Homologous monoclonal antibodies induce idiotope-specific suppression in neonates through maternal influence and in adults exposed during fetal and neonatal life

The fine specificity of idiotype suppression induced early in ontogeny was investigated in the murine A/J anti-azophenylarsonate (Ar) response. Suppression was induced with two hapten-inhibitable, homologous monoclonal anti-idiotopic antibodies, AI and MB, that recognize partially overlapping sets of Ar-immune antibodies. Suppression was found to be idiotope-specific when adult mice were exposed to anti-idiotope as neonates; suppression was also idiotope specific when adult mice were exposed to anti-idiotope during fetal (through maternal inoculation) and neonatal life. Of particular interest, anti-idiotope, administered maternally, induced suppression in offspring first immunized with Ar as neonates, and this suppression was idiotope specific too. Thus, AI and MB induce idiotope-specific suppression in mice exposed to anti-idiotope early in ontogeny. These results parallel previous findings in adult mice and suggest that the mechanism of suppression in very young mice is the same as that in adults.     

Lymphocyte subsets involved in tumor-activated nonspecific feedback suppression

Cells from the spleen, lymph nodes, and peritoneum of DBA/2 mice bearing a subcutaneous tumor mediate nonspecific suppression of an in vitro antibody response to sheep red blood cells (SRBC) when cocultured with a normal T-cell subset(s). The spleen cells from the tumor-bearing mouse required for the suppression bear the Lyt 1 and Ala 1 surface markers characteristic of "inducer" T cells and activated cells, respectively. The activity of this cell population is also sensitive to irradiation. The normal T-cell subset which cooperates in the suppression bears the Qa-1 surface antigen which has been associated with suppressor cell precursors in several systems but lacks detectable surface Lyt 1 and 2 markers. Suppression of antibody responses in spleen cell cultures from tumor-bearing mice alone could also be elicited, but only when increased numbers of cells were cultured. These data are consistent with the theory that a tumor-activated, Lyt 1+ T-cell subset has the capacity to nonspecifically suppress immune responses by activating a Qa-1+ subset(s) of T suppressor cells, perhaps via feedback signals.     

Idiotope antigens (Ab2 alpha and Ab2 beta) can induce in vitro B cell proliferation and antibody production

We previously showed that immunization of various strains of mice with three types of antigen--PC-Hy (nominal antigen), F6-Hy (Ab2 alpha-Hy, and 4C11-Hy (Ab2 beta-Hy)--induces a differential PC-specific, T15-Id+ antibody response. In this report, the in vitro phosphorylcholine (PC)-specific B cell responses induced by these three antigens were studied. A hemocyanin-specific long-term T helper cell line was used to provide help for primary and secondary in vitro T cell-dependent B cell responses. At low doses (0.005 to 0.5 micrograms/ml) of antigen, a significant increase in the proliferation of PC-OVA-primed BALB/c B cells was observed with Ab2-Hy or PC-Hy conjugate, but not unconjugate, antigens. Similar low doses of antigen could stimulate naive B cells to secrete IgM and stimulate PC-OVA- or 4C11-Hy-primed B cells to secret IgM and IgG1 anti-PC antibodies. The percentage of T15-Id of the PC-specific antibodies produced in the in vitro T-B culture was found to be less dominant than that produced by in vivo immunization, suggesting that certain regulatory mechanisms occur in the in vivo environment that may help to maintain the T15-Id dominance. Taken together, our in vivo and in vitro results indicate that idiotope antigens can function like nominal antigens to induce antigen-specific B cell responses. The mechanisms of thymic-dependent B cell activation induced by idiotope and nominal antigen are similar in that the T-B interaction is MHC-restricted and requires cognate recognition.     

