K58R replacement appeared. The APFC expressing the 'analogue' V(H) genes comprised approximately 20% of the anamnestic response and did not accumulate more mutations, but their affinities were in the range of the memory V186.2(+) cells. These data suggest that the late primary and secondary responses to a hapten may be born by different B cell lineages, and that some clonotypes may reach the memory pool without an extensive mutation and expansion.

Kinetic and genetic bases for the heteroclitic recognition of mouse cytochrome c by mouse anti-pigeon cytochrome c monoclonal antibodies

The B lymphocyte response to pigeon cytochrome c (CYT) in BALB/c mice was previously shown to initiate as a heteroclitic response specific for the self antigen mouse CYT. As the immune response progressed, the mAb that were produced became less heteroclitic and often bound pigeon CYT with higher affinity than they bound mouse CYT [Minnerath, J. et al., 1995. Proc. Natl. Acad. Sci. USA 92, 12379-12383]. To study the basis for heterocliticity and its loss in this system, the H and L chain amino acid sequences of anti-pigeon CYT mAb obtained from the primary and secondary Ab responses were first compared. The most frequent somatic mutations and Ig gene joints were then introduced into an engineered single-chain Fv (scFv) that expressed the germline-encoded V(H) and V(L) amino acid sequences. The effects of those changes on the on- rate, off-rate, and affinity constants in binding both mouse and pigeon CYT were determined by surface plasmon resonance. In this system, the heterocliticity of primary mAb was largely due to a decreased on-rate constant for binding pigeon CYT relative to mouse CYT. Various combinations of the three frequently occurring H chain somatic mutations (H31, H56, and H58) increased the on-rate constant to maximal levels. Only one of the mutations (H58) decreased the off-rate constant when in combination with the other mutations and the effect of H58 was greater for scFv binding mouse CYT than pigeon CYT. Consequently, the mutated scFv and many secondary mAb remained heteroclitic, although their affinities for pigeon CYT increased. Secondary mAb that were no longer heteroclitic expressed non-canonical amino acid sequences in the V(H)-D-J(H) joint in the context of the canonical V genes or expressed different V genes. In addition to providing insight into the molecular basis for heterocliticity, our findings confirm that both faster on-rate and slower off-rate constants are favored during affinity maturation of the Ab response.

Failure to demonstrate public idiotypes on cytolytic cells with specificity for NP-coupled syngeneic cells

We have investigated whether cytolytic cells specific for hapten-coupled syngeneic cells have the same public idiotype as serum antibodies against the same hapten, NP-aminocaproyl (NP-cap). Anti-NP-cap antibodies of C57BL mice possess a public idiotype that can be detected by antisera against the whole V region of the antibody molecule or against the VH domain. Neither reagent had an effect on the cytolytic response either when they were used to sensitize the effector cells for complement killing or when used at high concentrations in the culture medium during the secondary stimulation in vitro.

Subtle differences in antibody responses and hypermutation of lambda light chains in mice with a disrupted chi constant region

Analysis of lambda light chain use in normal mice is made difficult by the dominant chi light chain repertoire. We produced mice rendered deficient in chi light chain expression by gene targeting and focused on questions concerned with the generation of lambda light chain diversity. Whilst these mice compensate the chi deficiency with increased lambda liters, and their Ig level is therefore not significantly reduced, they show major differences in immunization titers, germinal center (GC) development and somatic hypermutation. After immunization, using antigens that elicit a restricted IgL response in normal mice, we obtained in the chi-/- mice elevated primary antibody titers but a subsequent lack in titer increase after repeated antigen challenge. Analysis of the Peyer's patches (PP) revealed a dramatically reduced cell content with rather small but highly active GC. Flow cytometric analysis showed different cell populations in the PP with enriched peanut agglutinin (PNA)hi/CD45R(B220)+ B cells, implying that the apparent compensation for the lack of lambda light chain expression involves the GC microenvironment in cell selection, the initiation of hypermutation and high affinity expansion. The three V lambda genes, V1, V2 and Vx, are mutated in the GC B cells, but show no junctional diversity. In contrast, a reduced rate of V lambda hypermutation is found in the hybridoma antibodies, which appears to reflect a selection bias rather than structural constraints. However, mechanisms of somatic mutation and specificity selection can operate with equal efficiency on the few V lambda genes.

