Assessing immune competence in pigs by immunization with tetanus toxoid

Immune competence can be tested by challenging organisms with a set of infectious agents. However, disease control requirements impose restrictions on the infliction of infections upon domestic pigs. Alternatively, vaccinations induce detectable immune responses that reflect immune competence. Here, we tested this approach with tetanus toxoid (TT) in young domestic pigs. To optimize the vaccination protocol, we immunized the pigs with a commercial TT vaccine at the age of 21 or 35 days. Booster immunizations were performed either 14 or 21 days later. TT-specific antibodies in plasma as well as lymphoproliferative responses were determined both 7 and 14 days after booster immunization using ELISA and lymphocyte transformation tests, respectively. In addition, general IgG and IgM plasma concentrations and mitogen-induced proliferation were measured. The highest TT-specific antibody responses were detected when blood samples were collected 1 week after a booster immunization conducted 21 days after primary immunization. The pigs’ age at primary immunization did not have a significant influence on TT-specific antibody responses. Similarly, the TT-specific proliferative responses were highest when blood samples were collected 1 week after booster immunization, while age and time of primary and booster immunization were irrelevant in our setup. While general IgG and IgM plasma levels were highly age dependent, there were no significant age effects for TT-specific immune responses. In addition, mitogen-induced proliferation was independent of immunization as well as blood sampling protocols. In summary, our model of TT vaccination provides an interesting approach for the assessment of immune competence in young pigs. The detected vaccination effects were not biased by age, even though our data were acquired from immune systems that were under development during our tests.     

Mucosal and systemic immune responses of mice to tetanus toxoid coadministered nasally with AFCo1

Mucosal immune responses are an early and important line of defense against pathogens. The current understanding of the mucosal immune system allows us to consider the use of nasal immunization for induction of antigen-specific immune responses at the mucosal surface and the systemic compartment. Mucosal adjuvants are key for developing novel mucosal vaccines and represent 1 approach to improving mucosal and systemic immunity. However, few mucosal vaccine adjuvants are currently approved for human use. Neisseria meningitidis B proteoliposome-derived cochleate (AFCo1 - Adjuvant Finlay Cochleate 1) has been demonstrated to be a potent mucosal adjuvant. The present work demonstrates that intranasal immunization of 3 doses of tetanus toxoid (TT) coadministered with AFCo1 in mice promotes high systemic and mucosal responses. The anti-TT IgG serum titers and the mucosal anti-TT IgA in saliva and vaginal wash were significantly higher than TT alone. The analysis of antibody subclasses showed that intranasal administration of AFCo1 + TT induced not only IgG1 but also IgG2a anti-TT antibodies at levels comparable to those obtained with TT vaccine (vax-TET). These data support the fact that AFCo1 is a potent mucosal adjuvant in nasal immunization to a coadministered protein antigen.     

C群奈瑟氏脑膜炎球菌荚膜多糖-TT结合疫苗的制备及其在小鼠体内免疫原性的研究

将C群脑膜炎球菌荚膜多糖以ADH作为间隔剂与TT结合形成GCMP-TT结合疫苗,然后用此结合疫苗免疫NIH小鼠,结果显示使用GCMP免疫小鼠后仅能产生较低水平抗GCMP的IgG抗体,而用GCMP-TT免疫后小鼠血清中产生了较GCMP免疫显著增高抗GCMP的IgG抗体,并且GCMP-TT组第二次和第三次免疫后与初次免疫相比,IgG抗体水平均有显著升高(P<0.01),表明GCMP-TT结合疫苗具有免疫记忆和再次免疫加强应答效应。补体介导的血清抗体体外杀菌试验结果证明,GCMP-TT结合疫苗组免疫小鼠诱导的抗体IgG比GCMP组具有增强的体外杀菌活性。     

The induction and suppression of in vitro IgG anti-tetanus toxoid antibody synthesis by human lymphocytes stimulated with tetanus toxoid in the absence of in vivo booster immunizations

