Idiotypic analysis of anti-I-Ak monoclonal antibodies. III. T- and B-cell responses to anti-Ia idiotopes are not modulated by syngeneic anti-idiotypic monoclonal antibodies

To investigate whether anti-idiotypic (anti-Id) antibodies activate T cells either directly or indirectly, we examined the ability of syngeneic anti-Id monoclonal antibodies (mAbs) to regulate idiotype (Id) expression, antigen-binding antibody production, and T-cell reactivity to antigen. Our idiotypic system consists of an anti-I-A mAb that carries an infrequently expressed Id. Using three syngeneic anti-Id mAbs (Ab2), we previously defined the idiotype of the 11-5.2.1.9 (11-5) anti-I-Ak mAb. Two of these mAbs, IIID1 and IA2, recognize the same or closely related epitopes on 11-5 and cross react with two additional anti-I-Ak mAbs, 8B and 39J; the third anti-Id mAb, VC6, recognizes a distinct epitope shared by 11-5 and 8B. In the present study, BALB/c (H-2d) mice were primed with varying doses of these anti-Ids and were then boosted with C3H (H-2k) spleen cells. Among 130 such primed mice, the syngeneic anti-Ids when tested at priming doses between 10 ng and 10 micrograms were unable to induce Id production. The priming anti-Id mAbs persisted in the serum of the mice and were detectable as late as 40 days after priming. Ab1 expression was not modulated in BALB/c mice immunized with KLH-coupled Ab2, however, this immunization elicited the production of Ab3 which shared idiotypes with 11-5, 8B, and 39J. BALB/c anti-C3H alloreactive T-cell clones were also not induced by anti-Id priming, nor could they be shown to bind directly to the three Ab2 used. Nevertheless, the proliferative response of one anti-I-Ak specific T-cell clone that recognizes the same epitope as 11-5, 8B, and 39J, was inhibited by the IIID1 and IA2 Ab2. Thus, a T cell can express an idiotype shared by a B cell, but the linked recognition of an Id-associated carrier determinant(s) by an alloreactive T cell is required to elicit an anti-Id antibody response. These results favor the possibility that the activation of T cells is not dependent upon their ability to bind to anti-Id, but rather on their capacity to respond to epitopes of Id-anti-Id antigen-antibody complexes formed on B cells.     

Anti-idiotype-induced, lipopolysaccharide-specific antibody response to Pseudomonas aeruginosa

Antibody directed to the O-specific polysaccharide (Ps) side chain of Pseudomonas aeruginosa LPS provides immunotype-specific protection against infection by virtue of enhancing opsonophagocytosis. We have developed a syngeneic anti-idiotypic antibody (mAb2) directed to a functionally active monoclonal immunotype 1 Ps-antibody (mAb1). The mAb2 performed as a molecular mimic of Ps as evidenced by 1) blocking of mAb1/mAb2 interaction by Ps, 2) blocking of mAb1/Ps binding by mAb2, 3) cross-species binding of mAb2 to human Ps antibodies from individuals immunized with the same immunotype 1 Ps, and 4) induction of anti-LPS antibody by immunization with mAb2 in syngeneic mice. Our studies thus show that an anti-idiotypic antibody may functionally mimic the O-polysaccharide of P. aeruginosa LPS, and bind to cross-reactive Id present in human Ps antibodies. We have further shown that this anti-idiotypic antibody induces anti-LPS antibody when used as an Ag in syngeneic mice, suggesting that this approach may eventually be used to successfully immunize humans.     

