The immune response against anti-idiotope antibodies II. The induction of antibodies bearing the target idiotope (Ab3 beta) depends on the frequency of the corresponding B cells

Disparate adjuvant properties among three formulations of "alum"

Aluminum adjuvants, commonly referred to as "alum," are the most widespread immunostimulants in human vaccines. Although the mechanisms that promote humoral responses to alum-adsorbed antigens are still enigmatic, alum is thought to form antigen depots and induce inflammatory signals that, in turn, promote antibody production. It was recently noted that Imject(®) alum, a commercial aluminum-containing adjuvant commonly used in animal studies, is not the physicochemical equivalent of aluminum adjuvant present in human vaccines. This difference raises concerns about the use of Imject(®) alum in animal research as a model for approved aluminum adjuvants. Here, we compared the capacity of Imject(®) alum, Alhydrogel(®), and a traditional alum-antigen precipitate to induce humoral responses in mice to the hapten-carrier antigen, NP-CGG [(4-hydroxy-3-nitrophenyl)acetyl-chicken γ-globulin]. The magnitude of humoral responses elicited by Alhydrogel(®) and precipitated alum was significantly greater than that induced by Imject(®) alum. The strength of the humoral responses elicited by different alum formulations was correlated with the quantity of pro-inflammatory cytokines induced and the numbers of inflammatory cells at the site of immunization. Moreover, Imject(®) exhibited a severely reduced capacity to adsorb protein antigens compared to Alhydrogel(®) and precipitated alum. These findings reveal substantial differences in the immunostimulatory properties of distinct alum preparations, an important point of consideration for the evaluation of novel adjuvants, the assessment of new alum-based vaccines, and in mechanistic studies of adjuvanticity.

Unreliable measurement of basophil maximum leukotriene release with the Bühlmann CAST 2000 enzyme-linked immunosorbent assay kit

The Bühlmann CAST 2000 enzyme-linked immunosorbent assay is a potentially useful assay for measuring sulfidoleukotrienes released in vitro by allergen-challenged basophils. However, we observed that the positive-control reagent yielded positive signals in cell-free systems. These false-positive results depended on using a mouse anti-FcepsilonRI monoclonal antibody and were prevented by degranulation-inducing reagents other than mouse monoclonal antibodies.

Long-lasting thymus-independent immune responses to anti-idiotype lipopolysaccharide conjugates require continuous B cell renewal

In the present investigation, we have studied the antibody response of both C57BL/6 lipopolysaccharide-responder mice (B6 LPS-R) and C57BL/10ScCr LPS-nonresponder mice (B10.Cr LPS-NR) upon immunization with copolymers of LPS and either Ac38 or Ac46 anti-idiotypes. As both strains of mice studied are of the Ighb allotype the antibody response obtained was quantified by estimating the serum levels of the complementary idiotype, B1-8, in immunized mice. The results show that while the injection of the LPS-R strain B6 with copolymers of LPS anti-idiotype resulted in a long-lasting idiotype response the immunization of the LPS-NR strain, B10.Cr, resulted in virtually no response. This finding allowed us to perform cell transfer experiments to study the response of isolated cells from B6 mice transferred into LPS-NR hosts. Using such a cell transfer model, the results obtained suggest that long-lasting idiotype responses observed in the LPS-R strain require continuous B cell production in bone marrow. The relevance of this finding to the understanding of the long-lasting (fluctuating) antibody responses to nondegradable thymus-independent polysaccharides is discussed.

