IgM-Induced Specific Antibody Responses: Direct Correlation between Responsiveness and Natural or Induced Recurrence of the Idiotype

The idiotype (Id) expressed on antibodies of the trinitrophenol (TNP)-spccific BALB/c hybridoma TNP.11 is defined as a 'nonrecurrent' or private Id in BALB/c mice, whereas the analysis of splenic plaque-forming cells (PFC) and circulating antibody in DBA/2 mice immunized with TNP antigens revealed that TNP.11 is a 'recurrent' Id in this strain. TNP.11 antibodies were characterized by their ability to induce an antigen-independent anti-TNP response in these two strains. Whereas this antibody was negative in BALB/c mice [18], a clearcut increase in splenic anti-TNP PFC, preferentially expressing the TNP.11 Id, was observed in DBA/2 mice. This correlation between Id recurrency and ability to induce antigen-independent responses was further probed in BALB/c mice repeatedly immunized with anti-TNP.11 Id antibodies (Ab3). Such BALB/c mice express the TNP.11 Id in detactable amounts even without antigen challenge and respond with increased numbers of splenic anti-TNP PFC to the injection of low amounts of TNP.11 antibody. These findings suggest that the ability of an antibody to induce antigen-independent PFC responses is associated with the'recurrency', either natural or induced, of the antibody Id.     

Idiotypic characteristics of lambda 1-bearing anti-alpha(1----3)dextran response in wild mice: high frequency of responder strains and co-expression of IdI 558 and IdI 104 on the same molecule

In laboratory mouse strains, only mice with the IghCa phenotype are able to mount an immune response against the alpha(1----3) glycosidic linkage of the B1355 dextran. The response is highly restricted with respect to utilization of only V lambda 1 and few related members of the VH558 family, and characterized by the production of cross-reacting (IdX), and individual (IdI) 104 and 558 idiotopes. We report in this study data showing a large degree of polymorphism in the anti-alpha(1----3)Dex response among 35 wild-derived mouse strains belonging to 4 different species. In contrast to the anti-alpha(1----3)Dex response of common laboratory strains, neither this response nor expression of the IdX, and IdI 104 and 558 idiotopes are linked to the IghCa haplotype. We also demonstrate co-expression on the same molecule of IdI 104 and IdI 558 idiotopes in wild mouse-derived hybridomas. These data challenge the idea of the exclusive expression at the molecular level of IdI 104 or IdI 558.     

Antigen-independent,IgM-induced antibody responses: requirement for “recurrent” idiotypes

Anti-idiotypic antibodies (a-Id) were produced in syngeneic mice against two monoclonal IgM antibodies of BALB/c origin, TNP.11 and SP/603. In plaque inhibition tests, using IgM-secreting hybridoma cells and anti-idiotypic antibodies, these two IgM proteins, as well as the anti-TNP myeloma protein MOPC 460 (IgA) were found to carry non-cross-reactive idiotypes. Analysis of the anti-trinitrophenyl (TNP) plaque-forming cells (PFC) in BALB/c mice, either normal or immunized with TNP-horse red blood cells, revealed that in addition to the MOPC 460 Id, also the SP/603 Id is recurrent and expressed by a fraction of the anti-TNP antibody-secreting cells in all individuals tested. In contrast, the TNP.11 Id could not be detected in any BALB/c mouse studied. TNP.11 and SP/603 antibodies were then characterized by their ability to induce an antigen-independent anti-TNP response in normal BALB/c mice. While TNP.11 was found to be inactive, the same titers of SP/603 IgM induced antigen-specific PFC all of which expressed the SPi603 Id, and increased titers of circulating IgM molecules carrying the same Id, suggesting that “recurrent” but not “nonrecurrent” Id are competent in this respect. A fraction of these SP/603-induced, SP/603-positive anti-TNP antibodies also carried MOPC 460 Id, suggesting expression on the same molecule of idiotypic determinants found on independent non-cross-reactive “recurrent” idiotypes.     