Analyses of Idiotypes on Anti-α-1, 6-Dextran Antibodies in Mice

When mice of strains C57BL/6, C3H/He, and BALB/c were immunized with native dextran B512, only a small amount of IgM antibody was produced, but a substantial amount of anti-dextran antibody of IgG class was produced after immunization with a conjugate of dextran T10 and keyhole limpet hemocyanin regardless of the mouse strain used. Isoelectric focusing (IEF) spectra revealed limited heterogeneity of anti-dextran antibody of IgG class with strict consistency in all individual sera from C57BL/6 mice, even after secondary immunization, whereas antibodies from C3H/He and BALB/c mice showed more heterogeneous IEF spectra with some individual variations. Rabbit anti-idiotypic (Id) antibodies were raised by immunization with a subfraction of anti-dextran antibody of IgG class from C57BL/6 mice, which showed major bands focused at around pH 7.7 upon IEF. It was found by using the anti-Id antibodies that virtually all anti-dextran antibody molecules of both IgG and IgM classes from C57BL/6 mice possessed common Id determinants which can be classified into two specificities, one specific for antibody from C57BL/6 mice and the other cross-reactive with antibodies from BALB/c and C3H/He mice. About 80% of the antibody molecules from BALB/c and less than 20% of those from C3H/He mice were positive for the interstrain cross-reactive Id. Both Id determinants seemed to be closely related to the antigen binding sites, or at least to reside in the vicinity of the antigen binding sites of anti-dextran antibody.     

Induction of an immune response through the idiotypic network with monoclonal anti-idiotype antibodies in the carcinoembryonic antigen system.

Anti-idiotype antibodies can mimic the conformational epitopes of the original antigen and act as antigen substitutes for vaccination and/or serological purposes. To investigate this possibility concerning the tumor marker carcinoembryonic antigen (CEA), BALB/c mice were immunized with the previously described anti-CEA monoclonal antibody (MAb) 5.D11 (AB1). After cell fusion, 15 stable cloned cell lines secreting anti-Ids (AB2) were obtained. Selected MAbs gave various degrees of inhibition (up to 100%) of the binding of 125I-labeled CEA to MAb 5.D11. Absence of reactivity of anti-Id MAbs with normal mouse IgG was first demonstrated by the fact that anti-Id MAbs were not absorbed by passage through a mouse IgG column, and second because they bound specifically to non-reduced MAb 5.D11 on Western blots. Anti-5.D11 MAbs did not inhibit binding to CEA of MAb 10.B9, another anti-CEA antibody obtained in the same fusion as 5.D11, or that of several anti-CEA MAbs reported in an international workshop, with the exception of two other anti-CEA MAbs, both directed against the GOLD IV epitope. When applied to an Id-anti-Id competitive radioimmunoassay, a sensitivity of 2 ng/ml of CEA was obtained, which is sufficient for monitoring circulating CEA in carcinoma patients. To verify that the anti-Id MAbs have the potential to be used as CEA vaccines, syngeneic BALB/c mice were immunized with these MAbs (AB2). Sera from immunized mice were demonstrated to contain AB3 antibodies recognizing the original antigen, CEA, both in enzyme immunoassay and by immunoperoxidase staining of human colon carcinoma. These results open the perspective of vaccination against colorectal carcinoma through the use of anti-idiotype antibodies as antigen substitutes.     

The effects of handling on antibody production, mitogen responses, spleen cell number, and lymphocyte subpopulations

The effects of a simple psychosocial manipulation, handling, on immune function in BALB/c.ByJ mice were studied. Handling for two minutes/day prior to immunization was shown to be associated with a decreased primary IgG antibody response to the protein antigen keyhole limpet hemocyanin. Handling was also associated with decreased T cell proliferative responses to Concanavalin A. No reliable changes in spleen cell number or lymphocyte subsets were found. These findings demonstrate that simply picking up an animal results in modulation of the immune response. These data are also of interest for their obvious methodological implications.     

Thymus-dependent antiidiotype and anti-antiidiotype responses to a dinitrophenyl-specific monoclonal antibody