Murine lupus anti-DNA antibodies cross-react with the hapten (4-hydroxy-5-iodo-3-nitrophenyl)acetyl, but immunization-induced anti-DNA antibodies do not

The antigen-binding selectivity of 2 sets of anti-DNA antibodies from autoimmune mice and from normal mice was examined. Eighteen affinity-purified anti-DNA auto-antibodies from MRL-lpr/lpr mice were examined for binding to the haptens azobenzenearsonate, phosphorylcholine, (4-hydroxy-3-nitrophenyl)acetyl and (4-hydroxy-5-iodo-3-nitrophenyl)acetyl (NIP). Five of these autoantibodies bound to NIP-protein conjugates. In contrast, none of 12 monoclonal antibodies to single-stranded DNA or left-handed Z-DNA induced by immunization of BALB/c and C57BL/6 mice with nucleic acid antigens reacted with the tested haptens. In a reciprocal test of the relationship between anti-DNA and anti-NIP binding, we examined 24 monoclonal antibodies to NIP, from various strains of mice, for binding to DNA. One such antibody from a BALB/c mouse also bound to DNA. These results are discussed in the context of the mechanisms underlying autoantibody hyperproduction.

Cloning of mitogen- and antigen-reactive B lymphocytes on filter paper discs. II. Paratope frequencies within the mitogen-selected repertoire

Paratopic frequencies of C57BL/6 (Igh-Vb) and BALB/c (Igh-Va) mice were compared by determining the frequency of lipopolysaccharide-reactive, splenic B lymphocytes secreting antibody specific for (4-hydroxy-5-iodo-3-nitrophenyl) acetyl (NIP), trinitrophenyl (TNP), phosphorylcholine (PC), NIP/TNP, NIP/PC, and sheep erythrocytes. Despite the known genotypic and phenotypic differences between the two Igh-V loci, no significant differences in paratope frequencies were demonstrated. Similar determinations in C.B-20 mice, Ighb congenics of the BALB/c strain, and in C57BL/10 nude mice indicated that the mitogen-generated paratope frequencies directly reflected the capacity of immunoglobulin variable region elements rather than complex interactive or regulatory controls to generate diversity. We conclude that at least for the paratopic repertoire, the role of the somatic processes for the generation of antibody diversity exceeds the influence of germ-line differences between the Ighb and Igha haplotypes.

The expression of a private idiotope requires pretreatment with noncomplementary anti-idiotypic antibodies

The levan-binding ABPC48 myeloma protein is characterized by 3 idiotopes, (Ids), defined by 3 syngeneic monoclonal anti-idiotypic antibodies (IDA 10, IDA 16 and IDA 17). When BALB/c mice are immunized with levan, they produce anti-levan antibodies, some of which carry the Id 10 and Id 16 but not the Id 17 determinants. In the present study, we attempted to induce the synthesis of Id 17 positive anti-levan molecules. We found that immunization with IDA 17 antibodies alone was ineffective in inducing an Id 17 positive anti-levan response. By contrast, successive immunizations with IDA 10, IDA 16 and IDA 17 antibodies resulted in the synthesis of Id 17 positive anti-levan immunoglobulins. The synthesis of these molecules was concommitant with the induction of Id 10 and Id 16 positive anti-levan antibodies. Thus our data suggest that the Id 17 determinant on anti-levan antibodies is coexpressed with Id 10 and Id 16, and that successive anti-idiotypic treatment may result in the selective expansion of rare ABPC48 cross-reactive idiotype B-cell clone precursors.

A self-Ia reactive T cell clone directly stimulates every hundredth B cell and helps antigen-specific B cell responses

A self-I-A reactive T cell clone has been isolated that proliferates in the presence of irradiated syngeneic spleen cells in mouse serum. The cells directly stimulate approximately every hundredth B cell, which includes small B cells, into both proliferation and antibody formation in the absence of added antigen. There is evidence to suggest that cells of this type are generally present in murine T cell populations. The cells may recognize self-I-A as such. We failed to obtain evidence, but cannot exclude that they recognize an antibody idiotype in addition. The clone also augments antigen-specific antibody responses in vivo and in vitro in the presence of antigen. In the in vitro response to a T-independent TI-2 antigen, the T cells in co-culture with B cells induced specifically the production of IgG1 antibodies, thus mimicking the function of major histocompatibility complex-restricted, antigen-specific helper T cells. However, IgG1 production was not observed when splenic T cells were added to this system. Thus, self-I-A reactive T cells, generally inactive in the system, may locally help B cell responses to antigens which the T cells do not themselves recognize. In such instances one might attribute to the T cells antigen or idiotype-binding specificities which the cells in reality do not display.