Repertoire of murine lambda-positive variable domains: polyclonal induction of lambda isotypes and their associated pattern of antibody specificities

The diversity of lambda variable (V lambda) domains is extremely restricted when compared to those of VH and V kappa. In addition, each V lambda domain is determined by the C lambda domain. For these reasons, the lambda system is an excellent model for the study of the associated VH region repertoire. The study of V lambda domain diversity has been limited by the small contribution (approximately 5%) of lambda-bearing proteins to the total Ig pool. We now show that treatment of BALB/c mice with rabbit anti-lambda 1 antibodies coupled to lipopolysaccharide induces a production of polyclonal lambda 1 light chain-bearing Ig whereas, conversely, treatment with rabbit anti-lambda 2 antibodies induces a production of polyclonal lambda 2 + lambda 3 light chain-bearing Ig. The antigenic specificities of these two distinct lambda populations were then studied using B1355 dextran, (4-hydroxy-3-nitrophenyl)acetyl (NP) and 2,4-dinitrophenyl (DNP) as antigens. The anti-alpha(1-3)dextran antibody specificity was found to be mediated exclusively by antibodies bearing the lambda 1 isotype whereas the anti-NP and anti-DNP antibody specificities are mediated by both the lambda 1 and lambda 2 + lambda 3 isotypes. In addition, various mouse strains with the VHa or VHb allotypic haplotype and the rlo lambda 1 or r+ lambda 1 phenotype were treated with rabbit anti-lambda 1 antibodies. The lambda 1 anti-NP and anti-DNP antibody specificities were similar in all strains whereas the lambda 1 anti-alpha(1-3)dextran specificity was linked to the presence of the VHa allotypic haplotype. The mouse strains with the rlo lambda 1 or r+ lambda 1 phenotype did not differ in terms of their patterns of lambda 1 antibody specificities.     

xid mice fail to express an anti-dextran immune response but carry alpha(1-3)dextran-specific lymphocytes in their potential repertoire

Even after repeated immunizations with alpha(1-3)dextran (Dex) male (CBA/N x BALB/c)F1 mice fail to produce specific antibodies whereas nondefective female littermates express an idiotype-positive anti-Dex immune response. This failure of xid mice to express serum anti-Dex immunoglobulins is not only limited to immunization with the thymus-independent (TI-2) antigen Dex, since immunization with anti-idiotypic antibodies against Dex-specific idiotypes does not overcome this defect. When xid lymphocytes are cultured in the presence of mitogens, in vitro anti-Dex responses are markedly reduced. We show here that alpha(1-3)Dex-specific hybridomas can be established by fusion of splenic lymphocytes from xid mice to Sp2/0 myeloma cells. Therefore, these mice do carry the potential to generate B cells specific for Dex. All hybridoma antibodies were found to be of IgM isotype, bearing the lambda light chain typical for alpha(1-3)Dex-specific antibodies. Whereas monoclonal anti-Dex antibodies obtained from spleen cell hybridomas from female littermates showed variable idiotope patterns, hybridoma proteins from the immune-defective NBF1-xid mouse expressed only a limited pattern of Dex-specific idiotopes, suggesting that these hybridomas derived from a common precursor.     

Neonatal complement depletion results in predominant expression of a myeloma M 104E private idiotope among anti-dextran antibodies.

Myeloma M 104E (IgM, lambda 1) with specificity for the alpha(1----3) glucosidic linkage of dextran B 1355 S (Dex) carries two idiotopes (Id) as defined by isogenic anti-idiotype mAb. The public Id is not influenced by two amino acid replacements in CDR 2 nor by an alternative D region sequence. It is shared by all or nearly all humoral antibodies in the primary immune response against Dex of mice carrying haplotype Igha. The private Id-5' appears to depend on the integrity of the VH germ-line sequence and on the particular M 104E D region sequence. It is present on a highly fluctuating but usually small fraction of primary anti-Dex antibody. We report here that this situation is changed when mice are treated with Cobra venom anti-complement factor (CVF), after birth and thereby were deprived of complement for the first two weeks of life. When immunized with Dex as adults the majority of anti-Dex Ab carried the M 104E Id-5. Thus, humoral antibody in CVF-treated animals resembled the Ly-1+ anti-Dex precursor B cell population in the peritoneal cavity, while anti-Dex Ab in animals not treated with CVF more closely corresponded to the Ly-1- precursor B cell pool in spleen (H.-P. Lehmann and G. Lehle, Eur. J. Immunol. 1991. 21: 1201).     