Modulation of the murine immune response to streptococcal group A carbohydrate by immunization with monoclonal anti-idiotope

Using monoclonal anti-idiotopes with previously defined specificities for the variable (V) domain of HGAC 39, a monoclonal antibody against streptococcal group A carbohydrate (GAC), we have studied the effect of anti-idiotope on an anticarbohydrate immune response. Anti-IdI-3a and anti-IdI-3b are anti-idiotopes which recognize binding site-associated determinants, whereas anti-IdX recognizes a framework-associated determinant on the HGAC 39 V kappa domain. Each of three anti-idiotopes elicited a specific idiotope response, as measured by inhibition radioimmunoassay, in A/J and C57BL/6J mice. A single immunization with conjugated anti-IdI-3a elicited an idiotope(+), GAC-binding(+) response in C57BL/6J and (BALB/c X CBA/N)F1 male mice, but not in A/J or (CBA/N X BALB/c)F1 male, X-linked immunodeficient mice. When C57BL/6J mice immunized initially with anti-idiotope were further treated with group A vaccine, those receiving anti-IdX had the greatest increase in anti-GAC activity. Stimulation of an anticarbohydrate response with anti-idiotope may therefore be enhanced by selecting anti-idiotopes against both binding site- and framework-associated determinants.     

Immunosuppressive activity of staphylococcal enterotoxin B. II. Activation of suppressor-effector cells by a staphylococcal enterotoxin B-induced suppressor factor

The capacity of staphylococcal enterotoxins to stimulate all T cells bearing certain T cell receptors has recently generated a great deal of interest. These toxins are believed to bind directly both to the TCR:CD4 complex via its V beta domains and to class II MHC molecules on accessory cells prior to T cell activation. Previous studies from this laboratory have demonstrated that staphylococcal enterotoxin B (SEB) is capable of inducing multiple T suppressor cell populations which can inhibit in vitro antibody responses. Additional studies have demonstrated that the suppressive activity of these cells is mediated, at least in part, by an I-J-restricted suppressor factor. Efforts to characterize the inhibitory activity of this factor have demonstrated that the suppressive element is capable of activating both early and late acting suppressor cell populations in vitro. Analysis by both positive and negative selection shows that cells bearing the Lyt1-2+ surface marker phenotype are active early, whereas Lyt1+2+ cells are active both early and late in the antibody response. Additional experiments using various strains of mice as sources of suppressor factor and of naive splenocyte populations have demonstrated that activation of suppressor-effector cells by this suppressor factor is restricted at the I-J, but not Igh, gene locus. These studies suggest that this SEB-induced suppressor factor alone provides the signals necessary for the induction and activation of suppressor-effector cell activity.     

Induction of neutralizing antibody in mice against poliovirus type II with monoclonal anti-idiotypic antibody

Syngeneic monoclonal anti-idiotope antibody Ab2,2-17C3SCC was raised against an idiotope on a protective monoclonal antibody with specificity for poliovirus type II. Ab2,2-17C3SCC detects a paratope-related interspecies IdX. Ab2,2-17C3SCC purified from supernatant fluids of hybridoma cells by protein A-Sepharose was injected into 4- to 6-wk-old BALB/c mice. The sera of the mice were screened for the expression of antibodies bearing the corresponding idiotope. Immunization of mice with Ab2,2-17C3SCC induced antibodies of complementary specificity. Furthermore, micro VN tests suggest that Ab2,2-17C3SCC can substitute for antigen in the induction of anti-polio neutralizing antibodies, and hence can function as a monoclonal anti-idiotypic vaccine.     

Cardiac injury in myocarditis induced by Coxsackievirus group B, type 3 in Balb/c mice is mediated by Lyt 2 + cytolytic lymphocytes

Male Balb/c mice inoculated with a heart-adapted variant of Coxsackievirus, group B, type 3 (CVB3) develop severe myocarditis 7 days later. The lesions are characterized by mononuclear cell inflammation and myocyte necrosis. Infected T-lymphocyte-deficient mice show either minimal or no cardiac injury, although virus concentrations in the hearts of T-cell-deficient and -sufficient animals are similar. Adoptive transfer of 2 X 10(6) CVB3 immune Thy 1+ cells into CVB3-infected T-cell-deficient mice effectively restored myocarditis to levels observed in intact animals. Similar reconstitution with immune Ig+ cells or serum resulted in only a minimal increase in cardiac injury. To determine whether T-lymphocyte-dependent humoral or cellular immunity was responsible for myocarditis. T lymphocytes were obtained from Balb/c mice 6 days after infection with CVB3, separated into Lyt 1+2- (helper) and Lyt 1-2+ (cytolytic/suppressor) cell populations, and 2 X 10(6) of the enriched helper and cytolytic cells were adoptively transfused into infected T-cell-deficient recipients. Animals receiving the immune Lyt2+ cells developed severe myocarditis, had cytolytic T lymphocytes to both CVB3-infected and uninfected myocytes, but lacked a detectable IgG antibody response. Recipients of the Lyt 1+ cells failed to develop either myocarditis or cytolytic T cells but had normal serum IgG antibody titers to the virus. These results demonstrate that cardiac myocarditis is the product of cellular immune mechanisms.     