A map of VH genes located next to the DH region in the Igh locus of two congenic Igh-recombinant mouse strains

A new congenic mouse strain (C57BL/6-Igh-Vb-Ca) with a recombinant chromosome 12 is described. It carries the Igh-1a allele, but shows the serological characteristics of C57BL/6 when analyzed for idiotype expression with respect to the antigens dextran and (4-hydroxy-5-iodo-3-nitrophenyl)acetyl (NIP). We analyzed liver DNA from one animal for restriction fragment length polymorphism by hybridization to probes detecting members of nine VH gene families and DH segments, and compared it to DNA from animals carrying the nonrecombinant haplotypes Igha and Ighb, respectively. The breakpoint of recombination maps to the region carrying members of VH gene families VGAM3.8, PC7183 and Q52. The CB8KN strain which according to the serological analysis carries a recombinant Igh locus (Igh-Va-Cb) on BALB/c background was also analyzed. In this strain the breakpoint of recombination again maps to the region carrying members of VH gene families VGAM3.8, PC7183 and Q52. Our results show that the VH genes of families PC7183 and Q52 are interspersed and map to the region next to the DH locus. At least one gene from the VGAM3.8 family also maps to this region in the Igha and the Ighb haplotype.

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.

Isotype of protective anti-Salmonella antibodies in experimental mouse salmonellosis

Mice and a rabbit were immunized with heat-killed Salmonella typhimurium bacteria or with an O-4,12 antigen-specific octasaccharide-protein conjugate. Immunoglobulin isotypes of the antisera were tested for their capacity to protect mice against experimental salmonellosis. Antibodies of immunoglobulin M + A isotypes were more protective than the immunoglobulin G antibodies in each of the two pools of mouse sera. The same protective pattern was also seen with a rabbit antiserum elicited by the artificial octasaccharide-protein conjugate, i.e., with antibodies with the exclusive specificity for the O-4,12 antigen determinants of S. typhimurium.

Genetic control of the murine IgM plaque-forming cell response to type III pneumococcal polysaccharide

The direct 5-day plaque-forming cell response of different inbred mouse strains to pneumococcal polysaccharide type III (SSS-III) varied from more than 10,000 per spleen, in BALB/c mice, to less than 2000 in C57BL mice. Responses of Igh congenic and recombinant inbred lines bearing different combinations of BALB/c and C57BL genes indicate that two or more gene loci are involved in controlling high or low responses. At least one is in the Igh-V region since BALB/c, BAB-14, and CB-8 KN mice (Igh-Va) had two to four times higher responses than CB-20 and CB-16 KN mice (Igh-Vb). Other gene loci must be involved, but nothing can be said about them at present.

Heterogeneous and monoclonal helper T cells induce similar anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibody populations in the primary adoptive response. II. Lambda light chain dominance and idiotope expression

When the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP) is presented on different carrier molecules, different anti-NP antibody responses are stimulated. On stimulation with NP-lipopolysaccharide (LPS) [T-independent type 1 (TI-1) antigen] kappa + antibodies are the major population, whereas on stimulation with NP-Ficoll [T-independent type 2 (TI-2) antigen], NP-keyhole limpet hemocyanin (KLH) or NP-chicken gamma globulin (CG) [T-dependent (TD) antigens], lambda 1+ antibodies dominate. The relative contribution of idiotopes Ac38 or Ac146 to the lambda 1+ anti-NP response was also different on comparison of TI-1 with TI-2 or TD anti-NP responses. We investigated whether light chain- or idiotype-specific T cells are responsible for these differences. Analysis of the anti-NP response of nude mice after immunization with NP-Ficoll showed lambda 1 dominance. Likewise primary adoptive transfer experiments using carrier-specific T cell lines to reconstitute the TD anti-NP response to NP-KLH or NP-CG, showed that help from carrier-specific T cells alone is capable of stimulating the characteristic lambda 1 dominant response. No significant difference could be found in the levels of Ac38 and Ac146 idiotope expression between mice reconstituted with splenic T cells and those reconstituted with T cell lines. These results suggest that light chain- or idiotype-specific T cells are required neither for the production of lambda 1 light chain dominance, nor for the appearance of idiotopes characteristic of the primary anti-NP response. The possible reasons for differences seen in both light chain and idiotope expression between primary anti-NP responses to the TI-1 antigen NP-LPS and those to TD or TI-2 antigens are discussed.

Idiotypes of anti-major histocompatibility complex antibodies

Our studies to date indicate that treatment with anti-idiotype to monoclonal anti-MHC antibodies can markedly influence the repertoire of anti-MHC antibodies expressed. The antibodies discussed here appear to represent two classes, one of which is public, probably representing expression of a germ line gene, and the second of which probably represents either a somatic variant of a germ line gene or one of a very large number of germ line genes devoted to the same specificity. In either case, this class of idiotype arises only rarely following antigen, but is readily induced by anti-idiotype treatment. There may indeed exist a third class of anti-MHC monoclonal antibodies representing distant somatic diversification from a germ line gene. Our only indication of this so far is that certain idiotypes are only induced after multiple boosts with anti-idiotypes rather than a single treatment. This finding, however, may reflect again the enormous number of different ways in which anti-MHC antibodies to the same nominal specificity can be produced. Finally, our results in adoptive transfer systems indicate that manipulation of idiotype expression by anti-idiotype treatment probably involves a complex pathway of cellular interactions. If, as we expect, these intercellular interactions involve idiotype and/or anti-idiotypic receptors, they should provide a model for mechanistic studies of the in vivo immune network.