This report presents a new approach that by-passes booster immunizations with tetanus toxoid (TT) before in vitro studies of antibody (Ab) production. The methodology for optimal TT-induced synthesis of specific IgG anti-tetanus toxoid Ab (IgG anti-TT) by peripheral blood mononuclear cells (PBMC) from randomly selected TT immune individuals without recent booster immunizations is described. PBMC from most normal immune subjects could be repeatedly induced to produce in vitro IgG anti-TT; PBMC from subjects with high TT titers are not required for this new approach. This approach uses high cell concentrations in multiple replicate microcultures and TT washout to obtain optimal IgG anti-TT synthesis. Washed cultures produced more Ab than nonwashed cultures (p less than or equal to 0.005). The readdition of TT (2.5 to 250 ng/ml) to the culture media after washout of TT on day 4 suppressed specific Ab formation, whereas diphtheria toxoid added at comparable doses did not inhibit specific Ab formation. Suppression of antibody synthesis mediated by T cells could be induced by TT per se, and was not due to binding of synthesized Ab to TT in the latter 8 days of culture. In addition, suppression could not be induced in the first 4 days of culture by IgG anti-TT, IgG, or IgM. This approach permits the analysis of antigen-specific regulatory circuits in the steady and activated immune states, and the evaluation of in vivo and in vitro effects of biologic response modifiers on specific Ab production.     

Analysis of the antigen- and mitogen-induced differentiation of B lymphocytes from asymptomatic human immunodeficiency virus-seropositive male homosexuals. Discrepancy between T cell-dependent and T cell-independent activation

Five asymptomatic human immunodeficiency virus (HIV)-seropositive male homosexuals were immunized with the recall antigens tetanus toxoid (TT) and the three types of poliovirus present in diphtheria, tetanus, and polio vaccine. Four weeks after immunization, the in vivo response to booster immunization, the in vitro pokeweed mitogen (PWM)-induced IgG secretion, and the in vitro T cell-dependent and T cell-independent antigen-induced antibody response were assayed. Increase in serum antibody titer to TT and poliovirus was low and normal, respectively. In all five subjects studied, a high rate of spontaneous IgG production, including antibodies directed toward HIV was observed. Addition of PWM to the cultures induced suppression of the spontaneous IgG secretion. Only one donor showed a slightly increased IgG production after stimulation with PWM. Peripheral blood mononuclear cells of four of the five HIV-seropositive individuals did not produce TT, or poliovirus-specific antibodies when stimulated with the respective T cell-dependent antigens. However, stimulation of these peripheral blood mononuclear cells with TT coupled to agarose beads, which was shown to be T cell-independent, resulted in the generation of IgG anti-TT antibody-forming cells.     

B cell development and regulation after T cell-depleted marrow transplantation

Antibody secreting B lymphocytes from immunized donors can be adoptively transferred after T cell-depleted marrow transplantation to produce protective levels of antibody in the recipient. We have investigated whether these transferred lymphocytes remain subject to continued clonal selection and subsequently became memory B cells even in the initial absence of T cells. Twenty-eight donor/recipient pairs were randomized pretransplant to be immunized or not with tetanus toxoid (TT). The recipients were then vaccinated with TT at 3, 6, and 12 mo posttransplant, and the anti-TT antibody response (IgG and IgM) was measured. Only when both donor and recipient were immunized pretransplant could the recipient respond to antigen challenge within the first year posttransplant. Examination of the spectrotype pattern of the recipient anti-TT antibody shows that selection of B cell clones continues, so that T cell depletion does not prevent the appearance of oligoclonal antibody responses. However, because the spectrotype pattern of the recipient did not match the donors, B cell regulatory mechanisms in donor and recipient are nonidentical. These data contrast with observations made in recipients of non-T cell-depleted marrow and serve to illustrate the role of T lymphocytes in the induction and regulation of secondary antibody responses in man. The results also suggest that optimal humoral responses to any antigen after T cell depletion can only occur when both donor and recipient are immunized pretransplant, a prediction borne out by studies on the influence of donor cytomegalovirus status on the severity of cytomegalovirus infection in the recipient.     