BALB/c mice were inoculated i.p. with graded doses of a DNP-specific, IgM mAb (designated 57.1). Injection with unmodified 57.1 in the absence of adjuvants resulted in the generation of an anti-Id response (Ab2) and an anti-anti-Id response (Ab3). The generation of serum anti-Id antibodies was found to be thymus dependent. Nude mice immunized with 57.1 were unable to produce a serum Ab2 response above nonimmunized controls whereas euthymic mice receiving identical doses of 57.1 produced strong Ab2 responses. To examine the specificity of serum anti-Id, sera from mice receiving 57.1 were screened against a panel of mAb representing at least five distinct VH gene families. Serum titers were significantly higher against 57.1 than against any of the other antibodies in the panel. Three of the antibodies in this panel bind FD5-1, a monoclonal anti-Id (Ab2) that also binds 57.1. However, sera from mice receiving 57.1 bound 57.1 only. Thus, the serum Ab2 response appears to be highly specific for idiotopes on 57.1. The predominant isotype of these anti-Id antibodies was IgG1. The number of isotypes detected increased in a dose dependent manner with all IgG subclasses having anti-Id specificity in sera from animals receiving the higher doses of 57.1. Further analysis of the serum demonstrated that approximately 8% of the Ab2 response was paratope-specific (inhibitable by the monovalent hapten DNP-lysine). The same sera were analyzed for the presence of Ab3 by binding to the monoclonal anti-Id antibody FD5-1. Lower serum titers of Ab3 were generated in comparison to serum titers of Ab2. Analysis of the binding specificity of the Ab3 response revealed that DNP-BSA was able to partially inhibit the binding of serum IgM and IgG Ab3 to FD5-1. A subset of the Ab3 response. Ab1' that is specific for DNP was observed in a direct binding assay where detectable amounts of DNP binding IgM, IgG1, and IgG3 isotypes were present. We have thus described a complete circuit (Ab1----Ab2----Ab3) of antibodies within the Id network by immunizing animals with an unmodified mAb in the absence of Ag or adjuvants.     

Immunogenicity and biophysical properties of a Nocardia brasiliensis protease involved in pathogenesis of mycetoma

We isolated and purified to homogeneity a caseinolytic protease from a Nocardia brasiliensis cell extract. Preparative polyacrylamide gel electrophoresis and electroelution were employed for purification. This purified protease was injected in BALB/c mice and induced IgM and IgG anti-protease antibodies. Active immunization of mice with this protease prevented mycetoma development in experimentally infected animals. Passive immunization with hyperimmune sera containing a high anti-protease antibody titer conferred partial but transient protection when collected 30 days after donor's immunization. The protective effect of hyperimmune sera was lost when obtained from donors after 60 days from their immunization despite its higher anti-protease antibody concentration. Cytokines are good candidates to explain these findings.     

Bispecific anti-idiotype/anti-CD3 antibody therapy of murine B cell lymphoma.

Retargeting of T cells by bispecific IgG which binds to both CD3 and a tumor-associated Ag can induce T cell lysis of target cells irrespective of TCR specificity. The current studies were designed to further explore the efficacy and specificity of bispecific IgG-directed therapy in an immunocompetent animal model, and to evaluate the mechanisms responsible for bispecific IgG-directed inhibition of tumor cell growth by using the 38C13 murine lymphoma system. In vitro, proliferation of activated T cells in the presence of bispecific IgG was increased when the relevant, but not the irrelevant target cells were present. Bispecific IgG specifically induced activated T cell mediated lysis of cells expressing the target Ag, but not of cells expressing an irrelevant Ag, even when the irrelevant cells were in the same cell mixture, indicating contact between target cells and T cells plays a major role in bispecific IgG-mediated lysis. Bispecific IgG was less effective than anti-Id at inducing target cell lysis when peritoneal macrophages were used as effectors, suggesting bispecific IgG Fc is not responsible for cytotoxicity in this system. In vivo, bispecific IgG was significantly superior to anti-Id, anti-CD3, or a combination of anti-Id and anti-CD3 in preventing tumor growth in immunocompetent mice inoculated with syngeneic lymphoma. Phenotypic evaluation of tumors that emerged despite therapy indicated bispecific IgG selects for the emergence of Id variant lymphoma cells. In separate studies, 38C13 tumor inocula containing cells recognized by the therapeutic antibody were supplemented with a small number of 38C13 cells which expressed a distinct Id not recognized by the therapeutic antibody. Untreated mice inoculated with this mixture developed tumors containing cells of both phenotypes, whereas tumors emerging from mice treated with bispecific IgG contained only cells expressing the nonreactive Id. These studies demonstrate bispecific IgG-directed lysis is therapeutically superior to monospecific anti-Id therapy in the 38C13 tumor model, and that tumor lysis is mediated largely by cell-cell contact. As with other forms of anti-Id based therapy, Id variants can emerge as resistant cell populations after bispecific IgG therapy.     