Lipopolysaccharide from Brucella abortus behaves as a T-cell-independent type 1 carrier in murine antigen-specific antibody responses.

In order to determine the carrier nature of lipopolysaccharide from Brucella abortus (LPS-BA) in evoking humoral responses, normal and immunodeficient mice were immunized with trinitrophenyl (TNP)-conjugated LPS-BA (TNP-LPS-BA) and the responses were compared with those to known T-dependent and T-independent antigens. TNP-LPS-BA, like T-independent type 1 (TI-1) antigens such as TNP-BA and TNP-LPS from Escherichia coli (TNP-LPS-EC), generated anti-TNP responses in BALB/c, athymic BALB/c nu/nu, and CBA/N mice. In contrast, N-2,4-dinitrophenyl-beta-alanylglycylglycyl-substituted keyhole limpet hemocyanin, a typical T-dependent antigen, was not immunogenic in athymic mice, and TNP-Ficoll (T-independent type 2) was ineffective in eliciting humoral responses in CBA/N mice. These results indicate that LPS from B. abortus acts as a TI-1 carrier in generating antibody responses. In C3H/HeJ mice, TNP-LPS-BA generated higher-titer immunoglobulin G1 (IgG1), IgG2a, and IgG2b anti-TNP antibodies than TNP-LPS-EC. Compared with those from BALB/c mice, pure resting B cells isolated from C3H/HeJ mice exhibited a 30-fold lower proliferative response to LPS-EC, whereas the LPS-BA response was reduced to a lesser extent (5-fold). This suggests that the disparity observed in antibody titers was due to different abilities of LPS from B. abortus and E. coli to stimulate C3H/HeJ B cells. The ability of LPS from B. abortus to act as a carrier in generating humoral immune responses indicates that LPS-BA can be substituted for whole B. abortus organisms in vaccine development.     

Marginal zone of the spleen and the development and localization of specific antibody-forming cells against thymus-dependent and thymus-independent type-2 antigens.

In order to study the precise localization pattern of anti-TNP antibody-forming cells (AFCs) during the early primary immune response against TNP conjugated TD (thymus-dependent) and TI-2 (thymus-independent type-2) antigens, rats received an intravenous injection with either TNP-keyhole limpet haemocyanin (KLH) or with TNP-Ficoll. Anti-TNP AFCs developed in the spleen already at 2 days after injection of the antigens as demonstrated with our immunoenzyme technique for the detection of specific AFCs. In order to obtain information on the relationship between the non-lymphoid cells in the marginal zone (MZ) and the localization of AFCs, simultaneous staining for marginal metallophils and MZ macrophages (MZM) was performed using the monoclonal antibody ED3. AFCs were not found in the marginal zone (MZ), but the bulk of the cells in the white pulp were found in the outer part of the periarteriolar lymphocyte sheaths (PALS) close to the border between PALS and MZ. The precise localization of the anti-TNP AFCs in the outer part of the PALS resembled the localization of marginal metallophils but the latter cells were mainly present in the outer part of the follicles. So, the present results did not indicate a close relationship between marginal zone macrophages or marginal metallophils and anti-TNP AFCs, neither in the immune response to TD antigens nor in that to T1-2 antigens.     