IgG subclasses of anti-tetanus toxoid antibodies in adult and newborn normal subjects and in patients with systemic lupus erythematosus, Sjogren's syndrome, and drug-induced autoimmunity

The IgG subclasses of anti-tetanus toxoid (anti-TT) antibodies were quantitated in normal sera and sera from patients with rheumatic disease. Detection relied on a set of four mouse monoclonal antibodies, each of which showed specificity for the respective isotype, independent of gamma-chain allotype or light chain class of the human antibody. Approximately 90% of the total anti-TT activity in normal adults and patients with Sjogren's syndrome was IgG1. In addition, IgG4 antibodies were detected in one-half the samples, but IgG2 and IgG3 antibodies were observed in only two out of 36 sera. However, antibodies elicited in children immunized with TT were exclusively IgG1 and IgG3, with IgG4 antibodies detectable only at birth (presumably due to transplacental passage of antibody) in three of 12 children. In contrast to normal adults, patients with systemic lupus erythematosus (SLE) and drug-induced autoimmunity (DIA) had a more promiscuous isotype profile. IgG2 and/or IgG3 anti-TT antibodies were detected in 13 of 22 SLE patients and IgG3 antibodies in six of 11 patients with DIA. IgG4 anti-TT antibodies were predominant in seven of these 33 patients. These findings suggest that IgG isotypes may depend on the frequency of the stimulus, but global alterations in immunologic status as reflected in systemic autoimmune disease may override the homeostatic mechanisms that control isotype restriction.     

IgG anti-tetanus toxoid antibody production induced by Epstein-Barr virus from B cells of human marrow transplant recipients

This investigation shows that Epstein-Barr virus (EBV)-activated human B cells from marrow transplant recipients can produce in vitro IgG anti-tetanus toxoid antibody (anti-TT) without booster immunizations with tetanus toxoid (TT). Purified B cells (E-rosette negative) from 8 normal subjects, 6 healthy long-term marrow graft recipients, and 15 long-term marrow graft recipients with chronic graft-vs-host disease (GVHD), were stimulated for 12 days with EBV to induce anti-TT production in culture supernatants. The amount of anti-TT in culture supernatants was quantitated using a enzyme-linked immunosorbent assay. B cells from all 8 normal controls produced in vitro IgG anti-TT after EBV stimulation. Five of 6 healthy recipients had B cells that produced anti-TT after EBV stimulation. Four of 15 recipients with chronic GVHD had B cells capable of producing anti-TT after EBV stimulation. The number of cultures making anti-TT responses was less in those with chronic GVHD than in those without chronic GVHD or normal individuals (P less than 0.001). B cells from patients with chronic GVHD had fewer responses exceeding the overall median of 0.7 ng/ml when compared with the other two groups (P less than 0.03). These data show that B cells of donor origin can produce in vitro IgG anti-TT antibody to tetanus toxoid antigen in a T-independent fashion.     

Autoreactive B cells in normal humans. Autoantibody production upon lymphocyte stimulation with autoantigen-xenoantigen conjugates

Mononuclear cells (MNC) from the blood of healthy individuals cannot be stimulated in vitro with the soluble autoantigen thyroglobulin (Tg). However, when Tg or pepsin fragments of Tg were coupled with a carrier protein, tetanus toxoid (TT), MNC from four healthy TT vaccinated individuals responded to the carrier-autoantigen conjugates by generating anti-Tg antibody forming cells (AFC), as shown in a spot enzyme-linked immunosorbent assay. Generation of anti-TT and anti-Tg AFC after stimulation with the conjugates required the donors to be boostered with TT. The autoantibodies were exclusively of the IgM class, in contrast to the carrier-specific anti-TT antibodies, which were predominantly of the IgG isotype. Activation of normal B cells to anti-Tg production was dependent on the presence of T cells in the cultures and required physical linkage of carrier and autoantigen: no anti-Tg AFC could be detected when MNC were stimulated with uncoupled combinations of Tg and TT. The autoreactive and the carrier-reactive B cells exhibited almost identical conjugate dose-response profiles, which suggest that they responded in a similar way to regulatory signals. These findings indicate that normal blood B cells are competent to respond to the autoantigen Tg in conjunction with signals originating from xeno-antigen-stimulated T cells.     