Monoclonal anti-idiotype induces protection against the cytotoxicity of the trichothecene mycotoxin T-2

An IgG1 mAb, designated HD11, specific for the trichothecene mycotoxin T-2 and capable of neutralizing its cytotoxicity was used to generate a syngeneic monoclonal anti-Id antibody. The generated anti-Id mAb, designated DE8, specifically bound to HD11 anti-T-2 mAb, and not to IgG1 mAb of irrelevant specificity or to normal mouse Ig. DE8 inhibited the binding of HD11 anti-T-2 to T-2-BSA-coated plates, whereas a control anti-Id mAb did not, suggesting recognition of an Id determinant associated with the T-2 binding site of HD11. Moreover, the binding of HD11 to DE8 and that of DE8 to HD11 were specifically inhibited by free T-2 mycotoxin. DE8 mAb was efficient in abrogating the protective effect of HD11 in the cytotoxicity of T-2 on the human epidermoid carcinoma cell line Hep-2. In vivo immunization of BALB/c mice with DE8 conjugated to KLH induced an anti-T-2 antibody titer comparable to that obtained with T-2-OVA immunization, whereas immunization with unconjugated DE8 resulted in a lower titered anti-T-2 response. Immunization with DE8-keyhole limpet or with unconjugated DE8 induced anti-T-2 antibody responses characterized by expression of "HD11-like" Id and by protection against T-2 cytotoxicity. However, the T-2-OVA-induced anti-T-2 response lacked the HD11+ Id and was only partially protective against T-2 cytotoxicity. This represents the first demonstration of the use of an anti-Id based vaccine in the in vivo induction of a protective antibody response against the cytotoxicity of a nonproteinaceous, small m.w. biologic toxin, whose very toxic nature precludes its use as the immunogen.     

Biological Mimicry of the Bluetongue Virus Core Protein VP7 by Rabbit Anti-Idiotype

A subpopulation of rabbit polyclonal anti-idiotypic antibody (anti-Id) was previously produced to a murine monoclonal antibody (mAb) (M1875) specific for the bluetongue virus core protein VP7. In this report, mimicry of VP7 by this anti-Id (designated RAb2-A) was functionally analyzed through immunization of Balb/c mice with RAb2-A or purified VP7. Animals immunized with RAb2-A were able to produce an M1875-like Ab3 antibody response with idiotype and epitope specificity resembling that of M1875 without subsequent exposure to the nominal antigen. This conclusion was supported by experiments showing that the RAb2-A-induced Ab3 antibodies (i) reacted specifically with the immunizing anti-Id; (ii) were capable of binding VP7; (iii) inhibited M1875 from binding to VP7; and (iv) inhibited M1875 from binding to RAb2-A. Similarly, mice immunized with purified VP7 also produced antibodies that exhibited characteristics such as idiotype and epitope specificity in common with M1875. No antibody response to VP7 was detected in control groups of mice immunized with either normal rabbit IgG or BHK-21 cell components. Therefore, it can be concluded that rabbit anti-Id RAb2-A mimics an M1875-defined VP7 epitope sufficiently to function as a surrogate antigen for inducing an anti-bluetongue virus response.     

Monoclonal anti-idiotypic antibodies induce humoral immune responses specific for simian virus 40 large tumor antigen in mice.