Role of dextran-specific suppressor T cells in the regulation of the immune response by a reactive form of dextran

Reactive forms of antigens or haptens have been shown to induce a state of hyporesponsiveness mediated in part by suppressor T cells. Injection of Balb/c x C57B16 F1 (CB6F1) mice with a reactive form of dextran B1355S (periodate oxidized dextran, dex-P) specifically reduced responses to dextran immunization within 1 day after dex-P treatment. This unresponsiveness lasted at least 23 days and required a reactive form of dextran for its induction since native dextran and oxidized/reduced dextran failed to induce tolerance. Furthermore, hyporesponsiveness could be induced by iv injection of dextran-coupled cells, especially peripheral blood lymphocytes, a result which suggests that in vivo coupling to cellular antigens is involved in dex-P-induced hyporesponsiveness. Suppression of the anti-dextran response could be transferred to normal mice with T-cell-enriched spleen cell populations from dex-P-injected mice. Interestingly, the presence of B cells in the transferred cell preparations interfered with detection of suppression. Both Lyt 1+2- and Lyt 1-2+ cells were involved in the dex-P-induced suppression; indeed, mixtures of these types of T cells led to the most profound degree of suppression. The suppressive activity of spleen cells from dex-P-injected mice could be removed by passage over dextran-coated plates. Moreover, cells eluted from the plates specifically suppressed anti-dextran responses of normal mice, indicating that dex-P injection induces a population of antigen-binding suppressor cells. This system will allow the study of the suppressor-T-cell receptors in a well-defined idiotypic system.     

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.     

Idiotope vaccine against Streptococcus pneumoniae. A precursor study

An analysis of nominal vs idiotope antigen-induced B cell precursors was performed in A/St mice. With the use of the splenic fragment culture system, the quantity and quality of B cell precursors responding to two anti-idiotope carrier antigens (4C11 hemocyanin and F6 hemocyanin) and nominal antigen (phosphorylcholine-hemocyanin) were compared. In addition, the effect of priming with anti-idiotope-carrier antigens on B cell precursors responding to phosphorylcholine-hemocyanin was determined. We found that one anti-idiotope-carrier antigen, 4C11-hemocyanin, and phosphorylcholine-hemocyanin stimulated similar subpopulations of primary B cells. However, the B cell population stimulated by F6-hemocyanin, the other anti-idiotype complex, was distinct. Furthermore, priming with certain idiotope antigens can direct the phosphorylcholine-hemocyanin response into the expression of idiotypes that may be the most effective in protective immunity. Our results provide essential information for the rational design of idiotype vaccines by clarifying the dynamic relationship of the B cell precursor repertoire with the in vivo antibody response in the response to nominal and idiotope antigens.     

Regulation of anti-hapten antibody response by chemically modified carrier antigen preferentially provoking delayed-type hypersensitivity (DTH). II. DTH-reactivity and carrier-specific suppression of anti-DNP antibody response induced by priming with dodecanoyl-BSA are mediated by functionally distinct T cell subpopulations.

