Genetic control of the antibody response. II. Further analysis of the specificity of determinant-specific control, and genetic analysis of the response to (H,G)-A--L in CBA and C57 mice.

CBA and C57 mice were tested for their ability to make an immune response to a related series of branched, multichain synthetic polypeptide antigens in which the antigenic determinants on the amino termini of the branched side chains were systematically varied. Neither strain responded to the polyglutamic acid determinant. Both strains responded well and equally to the poly(phenylalanine, glutamic acid) determinants. CBA mice responded poorly, and C57 mice responded well to two different antigens bearing poly(tyrosine, glutamic acid) determinants. CBA mice responded well, and CS7 mice responded poorly to two different antigens bearing poly(histidine, glutamic acid) determinants. The genetic control of the immune response to (H,G)-A--L appears to be dominant and polygenic, as it has been shown to be for (T,G)-A--L. The related antigens used in this study show extensive cross-reactions with antisera against other members of the related series.

Genetic control of the immune response: in vitro stimulation of lymphocytes by (T,G)-A--L, (H,G)-A--L, and (Phe,G)-A--L.

In vitro antigen-induced tritiated thymidine uptake has been used to study the response of sensitized lymphocytes to (T,G)-A--L, (H,G)-A--L, and (Phe,G)-A--L in responder and nonresponder strains of mice. The reaction is T-cell and macrophage dependent. Highly purified T cells (91% Thy 1.2 positive) are also responsive, suggesting that this in vitro lymphocyte transformation system is not B-cell dependent. Lymphocytes from high and low responder mice stimulated in vitro react as responders and nonresponders in a pattern identical to that seen with in vivo immunization. Stimulation occurs only if soluble antigen is added at physiological temperatures; antigen exposure at 4 degrees C followed by washing and incubation at 37 degrees C fails to induce lymphocyte transformation. Stimulation is specific for the immunizing antigen and does not exhibit the serologic cross-reactivity which is characteristic of these three antigens and their respective antisera. The reaction can be inhibited by anti-H-2 sera but not by anti-immunoglobulin sera. The anti-immunoglobulin sera did, however, inhibit lipopolysaccharide or pokeweed mitogen stimulation. These results suggest that the Ir-1A gene(s) are expressed in T cells, and that there are fundamental physiologic differences between T- and B-cell antigen recognition.

Comparative analysis of antigen-binding T cells in genetic high and low responder mice.

[(125)I](T,G)-A--L-binding T cells have been studied in mice whose ability to mount an immune response to (T,G)-A--L is under control of the H-2-linked Ir-1A gene. Nonimmunized high and low responder mice have approximately the same frequency of T-ABC. Following immunization, T-ABC proliferated only in high responders, but not in low responders, indicating expression of Ir-1A in T cells. When, for comparison, [(125)I]arsanyl-mouse serum albumin binding B and T cells were investigated in mice whose antibody response to the hapten arsanyl is controlled by an allotype-linked Ir gene, it was found that following immunization the number of B-ABC increased only in high responders. In contrast, T-ABC proliferated to the same extent in both high and low responders, suggesting exclusive expression of the allotype-linked Ir gene in the B-cell line. Preliminary studies indicate that anti-Ia sera inhibit neither B-ABC nor T-ABC.

I-region genes are expressed on T and B lymphocytes. Studies of the mixed lymphocyte reaction (MLR).

Unidirectional mixed lymphocyte reactions (MLR) were performed between mouse strains differing for various segments within the H-2 complex. Thymocytes and purified lymph node T cells and B cells were used as stimulator cells. In three of five combinations studied, differing only within the I region, both T and B cells stimulated in the MLR. This suggests that the region codes for both T- and B-cell surface structures. However, if the difference was restricted to one I subregion (I-C), only T cells stimulated. This finding suggests that some of the I-region genes may be expressed either in T or in B cells.

Characterization of HLA-D-region antigens by two-dimensional gel electrophoresis. Molecular-genotyping.