Mouse monoclonal anti-Id antibodies were generated against a mouse mAb (Ab-1) preparation specific for SV40 large tumor Ag (T-Ag). Four monoclonal anti-Id preparations each inhibited the binding of the monoclonal anti-SV40 T-Ag Ab-1 preparation to SV40 T-Ag. These anti-Id preparations appeared to recognize similar idiotopes on the monoclonal anti-SV40 T-Ag Ab-1 based on competitive cross-inhibition studies. One of these anti-Id preparations, designated 57B, was examined further for its in vivo modulatory capacity in mice. This anti-Id induced an Ab-3 response in BALB/c mice that recognized SV40 T-Ag (Ag+) and expressed an Id that was shared by the monoclonal anti-SV40 T-Ag Ab-1 preparation (Id+). The Id expressed on the Ab-3 differed from the Id induced in BALB/c mice immunized with the nominal SV40 T-Ag. Furthermore, characterization of the humoral immune response induced by anti-Id immunization indicated that the Ab-3 also recognized different epitopes on SV40 T-Ag when compared to the anti-SV40 T-Ag Ab-1 preparation used to generate the anti-Id. These studies indicate that monoclonal anti-Id can be used to induce humoral immune responses to a viral encoded tumor-associated Ag in vivo with 1) and Id specificity that differs from that expressed on antibodies produced by immunization with the nominal Ag and 2) an epitope specificity distinct from the Ab-1 preparation used for the production of the anti-Id.     

Anti-immunoglobulin antibodies. II. Expression of individual and cross-reactive idiotypes on syngeneic and homologous anti-idiotype antibodies

Syngeneic anti-(anti-Id) antibodies were prepared against BALB/c anti-A48Id antibodies, BALB/c anti-460Id monoclonal antibodies, and A/J anti-J558 IdI monoclonal antibodies. With these anti-(anti-Id) antibodies we identified cross-reactive idiotypes on syngeneic and homologous anti-A48Id and anti-460Id antibodies. By contrast, tbe idiotypic determinants of A/J anti-J558 IdI monoclonal antibodies were not shared by other syngeneic, homologous, or xenogenic anti-J558 IdI or IdX antibodies. These results suggest that idiotype-antiidiotype reactions that serve as regulatory controls within the immune system are characteristic for each particular antigen system, strain, or species and that such interactions make the system self-limited with respect to the whole antild repertoire.     

Carrier-induced tolerance to nucleic acid antigens.

BALB/c and SJL mice were treated with nucleosides-IgG1 as a tolerogen, before either primary or secondary immunization with nucleosides-keyhole limpet hemocyanin. Nucleoside-specific responses were measured serologically by a modified Farr assay, with either 14C-labeled denatured DNA or nucleosides-131-I-labeled BSA as test antigen. Specificity of the response was tested by hapten inhition experiments. Multiple doses of nucleosides-IgG1 tolerogen given before the primary or secondary immunization effectively suppressed the secondary and tertiary anti-nucleoside responses. The tolerogen did not suppress the response to an unrelated hapten-KLH conjugate. The IgG alone did not suppress the anti-nucleoside response of BALB/c mice to nucleosides-KLH. Single doses of tolerogen before the primary or secondary immunization were less effective. Residual antibody in partially suppressed BALB/c mice showed changes in specificity as compared to controls. Suppression of the secondary response of SJL mice was measured much more readily by binding of nucleosides-131-I-BSA than by binding of denatured DNA. This reflected an altered specificity of the residual antibody; in control animals, antibodies were directed against all four nucleosides, whereas the antibodies of partially suppressed animals were directed only against guanosine. Suppression of anti-nucleic acid antibody responses may have therapeutic application in the management of systemic lupus erythematosus.     

Murine immune response to the Neisseria meningitidis group C capsular polysaccharide. I. Ontogeny

The immune response to polysaccharide Ag develops late in ontogeny and the underlying mechanisms of the infant unresponsiveness are poorly understood. The development of vaccines that will prove efficacious in infants has been hindered by the lack of animal systems suitable for studying immunity to human pathogens. We have examined the BALB/c murine response to the capsular polysaccharide of Neisseria meningitidis group C (MCPS), a homopolymer of alpha(2----9) sialic acid, as a model system for the development of immunity to bacterial polysaccharides in man. We have observed the appearance of natural antibody of both IgM and IgG classes which increases with age, and the transfer of maternal IgG to the offspring. Both the naturally occurring and postimmunization serum responses are restricted to the IgM and IgG3 isotypes, and include antibody titers to both MCPS as well as a natural O-acetyl-negative variant (OAc-). The preimmune anti-OAc- antibodies, in contrast to anti-MCPS, were restricted to the IgM class, whereas after immunization with MCPS both IgM and low titers of IgG3 antibodies to OAc- were produced. These studies demonstrate that the BALB/c mouse strain shows a markedly similar immune profile to that observed in man.     