Idiotypic and fine specificity analysis of a (4-hydroxy-3-nitrophenyl)acetyl (NP)-specific suppressor T cell hybridoma at the level of cell surface structures, isolated receptor material and functional suppressor factor

The (4-hydroxy-3-nitrophenyl)acetyl (NP)-specific T suppressor cell hybridoma 7C3-13 was established by fusing splenic B10.BR T cells enriched on NP-coated petri dishes with the AKR thymoma BW5147. 7C3-13 was selected by anti-NPb idiotypic and anti-I-Jk antibodies in microcytotoxicity tests. The hybridoma expressed H-2k, I-Jk, Qa-1, Thy-1.1 as well as idiotypic (binding site-related) and framework Ig VH determinants, while it was negative for I-A, I-E/C, Thy-1.2, Lyt-1, Lyt-2 and Ig constant region determinants. Hapten-binding receptor material could be isolated from 7C3-13 cells on NP-coupled nylon nets and functionally active T suppressor factor (TsF) could be extracted from the hybridoma. Both types of soluble molecules express NPb idiotype, but the TsF carries I-J determinants in addition while the isolated receptors do not. The molecular weight of the isolated receptor material is 80 000, that of the TsF activity is 27 000 and 57 000-64 000, respectively. We thus were able to show that NP-binding molecules can be obtained in the form of cellular surface receptors, isolated receptor material and extracted TsF from one and the same, monoclonal, cell source.

LPS greatly enhances the antibody response to hapten-polysaccharide conjugates, but not to hapten-protein conjugates

In confirmation of earlier findings, we observed that an injection of bacterial lipopolysaccharide (LPS) into mice caused a considerable increase in the serum concentrations of IgM and IgG (total Ig rose three- to four-fold in 7 days), and a corresponding increase in the concentrations of "natural" anti-(3-iodo-4-hydroxy-5-nitrophenyl) acetyl (NIP) and anti-trinitrophenol (TNP) antibodies. Our main purpose was to determine what effect LPS had on antigen-dependent responses. Hapten conjugates of a polysaccharide and of proteins were used as antigens. Hapten-protein conjugates induced a strong anti-hapten antibody response (up to 1 mg/ml of anti-hapten antibodies on day 7). Hapten-polysaccharide conjugates induced only a meagre increase in anti-hapten antibodies from the pre-immunization level (maximal concentration 65 micrograms/ml on day 7). LPS, when injected with the antigen, greatly enhanced the antibody response to the hapten-polysaccharide conjugates (up to 2.6 mg/ml of anti-hapten antibodies on day 7). It had little effect on antibody responses to hapten-protein conjugates. The combination treatment had the same effect on immunoglobulin concentrations as LPS alone.

IgG subclass distributions in anti-hapten and anti-polysaccharide antibodies induced by haptenated polysaccharides

Mice were immunized with hapten [NIP, (4-hydroxy-5-iodo-3-nitrophenyl)acetyl or TNP (2,4,6-trinitrophenyl)] conjugates of Ficoll or pneumococcal polysaccharide type 14 (S14), and they were bled on days 10 or 14. Anti-hapten and anti-polysaccharide antibodies were determined from the sera or from fractions (IgM + IgA). IgG1, IgG2a, IgG3 or IgG2b separated by a gradual acid elution from protein A. Approximately one-half of both anti-hapten and anti-polysaccharide antibodies was found in the IgM + IgA fraction. The subclass distribution of the IgG antibodies was dependent on the antigenic determinants. Polysaccharide antibodies were mostly in the IgG3 fraction (36-62%) and in the IgG1 fraction (18-36%). Hapten IgG antibodies were mostly in the IgG1 fraction (38-74%): each of the other three subclasses contributed the average of 13%. These results provide the first evidence that antibodies to different determinants of one antigen have grossly different isotype distributions.