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

In the present study we use two monoclonal anti-idiotope antibodies (Ac38 and Ac146; Ab1) against the germ line-encoded, lambda 1 chain-bearing and (4-hydroxy-3-nitrophenyl)acetyl (NP)-binding antibody B1-8 (Ab1) for the induction of complementary antibodies (Ab3) and ask the question to what extent antibodies bearing B1-8-like idiotopes (Ab3 beta) are represented in the Ab3 population. In this experimental system, Ab3 beta is distinguished from the remaining Ab3 population (Ab3 alpha) by three properties which Ab3 beta may share with B1-8: (a) the binding of NP, (b) the binding to Ac146 (if induced by Ac38) or the binding to Ac38 (if induced by 146) and (c) that they carry lambda 1 chains. Antibodies with all three properties are induced in low amounts by both anti-idiotopes. Also, Ac146 induces only Ab3 alpha (bearing kappa chains and not binding NP and Ac38). In contrast, Ac38 triggers almost exclusively a lambda 1 chain-bearing response, i.e. Ab3 beta. The response has an unusually large size, reaches its maximum after a week and is long-lasting. An analysis at the level of lipopolysaccharide-reactive precursor B cells demonstrates that, in this case, cells expressing Ab3 beta occur at exceedingly high frequency (approximately equal to 10(-3] and are at least 10 times more frequent than cells expressing Ab3 alpha. The high frequency of Ab3 beta-expressing cells correlates with the contribution of several VH, D and J genes to the expression of this particular idiotope. In the case of the Ac146 anti-idiotope antibody, the response is dominated by Ab3 alpha. Ab3 beta represents less than 10% of the total response, reaches maximal levels 2 weeks after immunization and declines rapidly. This correlates with a low frequency of precursor B cells expressing Ab3 beta (approximately equal to 10(-5] and a restriction of the corresponding idiotope to rare VH-D combinations, caused presumably by a stringent contribution of the H chain to this idiotope which covers the NP-binding site. Our data suggest that anti-idiotypic antibodies (Ab2) against Ab1 will preferentially induce antibodies idiotypically related to Ab1 if the corresponding idiotopes are expressed in high frequency in the B cell compartment. This is expected in cases where Ab2 recognizes an idiotope that can be formed by many germ line-encoded VH-D-VL-combinations.     

The J558 V(H) CDR3 region contributes little to antibody avidity; however, it is the recognition element for cognate T cell control of the alpha(1-->3) dextran-specific antibody response [In Process Citation]

Analysis of the humoral immune response of BALB/c mice to alpha(1-->3) dextran (Dex) reveals novel aspects of T cell-mediated control of 'type 2 thymus-independent' responses against polysaccharide antigens. The IgM and IgG antibody response, dominated by the J558 idiotype (Id), is controlled by Id-specific T cells. These regulatory T cells, for which the T cell clone 178-4 Ts with characterized TCR alpha and beta chain sequences is the prototype, expand in all BALB/c mice upon immunization with Dex. They suppress in a cognate interaction the expansion of J558 Id-bearing B cells, committed for production of IgG antibodies. Furthermore they provide a gate which precludes variability in the VH CDR3 region of IgG antibodies appearing occasionally in the periphery. The VH CDR3 region is the recognition element of 178-4 Ts analogous T cells but contributes little to affinity for the antigen. For recognition by 178-4 Ts cells not even minimal sequence deviations of the J558 Id peptide are allowed. The tight germline programmed complementarity between J558 Id-bearing Dex-specific B and J558 Id- specific 178-4 Ts analogous T cells leaves little room on both sides for ontogenetic variability.      

Age-dependent isotype variation during secondary immune response in MRL/lpr mice producing autoanti-gamma-globulin antibodies

A profound inability to produce IgG anti-2,4,6-trinitrophenyl (TNP) antibodies during the secondary immune response elicited by a T-dependent antigen was observed in aged MLR/lpr mice. This unresponsiveness is associated with a significantly low indirect anti-TNP plaque-forming cell response and a weak in vitro anti-TNP response upon the culture of keyhole limpet hemocyanin-primed T cells and TNP-primed B cells in the presence of TNP. The markedly low IgG anti-TNP response observed in aged MLR/lpr mice cannot be related to the presence of rheumatoid factors which are observed during the secondary response, since MRL +/+ and 129/J mice, (non-autoimmune disease strains), also produce significant amounts of anti-gamma-globulin antibodies yet mount a strong IgG anti-TNP response.     