Idiotype vaccines against human T cell acute lymphoblastic leukemia. I. Generation and characterization of biologically active monoclonal anti-idiotopes

A murine monoclonal anti-tumor antibody termed SN2 (Ab1), isotype IgG1-kappa, that defines a unique human T cell leukemia-associated cell-surface glycoprotein, gp37 (m.w. 37,000), was used to generate monoclonal anti-idiotype antibodies (Ab2) in syngeneic BALB/c mice. The Ab2 were screened on the basis of their binding to the F(ab')2 fragments of SN2 and not to the F(ab')2 of pooled normal BALB/c mice sera IgG1 or to an unrelated BALB/c monoclonal antibody of the same isotype. Fifteen Ab2, obtained from two fusions, were specific for the SN2 idiotope and not against isotype or allotype determinants. To find out whether these Ab2 are directed against the paratope of SN2, the binding of radiolabeled SN2 to leukemic MOLT-4 and JM cells which contain gp37 as a surface constituent was studied in the presence of these anti-idiotopes. Clone 4EA2 inhibited the binding 100% at a concentration of 50 ng and 4DC6 inhibited 90% at a concentration of 250 ng. A third clone 4DD6 gave about 50% inhibition. Similar was the inhibition of SN2 binding to insolubilized MOLT-4 antigen or cell membrane preparation. The binding of SN2 (Ab1) to 4EA2 and 4DC6 was also inhibited by semipurified preparation of gp37 antigen. These results demonstrate that at least two of the anti-idiotope antibodies are binding either at or near the binding site idiotope of SN2. Next, the purified Ab2 was used to immunize syngeneic mice to induce antibody binding to MOLT-4 cells or gp37. Sera from mice immunized with 4EA2 and 4DC6 coupled to keyhole limpet hemocyanin contained antibodies which bind to semipurified gp37 antigen and MOLT-4 cells. Immune sera inhibited the binding of iodinated Ab2 and Ab1 indicating that an anti-anti-idiotopic antibody (Ab3) in mice shares idiotopes with Ab1 (SN2). Also, the binding of iodinated Ab2 to Ab1 was inhibited by rabbit antisera specific for gp37. Collectively, these data suggest that anti-idiotype antibodies 4EA2 and 4DC6 may be useful in the generation of idiotype vaccines against human T cell leukemia.     

Induction of antibodies against Newcastle disease virus with syngeneic anti-idiotype antibodies in mice

Anti-idiotype antibodies were induced by injecting BALB/c mice with syngeneic antibody against the hemagglutinin of Newcastle disease virus (NDV). These anti-idiotype antibodies were purified and injected into syngeneic mice. Anti-anti-idiotype sera thus prepared contained antibodies against the hemagglutinin of NDV. This NDV-mouse experimental system might provide a good experimental model for investigation of basic problems of idiotype vaccine.     

High efficiency cross-reactive monoclonal antibody production by oral immunization with recombinant norwalk virus-like particles

Monoclonal antibodies (MAbs) are important for in-depth antigenic characterization and diagnosis of infections with human caliciviruses that cause almost all outbreaks of nonbacterial gastroenteritis. We compared different routes of immunization with nonreplicating virus-like particles (VLPs) from recombinant Norwalk virus (rNV) and recombinant Mexico virus (rMX) administered to BALB/c mice to determine the efficiency of hybridoma production. Oral immunization with VLPs without adjuvant resulted in high yields of MAb-secreting hybridomas (90%) to these VLPs of IgG (61%), IgM (29%) and IgA (10%) isotypes. Fusions with mesenteric lymph node lymphocytes yielded MAbs of various subclasses including IgG2a, IgG3, IgM and IgA. These results suggest that an immunization route that mimics the natural route of viral infection pathway may facilitate MAb technology by increasing the yields of antibody secreting hybridoma cells.     