The expression of a set of antibody variable regions in lipopolysaccharide-reactive B cells at various stages of ontogeny and its control by anti-idiotypic antibody

An analysis is presented in which we measure the expression of a subset of antibody variable (V) regions in lipopolysaccharide (LPS)-reactive precursor B cells at various stages of ontogeny. The V regions were characterized by hapten (4-hydroxy-3-nitrophenyl)acetyl (NP)-binding specifity and/or expression of idiotypic determinants whose genetic basis had been explored in previous studies. Only V regions containing the V lambda 1 domain were considered: this allowed an unequivocal determination of idiotopes and reduced heterogeneity in the system essentially to the multiplicity of VH and D genes. It was found that approximately every fourth lambda 1-bearing LPS-reactive splenic B cell produces an NP-binding antibody. Approximately 1 in 40 lambda 1-bearing cells expressed an idiotope (Ac38) which is encoded by V lambda 1 and a set of related VH genes in combination with D and J elements. Of these cells, only a minority produce an NP-binding antibody and a few percent of the latter express a second idiotope (Ac146) which is known to be restricted to a subset of Ac38-positive, NP-binding humoral antibodies. All these frequencies are in good accord with previous analyses of anti-idiotope-induced antibodies in the serum. They can be easily accommodated into a simple model of random selection of VH genes in LPS-reactive B lymphocytes. The frequencies of the V regions under study were essentially the same in LPS-reactive B cells from spleens of adult and newborn animals and in LPS-reactive B cells generated from bone marrow pre-B cells in vitro. In the case of the latter cells the frequencies were independent of the absence or presence of T cells in the culture system. While we could thus detect, in naive mice, neither positive nor negative selection of the cells from the time of their generation in the bone marrow until their arrival in the periphery, negative selection is in principle possible: the presence of microgram amounts of anti-idiotope antibodies during maturation from pre-B to B cells specifically blocks the appearance of idiotope-bearing LPS-reactive cells in vitro. The potential physiological role of the latter effect in the sense of self-stabilization of the expressed antibody repertoire in ongoing immune responses and the possibility that frequency determinations in LPS-reactive B cells may be not representative for the repertoire expressed in the population of mature B cells is discussed.

Mouse IgG antibodies have subclass associated affinity differences

Subclasses of IgG were separated from pools of mouse sera by letting immunoglobulins absorb on protein A-Sepharose and by eluting with buffers of decreasing pH. Most donor mice were immunized with a conjugate of a hapten (NIP) and chicken gamma globulin 20 days previously. The results indicate that concentrations of IgG varied from 5.1 to 8.6 mg/ml in the pools of immune sera and was 3.0 mg/ml in one normal serum tested. One half of this was IgG1, ca. 20% of IgG2a and IgG2b each, and 10% IgG3 in the pools of BALB/c sera. IgG2a and IgG3 could not be separated from C57BL sera (due to allotype b), but their combined share of IgG appears to be higher than in BALB/c. Immune sera contained 0.5-1.6 mg/ml of anti-NIP antibodies. Of this 90-98% was IgG1 and the remainder was split between the other subclasses. Up to one half of the protein in the IgG1 fraction was anti-NIP antibody. This surprising finding was confirmed by demonstrating that nearly 50% of the u.v.-light absorption was specifically removed by a NIP-immunosorbent. Subclass-associated affinity-differences were observed. IgG1 anti-NIP had a greater average affinity than IgG2a anti-NIP antibodies. The difference was ca. 1.5-fold when the equilibrium dialysis was focusing on the high-affinity bracket of the total population (concentration of free hapten 16-200 nM). At higher hapten concentrations the trend was the same but the data are fewer. Antibodies in subclasses IgG2b and IgG3 appear to share the lower affinity of IgG2a.

Antigenic relationships of murine coronaviruses

Two serological tests were used to examine the antigenic relationships between murine hepatitis viruses that cause different diseases in mice. Antisera prepared by immunization of mice with the individual viruses were tested for their ability to neutralize both the homologous immunogen and the other viruses. By a plaque reduction neutralization test, each antiserum was found to be specific for the immunizing virus; however, there was substantial cross-reactivity, indicating the viruses were closely related. By kinetic neutralization, two of the viruses tested, MHV-JHM and MHV-2, were found to be antigenically distinct. MHV-3 and MHV-A59 were found to be antigenically very similar but distinct. These data show that kinetic neutralization is a more precise method for determining the antigenic relationships between murine coronaviruses.

The immune response against anti-idiotope antibodies. I. Induction of idiotope-bearing antibodies and analysis of the idiotope repertoire

In the present analysis we dissect the idiotype repertoire, independently of hapten-binding specificity, by immunizing different strains of mice with cross-linked monoclonal anti-idiotope antibodies against antibody B1-8. B1-8 is a monoclonal antibody with specificity for the hapten (4-hydroxy-3-nitro-phenyl)acetyl (NP) and carries a germ line gene-encoded variable region. The results demonstrate that the expression of B1-8 idiotopes and their association with each other and with NP-binding specificity are strain-specific. Certain idiotopes are expressed on antibodies differing in antigen-binding specificity, whereas one of the idiotopes appears strictly associated with NP-binding antibodies. The genetic analysis provides strong evidence that the strain specificity of the idiotope repertoire is a result of V region polymorphism in the mouse.