Monoclonal antibodies directed against nonpolymorphic determinants of HLA-D/DR molecular complex (human Ia antigens) were used to immunoprecipitate HLA-D-region-associated molecules from [35S]methionine internally labeled and 125I surface-labeled B lymphoblastoid B cell lines. Analysis of these by two-dimensional nonequilibrium-pH-gradient electrophoresis reveals a molecular heterogeneity within a 26,000- to 34,000-mol wt range. At least three sets of spots are identified: a very acidic set of 32,000- to 34,000-mol wt, a very intense invariant spot of 31,000 mol wt, and a series of 26,000- to 29,000-mol wt spots of variable charge. Comparison of immunoprecipitates from nine different HTC demonstrates that the polymorphism is localized in this latter set. Pulse-labeling and inhibition of glycosylation by tunicamycin show that the electrophoretic polymorphism is of polypeptide origin, whereas N-linked oligosaccharrides and sialic acid residues contribute to the microheterogeneity of the profile. Two-dimensional gels provide an electrophoretic genotyping procedure and allow analysis of the genetic organization and molecular complexity of the HLA-D/DR molecules.

Genetic control of the antibody response in inbred mice. Transfer of response by spleen cells and linkage to the major histocompatibility (H-2) locus.

The transfer of spleen cells from (C3H x C57Bl/6) F(1) mice, capable of responding to (T,G)-A--L, into irradiated C3H parental recipients, normally incapable of responding to (T,G)-A--L, transfers the ability to make either a primary or secondary immune response to this synthetic polypeptide antigen. This localizes the genetic control of the ability to respond to the spleen cell population and indicates that the genetic control is exerted upon a process directly related to antibody formation. Studies with congenic strains of mice and linkage studies in segregating backcross populations show that the ability to respond to (T,G)-A--L and (H,G)-A--L is linked to the H-2 locus and can thus be localized to the IXth mouse linkage group. Note Added in Proof: Of the three possible recombinant animals noted in Tables IV and V, two were infertile. The third animal was not a recombinant, since progeny testing and reimmunization showed that this animal was an H-2(2)/H-2(k) heterozygote capable of responding well to (T,G)-A--L.

Expression of a single major histocompatibility complex locus controls the immune response to poly-L-(tyrosine, glutamic acid)-poly-DL-alanine-poly-L-lysine.

Genetic control of the immune response linked to the major histocompatibility (H-2) complex in the mouse has been described for synthetic polypeptide antigens and for low doses of native proteins. The phenomenon is well documented(1,2). Extensive screening of intra-H-2 crossover-derived recombinant strains has localized H-2-linked immune response (Ir) genes to the I-immune response region of the H-2 complex (3). For most antigens, Ir genes are autosomal, dominant, and they segregate as single loci. It is not known whether these crossover-defined loci respresent single genes with multiple alleles or clusters of tightly linked genes (4). In 1972, Stimpfling and Durham (5) postulated that two interacting loci within the H-2 complex were required for the response to the alloantigen, H-2.2 (6), and, in 1975, Dorf et. al. (7) observed a responder phenotype in a recombinant derived from two strains which were nonresponders to the synthetic linear terpolymer, L-glutamic acid, L-lysine, L-phenylaline (GLPhe). Analysis of additional recombinants and complementation tests with F(1) hybrids clearly demonstrated that genes in two intra-I-region loci controlled the immune response to GLPhe. Subsequently, requirement for genes mapping in two intra-I-region loci were reported for porcine LDH(B)(8), the alloantigen Thy-1.1 (9), and for the synthetic terpolymers L-glutamic acid, L-lysine, L-tyrosine and L-glutamic acid, L-lysine, L- leucine (6,10). Demonstration that responses to both synthetic polypeptide and native protein antigens can be controlled by genes in two distinct I-region loci prompted speculation that the phenotypic expression of two I-region genes is a general phenomenon which may provide the key for understanding the mechanism of Ir gene function and cellular collaboration in the immune response. Benacerraf and Dorf (10) have shown that Ir gene complementation is often more effective in the cis than in the trans configuration. This concept is further supported by the data reported for GLPhe (10-12) which indicate that both of the complementing genes must be expressed in each of the cell types participating in the interaction. Failure to detect complementation for the majority of antigens under H-2-linked Ir-gene control might be attributed to the limited number of available intra-I- region recombinant strains.