In vitro T cell-mediated killing of Pseudomonas aeruginosa. V. Generation of bactericidal T cells in nonresponder mice

We have previously reported that BALB/c mice immunized with 10 micrograms of a Pseudomonas aeruginosa polysaccharide antigen (PS) and 100 micrograms vinblastine sulfate develop T cell-mediated protective immunity, but fail to generate an antibody response. Vinblastine functions in this system to remove a suppressor cell that normally inhibits expression of this form of immunity after PS immunization. T cells from CB.20 mice immunized with the 10 micrograms of PS and 100 micrograms vinblastine fail to kill P. aeruginosa in vitro. These mice are allotype congenic with BALB/c mice, differing at loci closely linked to the IgH-1 locus. Immunization of CB.20 mice with 10 micrograms PS and 100 micrograms vinblastine results in the appearance of T cells which suppress in vitro bactericidal activity of BALB/c T cells. In the current study we found that T cell-mediated bactericidal activity can be generated in CB.20 mice by increasing the dose of vinblastine given at the time of PS immunization. The phenotype of the CB.20 bactericidal T cell generated by high dose vinblastine is identical to that of the BALB/c bactericidal T cell, and the CB.20 bactericidal T cell can adoptively transfer protective immunity to granulocytopenic mice. After immunization of BALB/c and CB.20 mice with PS alone, approximately one log fewer CB.20 T cells than BALB/c T cells are required to suppress bacterial killing in vitro. Furthermore, the number of CB.20 T cells required to suppress in vitro bacterial killing is directly correlated with the dose of vinblastine administered at the time of immunization. Increasing the immunizing dose of PS overcomes suppressor activity and allows the generation of bactericidal T cells in BALB/c mice without a requirement for vinblastine. CB.20 mice fail to generate bactericidal T cells after immunization with high doses of PS. These results indicate that CB.20 and BALB/c mice both possess the full repertoire of T cells required to express bactericidal T cell activity and that the differences in their responses reflect only quantitative differences in suppressor cell activity.     

In vitro T cell-mediated killing of Pseudomonas aeruginosa. IV. Nonresponsiveness in polysaccharide-immunized BALB/c mice is attributable to vinblastine-sensitive suppressor T cells

We reported previously that BALB/c mice immunized with a polysaccharide (PS) antigen isolated from immunotype 1 Pseudomonas aeruginosa and vinblastine sulfate develop T cell-mediated protective immunity, despite their failure to produce specific antibody. In vitro, Lyt-1-,2+, I-J+ T cells from vinblastine- and PS-immunized mice kill P. aeruginosa by secretion of a bactericidal lymphokine. BALB/c mice immunized with PS alone generate neither protective antibodies nor a protective T cell response. The current studies indicate that T cells from mice immunized with PS alone significantly suppress the bactericidal activity of T cells from mice immunized with vinblastine and PS. The suppressor T cells are of the same Lyt-1-,2+, I-J+ phenotype as the bactericidal T cells. Suppression is mediated by a soluble product of these suppressor T cells which both inhibits T cell proliferation and interferes with the production or release of the bactericidal lymphokine. Cyclophosphamide, used in other systems to remove suppressor T cells, fails to enhance bacterial killing and does not inhibit suppressor cell activity. These studies indicate that immunization with PS elicits responses in two functionally distinct subgroups of Lyt-1-,2+, I-J+ T cells, and that these cells are distinguishable by their sensitivity to vinblastine sulfate.     

Immune response to phosphorylcholine. I.V. Comparison of homologous and isologous anti-idiotypic antibody.

Homologous and isologous anti-idiotypic antibodies against the PC-binding BALB/c myeloma protein HOPC-8 were raised in A/He and BALB/c mice, respectively. Isologous and homologous anti-HOPC-8 serum suppressed the response to PC in vitro specifically. The antibodies were purified by using HOPC-8 immunoabsorbent. Purified isologous and homologous anti-idiotypic antibody were labeled with 125I and compared for Ig class composition and idiotype-binding specificity. Both kinds of anti-idiotypic antibodies were predominantly IgG1, were highly specific for the HOPC-8 idiotype, and had a smiliar affinities for the PC-binding site. These findings demonstrate that anti-HOPC-8 antibodies raised in A/He and BALB/c mice are very similar in their biologic and immunochemical poperties.