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

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

Mouse monoclonal antibodies at the red cell surface--II. Effect of hapten density on complement fixation and activation

Complement (C)-dependent hemolytic dose-response curves of anti-TNP IgG2b and IgM monoclonal antibodies as a function of TNP density were analyzed: sheep red cells coupled with TNP served as targets. Under conditions when equal numbers of either IgG2b or IgM anti-TNP antibodies were taken up by cells with various TNP densities, both antibodies showed optimal activity at a hapten density of approximately 10(6) TNP/E with regard to C-mediated lysis. These results were similar to those obtained with polyclonal antibodies. The effectiveness of monoclonal antibodies in utilizing guinea pig or mouse C was also investigated. IgM anti-TNP monoclonal antibodies lysed E-TNP in the presence of guinea pig C, but failed to produce lysis in the presence of mouse C. Two monoclonal IgG1 (anti-TNP and anti-SRBC) and an IgG2a anti-TNP antibody failed to produce hemolysis in the presence of guinea pig and mouse C. IgG2b monoclonal antibodies, whether directed against TNP or Forssman antigen, activated guinea pig and, to a lesser extent, mouse C. Finally, monoclonal anti-TNP IgG3 antibodies exhibited a low but measurable hemolytic activity with guinea pig C (10-20 times below that of IgG2b).     

In vivo effects of lipopolysaccharide on lymphoid and non-lymphoid cells in the mouse spleen. Suppressive and adjuvant effects of LPS on the development of specific antibody forming cells in situ

Mice were immunized i.v. with 2,4,6-trinitrophenyl (TNP)-carrier conjugates and received lipopolysaccharide (LPS) before, simultaneously with or after these antigens, in order to study the effects of LPS on the in situ development of anti-TNP antibody forming cells in the spleen. LPS given before, simultaneously with or shortly after the thymus dependent (TD) antigen TNP-keyhole limpet haemocyanin (KLH) suppressed the development of anti-TNP antibody forming cells in the spleen, but serum IgM-anti-TNP titres were not reduced, suggesting a selective inhibiting effect of LPS on the local immune response in the spleen. Splenic responses to thymus independent (TI) antigens TNP-Ficoll and TNP-LPS were not reduced when these antigens were administered one day after LPS. LPS given 4 days after TNP-KLH and 1 day before killing of the animals had induced severe alterations in splenic histology, but we found no marked influence on numbers and distribution pattern of anti-TNP forming cells. Results indicate that the LPS induced suppression of the immune response to TD antigens in the spleen is not caused by a direct effect of LPS on antigen reactive B-lymphocytes or on the anti-TNP antibody forming cells themselves. Possible explanations for the LPS-induced immunosuppression are discussed.     

The T lymphocyte response to syngeneic lambda 2 light chain idiotopes. Significance of individual amino acids revealed by variant lambda 2 chains and idiotope-mimicking chemically synthesized peptides

In the present study we have investigated the structure of the helper T cell (Th)-defined idiotope (Id) of myeloma protein 315 lambda 2 light chain (lambda 2(315] in BALB/c (H-2d) mice which carry a high-responder immune response gene for this Id. Three peptides were synthesized which spanned the third hypervariable region (HV3) of lambda 2(315): peptides 88-99, 94-108 and 91-108. Only peptide 91-108 was capable of eliciting carrier-specific Th that recognized M315 or free lambda 2(315). These Th did not recognize lambda 2(5-7) chain which differs from lambda 2(315) at 4 positions in this region; these are Tyr94, Ser95, Thr96, Tyr98 for lambda 2(5-7) and Phe94, Arg95, Asn96, Phe98 for lambda 2(315). Immunization with peptide analogues revealed that substitution of Tyr for Phe94 was compatible with Id-lambda 2(315) mimicry, but substitution of Ser for Arg95 or Thr for Asn96 destroyed the Th-recognized Id. Furthermore, Th primed with lambda 2(5-7) chain did not cross-react with lambda 2T952; these lambda 2 chains only differ from each other at positions 98 and 99 at the V lambda 2-J lambda 2 junction. The data indicate that individual amino acids of short peptide segments are critical for Th-recognized Id of the lambda 2 HV3 loop and V lambda 2-J lambda 2 junction. Furthermore, the immunogenicity of a small peptide suggests that the carrier (lambda 2)-specific Th recognize Id that have been processed by antigen-presenting cells (APC). This implies the existence of two categories of "internal images" of foreign or of self antigens: (a) serologically defined and (b) T lymphocyte defined. We propose that as a rule, Id processing by APC, including B cells, destroys the first and reveals the second category. The possible physiological function of these Id-specific T cells in network interactions with B cells is discussed.     