The protective capacity of immune sera in experimental mouse salmonellosis is mainly due to IgM antibodies

Passive immunization was used to protect mice against a general infection caused by Salmonella typhimurium and our purpose was to compare the protective capacity of different immunoglobulin isotypes (classes and subclasses). Three antisera were studied, one pool of mouse serum against the envelope of rough bacteria, and two rabbit sera against smooth bacteria. Three different methods were used to separate isotypes. The consistent finding was that only IgM antibodies protected efficiently. A unit of IgG antibodies had an effect that was 1/50th of the IgM effect or less. This effect could have been due to a contamination by IgM. IgA appears to be non-protective like IgG. In two of the antisera a considerable proportion of protective antibodies were against a defined antigenic determinant (anti-0-4,5 or anti-0-9). IgG antibodies of these sera measured by the solid phase assay were also predominantly anti-0-4,5 or anti-0-9, respectively. This argues that the failure of IgG antibodies to protect cannot be explained by assuming that unlike IgM antibodies they are directed against "non-protective" determinants. We conclude that the observed difference between the protective capacities of IgM and IgG antibodies is due to C-region differences between the mu- and gamma-chains.

Cross-reactivity of the NPa and NPb idiotypic responses of BALB/c and C57BL/6 mice to (4-hydroxy-3-nitrophenyl)acetyl (NP)

A comparative antigenic analysis was carried out to determine whether cross-reactivity exists between the major idiotypic responses to (4-hydroxy-3-nitrophenyl)acetyl (NP) in BALB/c and C57BL/6 mice. Extensive cross-reactivity exists between the NPa (BALB/c) and NPb (C57BL/6) allotype-linked idiotypic responses to NP. The cross-reactive determinants of the NPb idiotype are confined to one particular group of NPb-positive monoclonal antibodies. The extent of cross-reactivity between this group of C57BL/6 antibodies and idiotype-positive monoclonal antibodies of BALB/c is so great that they cannot be readily distinguished as NPb- or NPa-positive antibodies with polyclonal anti-idiotypic reagents. That this cross-reactivity is not unique to monoclonal antibodies was confirmed by the demonstration of these cross-reactive determinants in the immunesera of individual BALB/c and C57BL/6 mice. Additionally, evidence was obtained from these experiments and from earlier ones from this laboratory which suggests that the BALB/c idiotypic response to NP-protein conjugate is more homogeneous than the C57BL/6 idiotypic responses.

T-cell proliferative response to hapten-modified self-immunoglobulins: recognition of conjugate-specific determinants

(4-Hydroxy-3-nitrophenyl)acetyl (NP)-modified BALB/c immunoglobulins were used as the immunogen for induction of a proliferative response in BALB/c mice. As is true for responses to other soluble antigens, proliferation was dependent on Lyt-1 cells and histocompatible radioresistant accessory cells. Lyt-1 cells directed against NP-modified self immunoglobulin are specific for the immunizing hapten NP. However, they do not recognize hapten per se. Rather, they see complex determinants comprised of both the hapten NP and the immunoglobulin self-carrier. Distinct specificities were created by coupling the same hapten to different monoclonal BALB/c antibody molecules or by attaching the hapten to the immunoglobulin self-carrier via a spacer molecule. It is proposed that determinants created by attaching haptens to self-immunoglobulin molecules are similar to those recognized by anti-idiotypic T cells.

Synthesis of lambda 1, lambda 2, and lambda 3 light chains by mouse spleen B cells

To determine whether the infrequency of immunoglobulins with lambda 3 light chains is due to a corresponding scarcity of lambda 3 B cells, the production of the various lambda chain subtypes (lambda 1, lambda 2, and lambda 3) by normal spleen cells was compared. The results showed that lambda 1, lambda 2, and lambda 3 chains are produced in a ratio of about 1.0: 0.7 : 0.3, respectively. The argument is made that lambda 1, lambda 2, and lambda 3 B cells exist in the same ratio. Results obtained with neonatal and nude mouse spleen cells suggest that these small differences are not due to stimulatory effects of environmental antigens or regulatory T cells. The much greater disparity in the abundance of lambda subtypes in various antibody responses and serum Ig suggests that lambda 1 B cells may be more likely than lambda 2 or lambda 3 B cells to differentiate into antibody-secreting plasma cells.