Antibody response of C3H in equilibrium (CKB X CWB)F1 tetraparental mice to poly-L(Tyr,Glu)-poly-D,L-Ala-poly-L-Lys immunization.

To test whether the antigen-specific stimulation of low responder-genotype B cells in tetraparental mice is due to a histoincompatibility reaction (allogeneic effect) against these B cells, tetraparental mice were constructed (a) between an Ir-1A low responder to the antigen poly-L(Tyr,Glu)-poly-D,L-Ala--poly-L-Lys. [(T,G)-A--L] and an Ir-1A F1 high responder and (b) between two histoincompatible Ir-lA low responders. In the first case the F1 high responder embryo shares the whole of the H-2 complex, including Ir, with the low responder embryo.

Genetic control of the immune response. Frequency and characteristics of antigen-binding cells in high and low responder mice.

The influence of immunization with (T,G)-A--L on the frequency and characteristics of [(125)I] (T,G)-A--L-binding cells (ABC) was investigated in high and low responder mice, whose ability to respond to (T,G)-A--L is under control of an H-2-linked immune response gene, Ir-1. Unimmunized high and low responder mice have about the same number of ABC in spleen and lymph nodes (6-12 ABC/10(4)). However, after immunization with (T,G)-A--L in aqueous solution, ABC in high responders increase to a much greater extent than they do in low responders. By inhibition of ABC with class-specific anti-Ig sera, it was demonstrated that in nonimmune and primed mice antigen is bound to IgM receptors, which is in agreement with the exclusive production of 19S anti-(T,G)-A--L antibody in primed animals. In contrast, after secondary challenge with antigen, ABC in high and low responder mice have mainly IgG receptors, although under the conditions used for immunization, low responders are not able to produce detectable amounts of 7S anti-(T,G)-A--L antibody. From these results and from the evidence that low responders very probably have a T cell defect, it is suggested that the switchover from IgM to IgG precursor cells can be induced by antigen itself, without the action of specific T cells. Furthermore, the failure of marked proliferation of ABC in low responders after antigenic stimulation is explained by the lack of stimulation by specific T cells. By independent methods it has been shown that all ABC detected in this study are B cells. Preliminary experiments indicate that purified peripheral T cells bind antigen, but much less per cell than do B cells.

In vitro analysis of allogeneic lymphocyte interaction. I. Characterization and cellular origin of an Ia-positive helper factor-allogeneic effect factor.

A soluble allogeneic effect factor (AEF) was produced by using H-2 congenic mouse strains and a serum.free cell culture medium. An AEF derived from untreated activated responder cells and irradiated stimulator cells provided helper cell function in a primary and secondary antibody response for both T-cell-depleted responder B cells and stimulator B cells. This interaction may be determined by genes situated in the I-A and I-B regions: additional K-region control was not excluded. Ia antigens, but neither H-2 nor Ig determinants are molecular constituents of AEF. The active components of this AEF consist, in part, of Ia antigens derived from both the activated responder cell population and irradiated stimulator cell population. An AEF derived from Ia negative responder cells and irradiated T-cell- depleted stimulator cells helps a secondary antibody response of T-cell- depleted stimulator B cells but not responder B cells. This genetically restricted AEF contains Ia antigens determined by the stimulator haplotype but not the responder haplotype. The priming antigen, DNP- keyhole limpet hemocyanin, is not a component of restricted AEF. The data suggest that restricted AEF may be a product of a stimulator B cell and/or macrophage. They support the hypothesis that the recognition by allogeneic T cells of Ia antigens on B cells activates the B cell to IgG antibody production.