Immune response against poly(Glu60,Ala30,Tyr10) (GAT): immunization with monoclonal anti-idiotypic antibodies leads to the predominant stimulation of idiotypically similar immunoglobulins with anti-GAT activity

Two monoclonal anti-idiotypic antibodies (HP-Id20 and HP-Id22) recognizing two different public idiotopes expressed in the anti-poly(Glu60,Ala30,Tyr10) (GAT) response were used to immunize BALB/c and C57BL/6 mice. From these animals hybridomas were isolated. From BALB/c and C57BL/6 mice eight and seven monoclonal antibodies were characterized, respectively. The reagents were classified according to the expression of the public idiotypic specificity p.GAT (recognized by a rabbit antiserum). The anti-GAT activity and the expression of the various idiotopes characterized on anti-GAT polyclonal and monoclonal antibodies were also studied. Most of the reagents are Ab1'-type of antibody resembling anti-GAT antibodies. One anti-anti-idiotypic monoclonal antibody (Ab3) was also isolated from BALB/c mice. This suggests that in this experimental model the repertoire induced after HP-Id immunization and antigen stimulation is comparable. The idiotypic analysis of a large number of anti-GAT and of Ab1' monoclonal antibodies suggests that only two public idiotopes are involved in the anti-GAT response.

A single VH-gene associated with a variety of D- and J-segments encodes for a large family of ABPC48-related antibodies induced by antiidiotypic immunization

Two series of monoclonal antibodies have been obtained from BALB/c mice immunized against two antiABPC48 antiidiotypic antibodies. They are divided into two serologically different classes. Class I antibodies bind only the immunizing antibody; class II antibodies display a broad binding capacity to various antiidiotypic antibodies, and some bind levan, as does ABPC48. Northern blot analyses and partial mRNA sequencing show that all class II antibodies express the VH-gene coding for ABPC48 and UPC10 antilevan antibodies associated with a variety of D- and J-segments. The third hypervariable region of the sequenced antibody with antilevan activity is structurally related to that of ABPC48 and UPC10 antibodies but has a different genetic origin. This study indicates that the identification of idiotype-related antibodies arising from antiidiotypic immunization may be misleading, if based on their antigen-binding properties; and it stresses the importance of structural approaches for the analysis of regulatory mechanisms ruling immune responses.

Immune response induced by a single or several syngeneic monoclonal antiABPC48 antiidiotypic antibodies: no predominant coexpression of ABPC48 idiotopes

BALB/c mice were immunized with monoclonal BALB/c antibodies IDA10, IDA16 and IDA17 raised against the BALB/c ABPC48 myeloma protein. Several procedures of immunization--copolymers with lipopolysaccharide or keyhole limpet hemocyanin, simultaneous or sequential injections of different IDAs--were performed in an attempt to orient the immune response towards the production of ABPC48-like idiotypes. We used a binding assay which identifies two idiotopes on the same molecule to measure the population of antibodies induced in these responses. The expression of ABPC48 cross-reactive idiotypes in immune sera was analyzed. The results show that, with all immunization protocols, immune responses to different monoclonal antiidiotypic antibodies are mostly independent of each other: the coexpression of ABPC48 idiotopes, either private or recurrent on the induced antibodies, is rarely found; it makes it difficult to discriminate by a serological approach between cross-reactive idiotypes and anti-antiidiotypic antibodies. We discuss the interest of combining molecular and serological approaches to identify these two populations of antibodies.

Cellular expression of idiotopes defined by monoclonal antibodies

Monoclonal anti-idiotype (Id) antibodies with specificities for determinants related to the antigen-binding sites of 3 BALB/c myeloma proteins, MOPC-460, HOPC-8 and J558, were used to study Id expression on murine lymphocytes. The monoclonal antibodies were shown to react only with Id structures associated with immunoglobulin on B cells. None of these 3 Id nor a VH Id, detected by a monoclonal antibody made against HOPC-8 heavy chain, were found on T cells. These Id were detected on splenic B cells in neonatal mice; the frequencies in normal, nude and germ-free mice were similar: MOPC-460 Id+: 1.05 +/- 1.7/10(4) spleen cells, HOPC-8 Id+: 1.45 +/- 1.2/10(4) and J558: 0.35 +/- 0.6/10(4). Almost all Id+ cells bore surface IgM, a few expressed surface IgG. MOPC-460 Id+ IgG+ cells were mainly gamma 2a+ or gamma 2b+, whereas J558 and HOPC-8 Id+ IgG+ cells were gamma 3+.