Assessment in humans of a synthetic peptide-based vaccine against the sporozoite stage of the human malaria parasite, Plasmodium falciparum

Eleven volunteers were injected with an anti-malaria (Plasmodium falciparum) sporozoite vaccine candidate consisting of a synthetic peptide, Ac-Cys-(NANP)3, coupled to tetanus toxoid (TT) and adsorbed to aluminum hydroxide. Two of the volunteers had no previously known exposure to TT. Eight volunteers made detectable antipeptide, anticircumsporozoite protein or antisporozoite antibodies, whose titers increased after multiple injections in four individuals. The maximum antisporozoite titer obtained in an immunofluorescence assay was 1280. In those individuals who produced antipeptide antibody, the overall correlation between IgG anti-Ac-Cys-(NANP)3 antibody in enzyme-linked immunosorbent assay and IgG antisporozoite reactivity in immunofluorescence was highly significant. However, the fine specificity of antibody varied among volunteers with two individuals producing mostly antipeptide antibody. Anti-TT antibody responses increased in all volunteers with the exception of that person who had the highest pretrial anti-TT titer; this individual was one of the two pre-TT-immunized volunteers who failed to produce anti-Ac-Cys-(NANP)3 or sporozoite antibody. For the two non-TT preimmunized volunteers, one produced an antisporozoite fluorescence titer of 320; the other made no detectable antibody against either Ac-Cys-(NANP)3 or sporozoites during a primary response. For the three volunteers monitored, after the first injection, significant T cell proliferative responses to (NANP)3 were observed, which increased up to 4 wk after immunization, when a second injection was given. Responsiveness then declined to background levels and did not reappear after further immunizations. In contrast, a marked TT-specific proliferation was observed for the duration of the study.     

Role of C3 in humoral immunity. Defective antibody production in C3-deficient dogs

Previous studies have shown that animals pharmacologically depleted of C3 have impaired antibody responses. However, such C depletion is neither complete nor sustained, and the C3 cleavage products generated by C3 depletion can both enhance and inhibit the immune response. To clarify the role of C3 in humoral immunity, the antibody response of dogs with genetically determined total deficiency of C3 (C3D) was examined. Serum IgG levels of the C3D animals were within the normal range, but were significantly lower than levels seen in normal controls or C3D heterozygotes. Specific antibody production was defective: the antibody titers of C3D dogs in response to primary intravenous immunization with two different T cell-dependent Ag (sheep E and bacteriophage phi X-174) were markedly reduced when compared to either normal controls or C3D heterozygotes. After secondary immunization with T-dependent Ag, the total antibody titers were normal, but the C3D dogs made proportionately more IgM and less IgG antibody than did either control group. After i.v. immunization with a T cell-independent Ag (DNP-Ficoll), the C3D dogs had reduced levels of IgM and IgG antibody after primary and secondary immunization. Neither i.m. immunization nor the use of a 20-fold increase in Ag dose i.v. could correct the defect seen in the antibody response of C3D dogs. The results herein demonstrate that C3 plays a critical role in the generation of a normal humoral immune response.     

Differential immunosuppressive effects of ascites fluid from mastocytoma-bearing mice on primary vs secondary immunocyte responses.