Genetic control of cell-mediated responsiveness to an AKR tumor-associated antigen: mapping of the locus involved to the I region of the H-2 complex.

The role of H-2-linked genes in controlling resistance to murine leukemia viruses has been studied by measuring the cell-mediated immune response of F1 hybrid mice (between AKR and various C3H and C57BL/10 derived, H-2 congenic strains) to an AKR tumor cell line, BW5147. The studies have shown that the ability to generate a primary or secondary cell-mediated response to an AKR tumor cell antigenic determinant is under H-2 linked control. The locus determining CML responsiveness maps in the I-J subregion. Nonresponsiveness is associated with the H-2q/k and H-2b/k hybrid genotypes, whereas responsiveness is associated with the H-2k/k homozygous genotype. Nonresponsiveness may result from (a) dominant suppression; (b) recessive responsiveness; or (c) an alternate mechanism not yet understood. This type of control may be one of several H-2-associated mechanisms of defense against virus-induced neoplasms.

Allotype-specific analysis of anti-(Tyr,Glu)-Ala-Lys antibodies produced by Ir-1A high and low responder chimeric mice.

Katz et al. (1) have demonstrated a restriction in lymphoid cell interaction when the antigen used is under immune response (Ir) gene control. T cells from (low responder x high responder) F(1) mice primed to the terpolymer L-glutamic acid, L-lysine, L-tyrosine (GLT) can collaborate with 2,4-dinitrophenyl (DNP)-primed B cells from the Ir-GLT high responder but not low responder strain in response to DNP-GLT (1). In contrast are the studies of Bechtol et al. and Bechtol and McDevitt (2,3), who examined the antibody responses of tetraparental mice immunized with the synthetic polypeptide poly-L(Tyr,Glu)-poly D,L-Ala- poly-L-Lys ((T,G)-A-L), an antigen under Ir-1A genetic control. Several tetraparental mice produced anti(T-,G)-A-L antibody of low responder strain immunoglobulin (Ig) allotype (2,3). These results indicated that he Ir-1A gene was not expressed in B cells and implied that interactions among genetically dissimilar cell populations could occur when tolerance existed to H-2 antigenic differences. Recent studies with bone marrow cell chimeric mice have shown that chimeric T cells can interact with H-2 histoincompatible B cells in response to antigens not under Ir gene control (4-6). To clarify whether lymphoid cell chimerism, with presumed tolerance to H-2 incompatibility, would permit effective cell interactions in response to antigens under Ir gene control, bone marrow cell chimeric mice were prepared by using strains differing both for Ig allotype and for high versus low responsiveness to (T,G)-A-L. An antigen-specific and allotype- specific antibody assay was used to discriminate the responses produced by high and low responder strain B cells in these chimeras. The results suggest that lymphoid cell chimerism per se is not sufficient to obviate Ir gene-mediated restriction in cell interaction.

Murine t factors: an association between alleles at t and at H-2.

Lymphocytes from tx-mutant mice have a definite and consistent pattern of reactivity in MLR. Cells from t-mutant mice within a complementation group usually fail to stimulate each other, while cells from mutants in different complementation groups stimulate each other strongly. This indicates that tx-mutant types are associated with certain H-2 haplotypes, and that members of any give complementation group share the same H-2 haplotype.

In vivo treatment of (NZB X NZW)F1 lupus-like nephritis with monoclonal antibody to gamma interferon.

The (NZB X NZW)F1 mouse is recognized as an important animal model of the human disease systemic lupus erythematosus (SLE). Groups of NZB/W F1 mice were treated either with IFN-gamma or with PBS. The results demonstrate that IFN-treated animals have accelerated development of fatal immune complex glomerulonephritis relative to age-matched controls. On the other hand, administration of mAbs specific for IFN-gamma to such mice from 4 to 7 mo of age resulted in significant remission. Development of both proteinuria and anti-DNA antibodies were delayed and survival at 11 mo was increased from less than 20% to 95% in treated mice relative to controls (p less than or equal to 0.001). These findings may have therapeutic implications for the treatment of SLE.