Experiments were carried out to determine whether or not the cell populations involved in DTH and in the suppression of antibody response are identical. The effects of four treatments, i.e., adult thymectomy (ATx), X-irradiation, anti-mouse thymocyte serum (ATS) and hydrocortisone (HC) on the induction of DTH and on the carrier-specific suppression of antibody response were observed in mice immunized with chemically modified antigen, dodecanoyl-BSA (d-BSA), emulsified with complete Freund's adjuvant (CFA), with the following results: 1) DTH induced by immunization with D -BSA remained constant in adult thymectomized mice, whereas the suppression of antibody response was not inducible in these animals. 2) Injection of low doses of ATS caused the depression of DTH in mice primed with D -BSA, but did not affect the suppressive activities of their spleen cells. 3) Sublethal X-irradiation 1 week prior to D -BSA priming inhibited the generation of suppressor cells but did not affect the generation of cells mediating DTH. The suppressive effect was also abrogated by sublethal X-irradiation given 2 days after immunization with DNP-BSA (14 days after priming with D -BSA). 4) The treatment of animals with HC 2 days before the footpad challenge or immunization with DNP-BSA depressed the ability of animals to induce both DTH and the suppression of antibody response. However, the latter was more sensitive to HC than the former. In addition to these results, it was also found that D -BSA-primed spleen cells were capable of suppressing anti-DNP response, but not of inducing DTH-reactivity upon transfer to recipient mice. These results suggest that DTH-reactivity and the carrier-specific suppression of anti-hapten antibody response induced by injection of D -BSA are mediated by different cell populations.     

Idiotype-restricted antibody response to specific immune complexes

In this report, we compared the immunogenicity of specific antigen/antibody complexes with that of free antigen. The complexes were prepared in antigen excess using the TEPC-15 myeloma protein and a phosphorylcholine-containing polysaccharide antigen (PnC), and the PnC-specific antibody response was measured using a hemolytic plaque assay 5 days after immunization. The results showed that the complexes were as immunogenic as the free antigen; however, the PnC-specific antibody response induced with the complexes was completely dominated by one particular idiotope (defined by plaque inhibition with the AB1-2 monoclonal antibody). On the other hand, the response of mice immunized with free antigen (PnC) was dominated to a lesser degree by the AB1-2 idiotope, and there was a great degree of variability in idiotope expression among individual mice. The results suggest that immunization with antigen/antibody complexes restricts the response to the expression of idiotopes that are present in the immune complex.     

Membrane phenotype of murine effector and suppressor T cells involved in delayed hypersensitivity and protective immunity to herpes simplex virus

The membrane phenotype of T cells involved in delayed hypersensitivity (DH), protective immunity, and suppression of delayed hypersensitivity to herpes simplex virus (HSV) has been determined. T cells from immune lymph nodes transferring DH and antiviral immunity to normal recipients were characterized as Lyt 1+2-. There appeared to be no detectable antiviral role for Lyt 1-2+ cells in the transferred cell suspension. Splenic T cells suppressing the induction of DH to HSV were characterized as being both Lyt 1+2- and Lyt 1-2+ 4 weeks after their induction. At earlier times, i.e., after 7 days, the suppression was mediated solely by the Lyt 1+2- population. Thereafter, a progressive increase in the contribution of the Lyt 1-2+ suppressor was observed. Both the early and later phases of suppression were due to I-J positive cells. The nature of the two suppressor cell types is discussed in relation to suppressor cell "cascades" and to the pathogenesis of herpes simplex virus infection.     

Soluble factors in tolerance and contact sensitivity to DNFB in mice. X. IL-2 is the activation signal mediating release of synthesized suppressor factor

Two signals are required for the in vitro activation of Lyt2+ T suppressor cells (Ts) from mice tolerized with 2,4-dinitrobenzene sulfonate (DNBS) to produce soluble suppressor factors (SSF) which suppress the transfer of contact sensitivity to dinitrofluorobenzene (DNFB). Recognition of DNP/class I MHC (signal one) stimulates the Ts to synthesize SSF. Release of SSF requires a soluble mediator (signal two) produced by the interaction of L3T4+ T cells from tolerant mice with I-A on metabolically functional cells in the DNP-presenting cell population. The purpose of this study was to examine the nature of this second Ts activation signal. Coculture of tolerant spleen cells and glutaraldehyde-fixed (Glu-) DNP-labeled spleen cells (DNP-SC) resulted in the synthesis but not release of SSF. Addition of either IL-1 or IL-2 to these cultures induced SSF release. Treatment of such cultured cells with the anti-murine IL-2 receptor antibody PC 61.5.3 blocked the IL-2- and IL-1-stimulated release of SSF. Release of SSF was also blocked when tolerant cells were cultured with (unfixed) DNP-SC in the presence of a monoclonal anti-IL-2 antibody. IL-2 but not IL-1 was able to stimulate the Ts to release synthesized SSF in the absence of L3T4+ TH activity. First, addition of IL-2 to cocultures of tolerant cells and DNP-presenting I-A- cells induced release of the synthesized SSF, whereas addition of IL-1 did not. Second, IL-2 also stimulated SSF release in cocultures of L3T4+ T cell-depleted tolerant cells and Glu-DNP-SC, whereas IL-1 did not. Tolerant cells pretreated with IL-2 and then washed were able to synthesize and release SSF upon culture with Glu-DNP-SC. Pretreatment of tolerant cells with IL-1 did not stimulate SSF release upon subsequent culture with Glu-DNP-SC. These results indicate that the Lyt2+ Ts from DNBS-tolerant mice express IL-2 receptors and IL-2 is the lymphokine which induces the Ts to release synthesized SSF. Thus, IL-2 provides a differentiative signal during the functional activation of these regulatory T cells.     