The effects of immunosuppressive ascites fluids from mastocytoma-bearing mice on the primary vs secondary immune response to sheep red blood cells (SRBC) was examined. Injection of mice with ascites fluid from tumor-bearing mice markedly depressed the primary immune response of normal syngeneic mice challenged with SRBC. However, there was a preferential depression of the 19S IgM antibody response as compared with the 7S IgG response. Injection of ascites fluid shortly before secondary immunization of mice with SRBC also resulted in depressed IgM PFC responses but only a slight to moderate depression of IgG PFC. Treatment of mice with the ascites fluid before primary immunization had little if any effect on the secondary IgG PFC response, although the IgM response was moderately depressed. These results indicate that the immunosuppressive factor(s) present in the ascites fluid of mastocytoma-bearing mice has a differential effect on distinct classes of immunocytes. Those immunocytes or their precursors involved in formation of low efficiency 7S IgG antibody are more resistant to immunodepression. Such differences appear due to different sensitivities of cells involved in the immune response system.     

In vitro human antibody production to the Haemophilus influenzae type b capsular polysaccharide

In vitro production of human antibody to the Haemophilus influenzae type b capsular polysaccharide (PRP) and to tetanus toxoid (TT) and diphtheria toxoid was measured in culture supernatants of peripheral blood mononuclear cells and by enumeration of antibody secreting cells (AbSC) in an enzyme-linked immunosorbent-plaquing assay. Normal adult peripheral blood mononuclear cells stimulated with Epstein-Barr virus secreted anti-PRP antibody with a frequency of 1/552 to 1/1190 relative to total Ig secreting cells; the frequency of AbSC to tetanus toxoid (TT) was 7.5 times higher (p less than 0.05). These frequencies did not change significantly after in vivo immunization, although the isotype distribution shifted toward increased IgG for TT and increased IgG and IgA for PRP. At 8 days postimmunization, spontaneous AbSC to PRP and TT were detected; frequencies for total anti-TT AbSC again being higher than anti-PRP, but there were significantly more IgA plaques among anti-PRP AbSC. Spontaneous AbSC were suppressed in culture by pokeweed mitogen and enhanced by cyclosporine. Three wk after in vivo immunization with PRP and TT, in vitro stimulation with pokeweed mitogen, Staphylococcus aureus Cowan 1 bacteria, or antigen induced anti-TT but not anti-PRP in vitro antibody secretion, although Epstein-Barr virus induced both. These data suggest that PRP, a polysaccharide, and TT, a protein, differ in their requirements for in vitro activation with antigen and mitogens.     

Primary anti-trinitrophenyl memory cells investigated by plaque-forming cells and ELISA.

Primary anti-trinitrophenyl antibody production was investigated from spleen cells of mice immunized with trinitrophenylated-keyhole limpet hemocyanin, using the plaque-forming cell method and ELISA. Cells taken 5 days after antigen injection do not produce IgE, but do produce IgM and IgG1 anti-trinitrophenyl antibodies as demonstrated by plaque-forming cells. Substantial increase of IgM, IgG1, and IgE antibody production was seen from cells taken 7 days after immunization, followed by a rapid decline. By ELISA it was seen that cells taken 3 days after immunization already produce small amounts of anti-trinitrophenyl antibodies. Presence of antigen from the start of the cultures did not increase antibody production from cells taken 3 days after immunization, but potentiated antibody secretions from cells taken 5 days or later after immunization. This potentiation was interpreted as recruitment of antibody-forming cells from early memory B cells. The presence of IL-4 from the start of the cultures had no appreciable effect. Cell sorting with specific antibody-coated magnetic beads showed that plaque-forming cells from nonsorted cells, membrane IgE+ or membrane IgE- cells secreted similar amounts of anti-trinitrophenyl IgG1 and IgE antibodies. No difference in anti-trinitrophenyl IgM, IgG1, or IgE production was found in controls; cells sorted negatively or positively for CD23. The data show that memory B cells can be demonstrated already on Day 5 after immunization, and their antigen-induced antibody secretion is IL-4 dependent.     