A common idiotype on SJL and C57BL/6 anti-(4-hydroxy-3-nitrophenyl) acetyl antibodies and its relationship with lambda chain production

Hybridoma cell lines secreting antibodies specific to (3-nitro-4-hydroxyphenyl) acetyl (NP) were generated by fusion of NP-immunized SJL spleen cells with the SP2/0 cell line. One hybridoma (N-hybridoma) anti-NP antibody (mu, lambda2) was found to partially inhibit (35-40%) the binding of the predominant idiotype in primary C57BL/6 anti-NP antibodies (NPb). Iodinated hybridoma antibody could be completely bound with anti-idiotypic antiserum made against either specifically purified C57BL/6 anti-NP antibodies, SJL anti-NP antibodies, or N-hybridoma antibody. The idiotypic specificities defined with anti-idiotypic antiserum made against N-hybridoma antibody were termed NP-1 idiotype. Strain distribution and genetic mapping studies indicate that the gene(s) controlling the production of NP-1 idiotype is closely associated with Igh-1b and Igh-1e alleles and mapped within the same chromosomal segment that controls the synthesis of NPb idiotype. However, unlike NPb idiotype, the expression of NP-1 idiotype is not influenced by the gene(s) that control lambda1 chain synthesis. Thus, SJL mice that produce low or undetectable levels of NPb idiotype due to a defect in lambda1 chain production express high levels of NP-1 idiotype. Specifically purified C57BL/6 and SJL anti-NP antibodies fully express NP-1 idiotype, the level of which correlates with the level of lambda2 chain-bearing molecules. Nonetheless, further experiments indicate that lambda1-bearing anti-NP antibodies can express extremely weak NP-1 idiotypic cross-reactivity.

Hapten-specific T cell responses to 4-hydroxy-3-nitrophenyl acetyl. XII. Fine specificity of anti-idiotypic suppressor T cells (Ts2)

The fine specificity of anti-idiotypic, effector-phase suppressor T cells (Ts2) induced by the intravenous injection of syngeneic spleen cells covalently coupled with the 4-hydroxy-3-nitrophenyl acetyl (NP) hapten was studied in an in vitro plaque-forming cell system. By comparing the ability of these suppressor cells to bind monoclonal anti-NP antibodies that express different levels of serologically detected NPb idiotypic determinants, it was shown that anti-idiotypic suppressor T cells do not recognize the predominant NPb idiotypic determinants that are defined by serologic analysis. The implications for the possible expression and/or recognition of different sets of idiotypic determinants on T and B cells are discussed.

Characterization of the NPa idiotype through the analysis of monoclonal BALB/c anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibodies

Spleen cells from BALB/c mice were fused with the nonsecreting myeloma line X63.Ag8.6.5.3 seven days after immunization with NP-CG (4-hydroxy-3-nitrophenyl) acetyl-chicken gamma-globulin. The hybrid cell lines obtained were analyzed for heavy and light chain distribution, fine specificity, and idiotype. The majority of monoclonal antibodies possessed either gamma 1 or mu chains. The distribution of L chains among these antibodies was approximately half lambda and half kappa . Thirteen monoclonal antibodies were grown as ascites tumors in mice. Examination of their fine specificity patterns showed that all of the lambda antibodies are heteroclitic and have similar fine specificity patterns. Five of the seven kappa antibodies are also heteroclitic, but their fine specificity patterns are more heterogeneous than those of the lambda antibodies. Polyspecific anti-idiotypic sera directed against pooled primary serum antibody (R a-NPa) or against individual monoclonals were used for idiotypic characterization of the monoclonal antibodies. The Ra-NP bound all of the lambda antibodies but none of the kappa antibodies suggesting that the kappa antibodies may be much more heterogeneous and were therefore not recognized in the presence of the more homogeneous lambda antibodies. Further idiotypic analysis demonstrated that the lambda antibodies, although no two are identical, are a very homogeneous group of antibodies which cross-react with one another but not with the kappa antibodies. Some, but not all, of the kappa antibodies cross-react with each other although none are cross-reactive with the lambda antibodies. Because the lambda-associated idiotype is recognized by the R a-NPa and its characteristics are similar to that of the C57BL/6 major idiotype (NPb), it is referred to as NPa. There may be a second major idiotype associated with at least some of the kappa antibodies.

Idiotypes of anti-Ia antibodies. I. Expression of the 14-4-4S idiotype in humoral immune responses

The idiotype of a mouse monoclonal anti-I-E antibody, 14-4-4S, has been studied using a heterologous anti-idiotypic reagent. This antibody recognizes Ia. 7, an antigenic specificity present in all strains expressing a product of the I-E subregion. Expression of the 14-4-4S idiotype in humoral immune responses was analyzed by an idiotype-specific enzyme-linked immunosorbent assay system. The idiotype was readily detectable in C3H.SW anti-C3H alloantisera, the same immunization combination from which the hybridoma was derived. Absorption analysis demonstrated the anti-I-E specificity of the idiotype-positive molecules in these alloantisera. Penetrance of idiotype expression was high among individual C3H.SW immune mice (9 of 10 tested). To examine genetic requirements for idiotype expression, an immunization was performed using as responders CWB mice, congenic with C3H.SW but differing at the heavy chain allotype loci. Immune sera of individual CWB mice contained very little or no idiotype, demonstrating that levels of idiotype expression are influenced by allotype-linked genes, although the influence of other genes has not been ruled. The 14-4-4S idiotype therefore represents a shared idiotype of anti-Ia antibodies and provides opportunities for analysis of the idiotypes of cellular receptors for the corresponding Ia antigen.