Antigen- and isotype-specific regulation of IgE responses by Lyt 1+,2,3- and Lyt 1-,2,3+ T suppressor cells

Antigen-specific, IgE isotype-selective suppression is induced following treatment of mice with a high-molecular-weight glutaraldehyde-polymerized ovalbumin preparation (OA-POL). The results show that the suppression is mediated by Lyt 1+,2,3- cells residing in the spleen. Adoptive transfer experiments indicate that Lyt 2,3+ or Lyt 1,2,3+ cells are not required for the establishment of suppression by these Lyt 1+,2,3- suppressor T cells (Ts). Treatment of OA-POL-induced Ts cells with anti-I-Jk serum and complement does not affect their ability to suppress. In marked contrast, spleen cells from animals treated with a single course of OA-POL almost 300 days previously, were shown to contain boosterable memory suppressor T cells (Tsm) which display the Lyt 1-,2,3+ phenotype. The activity of both Ts and Tsm cells appears to result from stimulation by determinants common to native OA and OA-POL rather than by idiotypic determinants expressed on anti-OA antibodies.     

Regulation of an in vitro anti-DNA antibody response by thymocytes and T cells from NZB/W and normal mice

The spontaneous in vitro anti-DNA antibody response generated by preautoimmune and many normal mouse spleen cells was suppressed by the addition of syngeneic thymocytes or splenic T cells. Suppressive activity was found in normal mice (DBA/2J) and to an equivalent degree in the autoimmune (New Zealand Black X New Zealand White)F1 (B/W) strain. The suppressor cells were cortisone-resistant, radiosensitive and carried Lyt 1 and Lyt 2 markers. Nonspecific suppression was not involved since the primary and primed in vitro anti-sheep erythrocyte (anti-SRBC) responses were unaffected. Both spontaneous and lipopolysaccharide-stimulated anti-DNA antibody responses could be suppressed. There was no difference in the suppressive activity of cells from young or old, normal or autoimmune mice. These T cells may therefore play a role in preventing the anti-DNA antibody response in normal and young B/W mice, but evidently fail to influence the development of in vivo anti-DNA autoimmune responses in the old B/W mice.     

Characteristics of 2 types of antigen-binding T suppressors formed during an immune response using T-T hybridomas and their extracts

Antigen-binding T cells of mice immunized with low doses of syngenic spleen cells modified by 2,4,6-trinitrophenyl sulphonic acid, were fused with BW 5147.3.13 thymoma subclone. Suppressor hybridomas were not identical in their differentiating antigens and functional activity. Extract from Lyt 1-2+ hybridoma suppressed efferent and afferent limbs of delayed type hypersensitivity (DTH) in recipients sensitized with subcutaneous injection of 3 X 10(7) TNP-SC. Extract from Lyt 1+2+ I-hybridoma suppressed only afferent DTH limb. It is suggested that during DTH induction with low doses of hapten-modified cells the generation of different types of antigen-binding DTH T suppressors takes place.     