Induction of apoptosis and T helper 2 (Th2) responses correlates with peptide affinity for the major histocompatibility complex in self-reactive T cell receptor transgenic mice.

Multiple sclerosis is an autoimmune disease thought to be mediated by CD4+ T helper cells (Th). Experimental autoimmune encephalomyelitis is a rodent model of multiple sclerosis and has been used extensively to explore a variety of immunotherapies using soluble protein or peptide antigens. The underlying mechanisms of such therapy have been attributed to induction of T cell anergy, a switch in Th1 to Th2 responses, or peripheral deletion of autoreactive T cells. In this study, we have developed transgenic mice expressing a T cell receptor (TCR) specific for the NH2-terminal peptide Ac1-11 of the autoantigen myelin basic protein to explore the mechanism of soluble peptide therapy. T cells from these mice are highly skewed toward the CD4 population and have an abnormal thymic architecture, a phenomenon found in other TCR transgenic mice that exhibit a highly skewed CD4/CD8 ratio. Soluble Ac1-11 or the analogues Ac 1-11 [4A] or Ac1-11[4Y] (which bind to the major histocompatibility complex [MHC] class II molecule I-Au with increasing affinities) given intravenously activates T cells, rendering cells hyperresponsive in vitro for at least two days after injection. Concomitantly, T cells apoptose in the periphery, the degree of which correlates with the affinity of the peptide for the MHC. In addition, a shift in the T helper phenotype of the surviving T cells occurs such that the low affinity peptide, Ac1-11, induces primarily a Th1 response, whereas the highest affinity peptide, Ac1-11[4Y], induces primarily a Th2 type response. These data show that both the nature and the presumed number of the peptide-MHC complexes formed during specific peptide therapy affect both the degree of peripheral programmed cell death as well as the outcome of the T helper subset response in vivo, leading to amelioration of disease.

Treatment of (NZB x NZW)F1 disease with anti-I-A monoclonal antibodies.

(NZB x NZW)F1 mice spontaneously develop an autoimmune syndrome characterized by a fatal immune complex glomerulonephritis. Administration of monoclonal antibodies specific for an I region gene product (I-Az) of the H-2 haplotype associated with susceptibility to glomerulonephritis in these animals produced a remission in female mice with established renal disease. The results demonstrated that anti-I-A therapy stabilized the level of proteinuria and increased the 1-yr survival rate from 10% to greater than 90% in treated animals relative to control mice. These findings may ultimately have therapeutic potential for the treatment of systemic lupus erythematosus.

Gene conversion between murine class II major histocompatibility complex loci. Functional and molecular evidence from the bm 12 mutant.

The experiments presented in this study define the molecular basis of the bm 12 mutation. Initial characterization of an alloreactive T cell clone, 4.1.4, showed this clone to recognize an allodeterminant present on the E beta b and A beta bm12 chains, but not on the bm 12 parent A beta b chain. To define the extent of sequence shared between the I-E beta product and the mutant I-A beta product, we isolated a cDNA clone of the E beta b gene and determined its nucleotide sequence. Comparison of the nucleotide sequences of E beta b, A beta b, and A beta bm12 shows the the A beta bm12 gene to be identical to the E beta b gene in the region where it differs from its A beta b parent. We predict that the bm 12 mutation arose by gene conversion of this region, which spans 14 nucleotides between amino acid residues 67-71 of the mature A beta chain, from the E beta b locus to the corresponding position at the A beta b locus. Recognition of this region, which spans one of the previously defined E beta allelic "hypervariable" regions, by an alloreactive T cell clone provides the first direct evidence of the functional importance of these hypervariable regions in T cell stimulation. The identification of a gene conversion event involving one of these allelic variable regions implicates conversion as a mechanism that acts on class II beta genes to create sequence diversity in regions of Ia molecules that interact with foreign antigen or a T cell receptor, regions where protein sequence polymorphism would presumably be selected for by the expanded ability it affords the organism to mount effective immune responses against a wider variety of foreign antigens.