Specificity, duration and mechanism of idiotype suppression induced by neonatal injection of monoclonal anti-idiotope antibodies into mice

Monoclonal antibodies detecting idiotopes on the germ line-encoded anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibody B1-8 were injected at various doses into newborn mice and the expression of B1-8 idiotopes was measured in anti-NP responses in later life. Suppression was long lasting, and a 100-fold increase in the dose of anti-idiotope delayed recovery from suppression by 5-6 weeks. Upon injection of a single anti-idiotope, suppression was observed for all B1-8 idiotopes to various degrees. Certain idiotopically defined antibody phenotypes were much more efficiently suppressed, and later recovered from suppression, than others. This specificity pattern was observed at the level of both B and T cells from the manipulated animals, as demonstrated in cell transfer experiments in which such cells were mixed with normal T and B cells. In these experiments, there was evidence for suppression mediated by regulatory T (and possibly also B) cells. Whereas the B cells from the manipulated animals were idiotypically unresponsive in a T cell-dependent adoptive primary response, the frequency of lipopolysaccharide-reactive B cells expressing the target idiotype was only slightly reduced in these animals as compared to control mice. Together with data on the elimination of anti-idiotope antibody from the neonatally injected animals these results are interpreted in the following way: idiotype suppression is induced through the reaction of anti-idiotope with idiotopes expressed on the surface of newly generated B cells, at microgram concentrations of anti-idiotope. When the concentration of anti-idiotope fall below that level, recovery from suppression sets in. Two types of suppression are induced. The first, namely, direct blockade of B cell maturation, is short-lived. The second involves the induction of regulatory cells, perhaps through idiotope-bearing antibody V regions complexed by anti-idiotope. This type of suppression is long-lived and its specificity depends upon the distribution of the target idiotope in the antibody repertoire and/or peculiarities of the T cell receptor repertoire. It impinges on the selection of the B cell repertoire in the animal as expressed in T cell-dependent (and possibly other) responses and is thus hardly seen at the level of lipopolysaccharide-reactive (immature) cells. Idiotype suppression by regulatory cells may be perpetuated by antigen interacting with idiotypic antibodies on the B cell surface and may therefore play a role in establishing tolerance not only for the expressed antibody repertoire, but for self antigens in general.

Symmetry and asymmetry in idiotypic interactions

At the level of antibody molecules, the partners in an idiotypic interaction are functionally equivalent, and the distinction between "idiotype" and "anti-idiotype" is merely operational. This point must be taken into account in the interpretation of regulatory experiments with "idiotypic" and "antiidiotypic" antibodies. Indeed, consistent interpretations of certain sets of data can be obtained if "idiotype" and "antiidiotype" are used as operational terms for functionally equivalent molecules with complementary binding sites. For interacting antibody populations, symmetrical and asymmetrical situations can occur. The latter case is when an antibody family whose members express a set of idiotypes in various combinations--a typical situation in germ-line encoded immune responses--interacts with a heterogenous population of anti-idiotypes, the common denominators of which are binding sites for the common idiotopes expressed in the idiotypic antibody family. Through this type of interaction, one can explain in a first approximation the experiments of Urbain, Cazenave and others in which antiidiotypic antibody populations (ab2) induce antibodies (ab3) which resemble the original idiotypic population (ab1) idiotypically, but not primarily in antigen-binding specificity. Such a model would also describe an idiotypic network in which germline-encoded recurrent idiotypes (expressed in antibody families of the type described above) interact with anti-idiotypes generated by somatic mutation.