Stimulation of splenic T cells on syngeneic monolayers of epidermal basal cells (EBC) in mice. Regulation by Lyt 1+ and Lyt 2+ cell subsets

Syngeneic proliferative response of splenic T cells against monolayers of epidermal basal cells (EBC) was obtained with C57BL/6 and DBA/2 mice. Optimal response, as assessed by [³H]thymidine uptake, occurred on the 6th day of coculture. The level of [^3H]thymidine uptake by unseparated spleen cells was lower than by fractionated T cells from C57BL/6 mice, and null for DBA/2 mice. It was not significantly different when lymphocytes were cocultured with syngeneic or allogeneic epidermal cells. Ia antigens did not appear to be involved in the syngeneic response, since it was not prevented by pretreating stimulator monolayers with monoclonal anti-Ia^k antibody or by adding this antibody directly to the cultures. When the proliferative responses of separated Lyt 1⁺ and Lyt 2⁺ cell subsets were compared, the prominent role of Lyt 1⁺ cells was demonstrated. Enhancement of the T-cell reactivity by eliminating Lyt 2⁺ cells and suppression of the response of a constant number of Lyt 1⁺ cells by adding Lyt 2⁺ cells suggested that Lyt 2⁺ cells could suppress and modulate the Lyt 1⁺ cell proliferation.     

Idiotype matching: correlation of expression of protective idiotype in sera with survival of tumor mice

A monoclonal anti-Id, 2F10, has previously been shown to protect against transfer of L1210/GZL tumor cells in DBA/2 mice and also to have therapeutic effects in mice with growing tumor. In this study we have measured expression of an idiotope which reacts with a tumor-protective anti-idiotypic antibody, 2F10, in the sera of mice bearing the L1210/GZL tumor. The levels of antibodies binding to 2F10, referred to as the "2F10 idiotope," are different in individual mice and also fluctuate over time. A statistical analysis demonstrated a significant correlation between these changes in 2F10 levels in mice with tumors and their survival times. Increasing 2F10 idiotope in sera of tumor mice correlated with long-term survival, whereas a decreasing trend was found in mice which died shortly after tumor transfer. Correlations between the 2F10 idiotope and survival were observed in groups of mice which had received surgery, cyclophosphamide, a combination of cyclophosphamide and anti-idiotype, or no treatment at all. No correlation between a nonrelated idiotope and survival was noted. Although 2F10 is an idiotope expressed by an anti-tumor-associated Ag antibody, the correlation between anti-tumor-associated Ag titers and survival was significantly lower than that between the 2F10 idiotope and survival. This demonstrates that 2F10 is preferentially associated with antibodies which are involved in tumor regression. Thus, the 2F10 idiotope in sera of tumor-bearing mice has predictive value for survival and tumor regression.     

Tumor-specific idiotype vaccines. II. Analysis of the tumor-related network response induced by the tumor and by internal image antigens (Ab2 beta)

In this study the tumor-specific immuneresponse induced by irradiated tumor cells (L1210/GZL) and by anti-idiotype antibodies was analyzed. The anti-idiotype antibodies (Ab2) were made against the paratope of a monoclonal antitumor antibody (11C1) that recognizes a tumor-associated antigen which cross-reacts with the mouse mammary tumor virus-encoded envelope glycoprotein 52. Two Ab2, 2F10 and 3A4, induced idiotypes expressed by the monoclonal antitumor antibodies 11C1 and 2B2. Cytotoxic T cells, generated by immunization with irradiated tumor cells, lyse 2F10 and 3A4 hybridoma cells. Furthermore, immunization with Ab2 induces tumor-specific cytotoxic T lymphocytes. The frequency of tumor-reactive cytotoxic T lymphocyte was found to be similar in mice immunized with Ab2 or irradiated tumor cells when examined at the precursor level. However, only 2F10 induces protective immunity against the growth of L1210/GZL tumor cells. The depletion of a L3T4+ T cell population from 2F10 immune mice was found to increase the effectiveness of transferred T cells to induce inhibition of tumor growth. The inability of 3A4 to induce antitumor immunity could be correlated with the presence of a population of Lyt2+ regulatory T cells. Collectively, these results demonstrate the existence of a regulatory network controlling the expression of effective tumor immunity. Our results demonstrate that selection of binding site-related Ab2 may not be a sufficient criteria for the development of an idiotype vaccine. A better understanding of the regulatory interactions induced by anti-idiotypes is needed for the design of effective antitumor immunotherapy.