Linkage and recombination of VH gene markers, Np and Nb, in recombinant inbred strains of mice

Mice of 24 recombinant inbred (RI) strains of the BXD series were typed for Igh markers, Np and Nb. In 22 strains these markers were concordant with the allotype (10 DBA/2-like and 12 C57BL/6-like). Strains BXD-20 and BXD-27 had a recombinant haplotype; their allotype was DBA/2-like but the Np and Nb characteristics were C57B/6-like.

Expression of an antigen receptor on T cells does not require recombination at the immunoglobulin JH-C mu locus

Considerable evidence has accumulated suggesting that the antigen receptor(s) on T cells is coded for by genes for the variable (V) region of the immunoglobulin heavy (H) chains. In B cells, a complete gene for the immunoglobulin VH region is formed by somatic recombination of VH and joining region heavy chain (JH) gene segments [through an intermediate diversity(D) region gene segment]. In an attempt to determine whether a complete immunoglobulin VH region is expressed on T cells that bear an antigen receptor, we analyzed the restriction map of the JH-C mu locus in genomic DNA from two cloned murine cytotoxic T-lymphocyte (CTL) lines specific for the x-ray-induced leukemia RL male 1. We found no rearrangement of the JH C mu locus in the CTL lines, indicating that the T-cell antigen receptor(s) in these CTLs is not coded for by a complete immunoglobulin VH gene formed by joining of VH, (DH), and JH genes. In addition, we determined that C mu genes on both chromosomes were present and that there was no rearrangement of the C alpha, C kappa, or lambda chain genes in these CTL cells.

Hapten-specific T cell responses to 4-hydroxy-3-nitrophenyl acetyl. IX. Characterization of Idiotype-specific effector-phase suppressor cells on plaque-forming cell responses in vitro

The ability of T suppressor cells, induced by the intravenous injection of 4-hydroxy-3-nitrophenyl acetyl (NP)-modified syngeneic spleen cells, to affect an ongoing B cell response was studied in vitro. It was found that the expression of NPb idiotype-positive B cells could be selectively inhibited by the addition of antigen-induced suppressor cells in the last 24 h of the in vitro culture. This effector-phase suppression of B cell responses was antigen specific and mediated by an Lyt 1-, Lyt 2+, idiotype-binding, T cell population whose suppressive function was restricted by genes linked to the Igh locus.

Hapten-specific helper T cells III. Fine specificity of the (4-hydroxy-3-nitro-phenyl)acetyl (NP)-specific response in Igh-1b mice

Helper cells, with specificity for the haptens (4-hydroxy-3-nitro-phenyl)acetyl (NP) or (4-hydroxy-5-iodo-3-nitro-phenyl)acetyl (NIP), were raised in B10.BR mice by in vivo priming and in vitro long-term enrichment with hapten-derivatized syngeneic spleen cells. Upon co-culture with the homologous antigen (NP or NIP self), selected helper cells specifically responded by proliferation and by inducing large numbers of B cells to clonal expansion and immunoglobulin secretion. Criss-cross experiments demonstrated the nonheteroclitic nature of antigen recognition by helper cells, as the proliferative and helper cell activities were in every case one order of magnitude higher when confronted with the homologous hapten used for immunization.

Hapten-specific T cell responses to 4-hydroxy-3-nitrophenyl acetyl. VII. Idiotype-specific suppression of plaque-forming cell responses

The ability of suppressor cells induced by the intravenous administration of 4-hydro-3-nitrophenyl acetyl (NP)-modified syngeneic cells to reduce an idiotypic B cell response was studied in both an in vivo and an in vitro system. Idiotype-positive B cells were assayed by the ability of guinea pig anti-idiotypic antiserum to specifically inhibit idiotype-positive plaque formation. It was found that up to 57% of the PFC response in vivo and 100% of the PFC response in vitro was inhibitable with antiidiotypic antiserum. The expression of these idiotype-positive B cells could be suppressed by the transfer of spleen cells form mice treated 7 d previously with NP coupled syngeneic cels. T cells are both required and sufficient for the transfer of idiotype specific suppression. The induction of these idiotype-specific T suppressor cells directly with antigen suggests that recognition of unique determinants on cell surfaces is important for regulation of lymphoid cell interactions. The role of idiotype-specific suppressor cells in the network of lymphoid interactions is discussed.