Utilization of vitamin A in rats with inflammation

Reductions in the concentration of retinol (vitamin A) in serum, lung and kidney were observed in rats subjected to inflammation-inducing treatments (turpentine oil injection of thermal injury). At the same time, the liver showed an almost normal vitamin A content. Feeding of retinol to vitamin A-depleted rats with inflammation revealed that intestinal absorption of retinol was still active in the inflamed state, and the livers of these rats showed good incorporation of retinol. The livers of normal and vitamin A-depleted rats subjected to the inflammatory treatments showed a normal RBP content (retinol-binding protein) and hepatic release of holo-RBP into the serum was not impaired functionally. These results suggest the possibility that the decreases of vitamin A in the lung, serum and kidney may be due primarily to enhanced local consumption of vitamin A related to the inflammation, rather than to a reduced supply of vitamin A from the liver or to decreased intestinal absorption. In bovine serum albumin (BSA)-sensitized rats produced by direct intubation of BSA into the lungs, the level of vitamin A in the lung decreased prior to that in the liver or serum, supporting the hypothesis that the decrease in vitamin A in the inflamed lungs of these rats may be due mainly to the consumption of vitamin A in the lung in response to inflammation.     

B- and T-lymphocyte responses to an immunodominant epitope of human immunodeficiency virus.

Using synthetic peptides, we characterized the B-lymphocyte (antibody) and T-lymphocyte (proliferation) responses to an immunodominant epitope of human immunodeficiency virus type 1 (HIV-1) located near the amino-terminal end of the transmembrane glycoprotein (env amino acids 598 to 609). Both immunoglobulin M (IgM) and IgG antibodies against this epitope appeared early after primary infection with HIV-1. In an animal model, the IgG response to a synthetic peptide derived from this sequence was T-helper-cell dependent, whereas the IgM response was T-cell independent. In addition, antibody generated by immunization with this peptide had HIV-1-neutralizing activity. Greater than 99% (201 of 203) of patients infected with HIV-1 generated antibody to this peptide in vivo; however, only 24% (7 of 29) had T cells that proliferated in response to this peptide in vitro. These observations suggest that different HIV-1 gp41 epitopes elicit B-cell and T-cell immune responses.     

The relationship between immunization and circulating antigen-specific plaque-forming cells

The relationship between the appearance of cells producing antibody to tetanus toxoid (TT) in the circulation and the serum titers of anti-TT IgG following booster immunization has been studied. It was found that cells producing anti-TT antibody can be detected in the circulation in a hemolytic plaque assay using sheep red blood cells (SRBC) coated with TT by the chromic chloride method. In symmetric inhibition studies using cells from TT or keyhole limpet hemocyanin (KLH)-immune donors, the homologous antigen inhibited 100% of the PFC with no cross-inhibition. Thus, the plaque-forming cells (PFC) detected in this assay are specific for the immunizing antigen. No evidence of polyclonal B-cell activation in response to TT was found, as shown by a failure to detect any PFC against unmodified or KLH or human serum albumin-treated SRBC. In addition, the increase in total Ig-secreting cells observed in a staphylococcal protein A reverse hemolytic plaque assay was always accounted for by the number of anti-TT antibody-producing cells observed. The peak number of anti-TT antibody-producing cells varied between donors, but the kinetics of their appearance was highly reproducible--none before Day 5, peak numbers between Days 6 and 8, and a sharp decline with only rare anti-TT Ig-secreting cells in the circulation by Day 15 postimmunization. Anti-TT antibody-producing cells appeared in the circulation prior to any detectable increase in serum anti-TT antibody titers, and following the disappearance of PFC from the circulation, there was no further increase in serum IgG anti-TT levels. These observations demonstrate a marked specificity of B-cell activation on boosting with a recall antigen, and a parallelism between the appearance of activated B cells in the circulation and of IgG anti-TT synthesis by the subject as a whole.     