Production and immunoselection of IgM-IgA hybridomas: preparing immunoglobulins with dual binding specificity

Fusion between the thioguanine resistant myeloma cell line MOPC-315 [which produces alpha, lambda-2 antibodies specific to the 2,4-dinitrophenyl (DNP) hapten] and a long term in vivo maintained hybridoma 6100.15 [which produces mu, lambda-1 antibodies specific to the 4-hydroxy-3-nitrophenyl acetyl (NP) hapten] resulted in the generation of 12 hybridomas. These hybridomas secrete a mixed family of immunoglobulins (Ig) that bind both DNP and NP and express both IgM and IgA serological determinants. Affinity purified molecules from NP, DNP, anti-mu, or anti-alpha immunosorbents react with both anti-mu and anti-alpha antisera, suggesting that these Ig represent IgM-IgA hybrid molecules. This conclusion was supported by idiotypic analyses. To determine the roles of individual immunoglobulin chains in determining antibody specificity this IgM-IgA hybridoma was used for immunoselection. Following lysis with specific anti-mu and anti-idiotype antibodies, an alpha+, mu- variant clone (A12) was identified, which secreted Ig that binds DNP but not NP. The DNP binding proteins were shown to express alpha, lambda-1 and lambda-2 chains. In contrast, the Ig which lack DNP binding activity only expressed alpha and lambda-1 determinants. The combined results demonstrate that the lambda-1 chain from 6100.15 hybridoma cannot replace lambda-2 of MOPC-315 for DNP binding activity. These data imply that these closely related lambda chains carry sites critical for antigen binding activity. An IgM-IgA hybridoma variant (MA2) which secretes Ig that binds to NP and DNP and expresses mu, alpha and lambda-2 chains was also characterized. This molecule lacked a lambda-1 chain. To determine if the Ig prepared with heterologous mu and lambda-2 chains had NP binding activity required immunoselection of a fourth clone (M2). M2 secretes homogeneous Ig bearing only mu and lambda-2 chains. In contrast to either parental Ig, the M2 antibody molecules express dual binding activity to both NP and DNP. Thus, critical amino acid substitutions in the MOPC-315 lambda-2 sequence are required for DNA binding specificity.     

T-cell enforced invariance of the antibody repertoire in the immune response against a bacterial carbohydrate antigen

The humoral response against the bacterial polysaccharide antigen alpha(1-->3) dextran (Dex) is controlled by J558 idiotype-(Id) specific T cells. These T cells of which the cell clone 178-4 Ts is a representative by all relevant criteria, recognize J558 Id-bearing B cells in an I-Ed-restricted manner. Costimulation via CD28/B7-1 but not via CD40/CD40L leads to T-cell activation. These T cells do not only suppress B cells producing the immunoglobulin (Ig)G3 isotype but also support the survival and clonal expansion of J558 Id positive B cells both in vivo and in vitro. This T-cell mediated dominance of the J558 idiotype limits the appearance of antibodies carrying other more diverse idiotypes which appear in immunized BALB/c nu/nu mice where no regulatory T cells occur. This T-cell mediated antibody invariance could be a strategy of the immune system responding to highly conserved antigens like polysaccharides, different from those against protein antigens, where diversity is assumed to be the basis for a successful response.     