Preferential production of IgA antibodies by spleen fragments immunized and maintained in vitro

Primary immune responses were induced with a hapten conjugate of Ficol (NIP38-Ficoll) in cultures of mouse spleen fragments. The production of anti-NIP antibodies and mouse immunoglobulins IgA and IgG was monitored by solid-phase radioimmunoassays. Cultures produced IgA and IgG without any stimulation. IgA at a rate of c.60ng/mg of wet tissue per day throughout the 10-day culture period. Background production of IgG gradually declined from almost 1000 ng/mg/day at the beginning to 100 ng/mg/day at the end. Immunization modestly reduced the decline of the IgG production. It increased the production of IgA fourfold between days 6 and 8. It induced an antibody production that had its peak between days 6 and 8. Up to 50 ng of anti-NIP antibody was produced during this period per mg of wet tissue per day. Of this antibody 75-90% was IgA. When the same antigen was injected into mice, more than 75% of anti-NIP antibodies detected in their sera on day 8 were IgG. One cause of the high ratio of IgG/IgA antibodies detected in their sera on day 8 were IgG. One cause of the high rate of IgG/IgA antibodies in vivo is the efficient elimination of oligomeric IgA by the liver. Another possible cause is that the production of IgA is less sensitive than the production of IgG to the adverse conditions of the culture.

Reactivity of hybridoma antibodies with amniotic and plasma fibronectin

Mouse antibodies were prepared to human amniotic fluid fibronectin by means of somatic cell hybrids. Comparison of immunological reactivity of antibodies with amniotic and plasma fibronectin revealed that the two molecules had very similar patterns of antigenic determinants. Antibodies from one cell population, however, bound better to amniotic fluid fibronectin, indicating that there is a difference in the molecular structure of fibronectins isolated from the two sources.

Immunoglobulin diversity in the phylogenetically primitive shark, Heterodontus francisci. Suggested lack of structural variation between light chains isolated from different animals

A two-step procedure employing gel filtration and anion exchange chromatography has been utilized to isolate LMW immunoglobulin from the horned shark, Heterodontus francisci. Light chains obtained by complete reduction and alkylation of the parent protein have been compared by several analytical techniques. Amino acid composition data implies a limited degree of variation in the light chains isolated from individual animals. Polyacrylamide gel electrophoresis of the CNBr digests of the light chains reveal indistinguishable banding profiles of the major peptides. Isoelectric focusing indicates limited heterogeneity in the light chain spectrotype and identity in the pI of the majority of bands detectable by staining. The suggested degree of structural similarity in the light chains of this phylogenetically primitive shark is discussed in terms of the evolutionary position of the species and current theories concerning the origins of structural diversity in immunoglobulins.

Hapten-specific T cell responses to 4-hydroxy-3-nitrophenyl acetyl. III. Interaction of effector suppressor T cells is restricted by H-2 and Igh-V genes

4-Hydroxy-3-nitrophenyl acetyl (NP)-derivatized syngeneic spleen cells administered intravenously induced a population of suppressor T cells that could suppress mice previously primed to NP. The effect was demonstrable when the suppressor cells were transferred to NP-primed mice on the day of challenge for delayed-type hypersensitivity (DTH) responses. In contrast to the suppressor T cell population, which abrogates 5-iodo derivative of NP (NIP)-specific DTH responses when administered before antigen priming, the effector-phase suppressors did not efficiently suppress NIP-specific DTH responses, and were not lysed by treatment with antiidiotype plus complement. Adoptive transfer experiments between major histocompatibility complex and allotype congenic strains of mice allowed demonstration of both Igh-V and I-A restrictions in the transfer of this cell population. The implications of these data in terms of network theories and proposed cellular models for negative immunoregulation were discussed.

Two major idiotypes in mouse anti-(4-hydroxy-3-nitro-phenyl)acetyl (NP) antibodies are controlled by "allelic" genes

Anti-NP [(4-hydroxy-3-nitro-phenyl)acetyl)] antibodies from the primary response of BALB/c mice contain a major idiotype NP-a that is controlled by an allotype-linked gene VHNPa. A new strain distribution pattern for a VH marker was discovered: strains BALB/c, RF, DBA, RIII and SM were positive, and strains C57BL/6, SJL, CBA, A/J, CE, AKR and NZB were negative for the idiotype NP-a. NP-a idiotype chared many characteristics with previously described idiotype NP-b and, therefore, allelism was suggested between them. Both idiotypes have lambda light chains, both seem to be conservative in evolution, both are predominant early in the antibody response. Later during the response, antibodies become increasingly idiotype-negative while at the same time, homogeneous isoelectric focusing patterns become very heterogeneous. The study of VH recombinant strains supported the concept of allelism because in every case studied, the idiotype were mutually exclusive. (C57BL/6 X BALB/c)F1 mice expressed idiotypes NP-a and NP-b regularly and in approximately equal amounts.