Elicitation of antigen-induced primary and secondary murine IgE antibody responses in vitro

Described herein are methods for eliciting and quantitating primary and secondary murine IgE antibody responses in vitro, and the important role of antigen concentration in determining the level of IgE produced during an immune response. The methods for quantitating IgE antibody levels in culture supernatant fluids and in serum by ELISA are presented in detail. The specificity of such methods was confirmed in that (1) no other isotype of antibody registered in the IgE-ELISA, and (2) parallel determinations of IgE antibody concentrations could be obtained by independent analysis using Fc epsilon RI-dependent basophil degranulation. We examined various parameters of cell donor immunization and lymphoid cell culture which allow for optimal in vitro primary and secondary IgE responses. High relative antigen doses result in diminished IgE antibody responses in experimental animals, a finding confirmed herein. High antigen concentrations in vitro also result in relative suppression of IgE antibody synthesis. This was also true for in vitro production of IgG1 and IgA antibodies. Conversely, IgM and IgG2a responses were elicited at both low and high antigen concentrations; IgG2b and IgG3 were not produced under the conditions of priming and culture used herein. Finally, production of IgE in vitro depended on the presence of carrier-primed CD4+ T cells and hapten-specific B cells. Generation of maximal IgE antibody secretion, and hence elicitation of an allergic reaction, is thus dependent on the amount of antigen acting as stimulant for the immune response.     

Anti-IgD enhancement of primary antibody responses in rats

The role of membrane IgD in immune responses was examined by treating adult rats with anti-IgD. Anti-IgD when administered to rats in conjunction with optimal or suboptimal doses of either SRBC, a T-dependent antigen, or DNP-Ficoll, a T-independent antigen, enhanced the antibody responses. The greatest enhancement was obtained when anti-IgD was administered before the antigen. The effects of anti-IgD on antibody responses to SRBC were: (i) significant antibody responses to suboptimal antigen concentrations; (ii) greater antibody responses to optimal antigen concentrations; (iii) accelerated antibody responses; (iv) an early shift from IgM to IgG antibodies; (v) prolonged antibody responses. Similar effects on the immune response to DNP-Ficoll were observed with the exception that all antibodies were 2ME sensitive (IgM). These results suggest that an anamnestic type of immune response can be induced in anti-IgD-treated rats when given a primary antigen exposure. Injection of anti-IgD without SRBC or DNP-Ficoll induces B-cell proliferation without detectable antibody production to these antigens, indicating at least two signals are required for the enhanced antibody responses.     

Activation of a functional idiotype network response by monoclonal antibody specific for a virus (M-MuLV)-induced tumor antigen

BALB/c mice were injected with IgM mAb specific for Moloney murine leukemia virus (M-MuLV)-determined cell surface Ag in an attempt to inhibit Moloney sarcoma growth. The monoclonal IgM significantly inhibited sarcoma growth when given to the mice after inoculation with Moloney murine sarcoma/leukemia virus, and also potentiated the in vivo antibody response specific for M-MuLV Ag. These responses were significantly greater than the primary response to the virus alone in age- and sex-matched control mice, and were also seen in mice which were injected with the IgM antibody only and not with virus, suggesting that an Ag-independent mechanism may be involved. The M-MuLV-specific serum antibody responses induced by the monoclonal IgM, with or without prior virus inoculation, were predominantly of the IgG1 isotype, with some IgG2a; no other isotypes were found to have titers significantly higher than in the normal response to virus alone. M-MuLV-specific IgG1 was detected only in mice injected with monoclonal IgM, and not in the response to virus alone. The same sera also had high titers of anti-idiotypic antibodies, (Ab2), as well as anti-anti-idiotypic antibodies (Ab3). It appears, therefore, that passive immunization with M-MuLV-specific IgM mAb activates an idiotypic network, which results in both Ab2 and Ab3 responses; the M-MuLV-specific response may be considered a subset of Ab3.