The augmentation of tumor-specific immunity by virus help. I. Demonstration of vaccinia virus-reactive helper T cell activity involved in enhanced induction of cytotoxic T lymphocyte and antibody responses

C3H/He mice were immunized to vaccinia virus by inoculating i.p. viable virus. Their spleen cells (SC) were tested for vaccinia virus-reactive helper T cell activity capable of augmenting (a) anti-trinitrophenyl (TNP) cytotoxic T lymphocyte (CTL) response generated from unprimed C3H/He SC (responding cells) or (b) anti-TNP antibody response generated from TNP-primed C3H/He SC (responding cells) by the stimulation with syngeneic SC infected with vaccinia virus and subsequently modified with TNP (virus-self-TNP). The results demonstrate that cultures of responding cells plus 850 rds X-irradiated vaccinia virus-primed SC failed to enhance anti-TNP CTL or plaque-forming cell (PFC) responses when in vitro stimulation was provided by either virus-self or TNP-self alone. In contrast, these cultures resulted in appreciable augmentation of CTL and PFC responses when stimulated by virus-self-TNP. Such a helper activity provided by vaccinia virus-primed SC was revealed to be T cell mediated and antigen specific. These results are discussed in the context of (a) nature of virus helper antigens, (b) mechanism of help and (c) potential of virus help in augmenting CTL and antibody responses to tumor antigens.     

Genetic polymorphism of lambda 1 and lambda 3 immunoglobulin light chains in the Mus subgenus

Several inbred or partially inbred mouse strains derived from wild mice of different Mus subgroups were surveyed for expression of lambda 1 light chain. One strain, SPE, expressed little or no lambda 1 chains. Two populations of antibodies were obtained by immunization of SPE mice with lambda 1 light chain isolated from the BALB/c J558 (alpha, lambda 1) myeloma protein. One population of antibodies recognized lambda 1 allotypic determinants located on the C terminal fragment beginning at the residue 176. A second population was directed against epitopes present on both lambda 1 and lambda 3 chains. These determinants, which were detected in all strains tested with the exception of SPE, were located in the V region. This result is in concordance with recent DNA studies showing that the lambda 1 and lambda 3 isotype use the same V lambda 1 genes (Blomberg, B. et al., Proc. Natl. Acad. Sci. USA 1981. 78: 3765). Whether the V epitopes recognized by SPE antibodies are allotypic or isotypic in nature is not certain.     

Immune response against the T-independent antigen alpha (1 leads to 3) dextran. I. Demonstration of an unexpected IgG response of athymic and germ-free-raised euthymic BALB/c mice

The primary antibody response in BALB/c mice to the T-independent bacterial antigen dextran B1355S [alpha(1 leads to 3)dextran] (Dex) was studied by means of isoelectric focusing, hemagglutination and immunodiffusion techniques. In response to a single immunization with 10 micrograms Dex all mice produce specific IgM antibodies. In addition, about 30% of conventionally raised BALB/c and BALB/c nu/ + mice, but 95% of germ-free (GF)-raised normal BALB/c and 100% of athymic BALB/c nu/nu mice produce specific IgG class anti-Dex antibodies. These antibodies include all IgG subclasses, carry predominantly the lambda light chain and the cross-reactive J558 idiotype and are specific for the alpha(1 leads to 3)glucosidic linkage. As compared to athymic and GF-raised mice, conventionally raised mice exhibit only a weak IgG response. The pronounced IgG production of GF-raised mice was not altered when adult mice were removed from their GF environment and housed under conventional conditions for several weeks prior to immunization with Dex. Reconstitution with isolated splenic T cells from conventionally raised, unprimed BALB/c mice reduces the remarkable capacity of BALB/c nu/nu mice to produce IgG anti-Dex antibodies. These findings suggest that the reduced capacity of conventionally raised BALB/c mice to mount an IgG response to the T-independent antigen Dex is due to a T cell-mediated suppressive mechanism which is neonatally induced by contact with environmental, i.e. bacterial, antigens.