The genetic control of antibody specificity.

The immune response to a synthetic polypeptide built on multichain polyproline, poly-L-(Tyr,Glu)-poly-L-Pro-poly-L-Lys [(T,G)-Pro--L], in the offspring of a cross between DBA/1 and SJL mice is under a genetic control superficially similar to the one operating for the immune response to a similar synthetic polypeptide built on multichain polyalanine, poly-L-(Tyr,Glu)-poly-D,L-Ala-poly-L-Lys [(T,G)-A--L], in the offspring of a cross between CBA and C57 mice. In both cases, the genetic control is a quantitative trait in which the major gene(s) is (are) dominant and the trait is not linked to any of the known structural genes coding for mouse immunoglobulin heavy chains. However, the genetic control of response to (T, G)-Pro--L, designated immune response-3 (Ir-3), is qualitatively different from the one operating for (T,G)-A--L [immune response-1 (Ir-1)] in that it is not linked to the histocompatibility-2 (H-2) locus. A study of the immune response to a related polypeptide built on multichain polyproline, poly-L-(Phe,Glu)-poly-L-Pro-poly-L--Lys [(Phe, G)-Pro--L], in the DBA/1 x SJL cross has shown a genetic control of antibody specificity. F(1) x DBA/1 backcross anti-(Phe, G)-Pro--L sera segregate in their ability to bind (T,G)-Pro--L, and there is no linkage of anti-(T,G)-Pro--L binding capacity with the H-2(s) allele of the SJL grandparent. F(1) x SJL anti-(Phe, G)-Pro-L sera segregate in their capacity to bind poly-L-(Phe,Glu)-poly-D,L-Ala-poly-L-Lys [(Phe, G)-A--L] and the ability to bind (Phe, G)-A--L is clearly linked to the H-2(q) allele from the DBA/1 grandparent. Thus, in mice all responding well to a given antigen [(Phe, G)-Pro--L], the specificity of the antibodies produced [i.e., anti-(Phe,G) or anti-prolyl] is genetically determined. Cross-inhibition of binding m (DBA/1 x SJL)F(1) anti-(Phe,G)-Pro--L antisera indicates that the anti-(Phe,G) and anti-prolyl specificities are a function of two separate and largely non-crossreacting antibody populations.

Two-gene control of the expression of a murine Ia antigen.

Two dimensional polyacrylamide gel electrophoresis of Non-Idet P-40 extracts and of specific Ia immunoprecipitates from [35S]methionine-labeled mouse spleen lymphocytes has revealed that the cell surface expression of some Ia antigens appears to be controlled by two genes. One locus, which maps in the I-A subregion, is probably the structural gene for an Ia polypeptide chain. The second locus, which maps between the I-J and H-2D regions, controls whether this I-A encoded molecule (Ae) remains in the cytoplasm or is modified and expressed on the cell surface. Complementation between these two loci allowing surface expression of Ae can occur in the cis or trans chromosomal position. Both the I-A molecule and a polypeptide chain coded for by a locus in I-E are coprecipitated by anti-I-E antibodies, suggesting that these two chains are associated with each other as a multisubunit complex in the cell. Because the ability to complement I-A for Ae expression is a property only of those strains which synthesize an I-E-encoded protein, it is likely that the I-E product itself is regulating the expression of Ae. These observations suggest several mechanisms by which interaction between two I region loci can generate new cell surface molecules. As a result, they may have important implications for understanding the molecular basis of two gene control of immune responsiveness and immune suppression.

Suppression of the mixed lymphocyte reaction in man by a soluble T-cell factor. Specificity of the factor for both responder and stimulator.

J.H., an HLA-Dw2 homozygous multiparous woman, fails to respond to her husband, W.H. (HLA Dw1,-) in the unidirectional mixed lymphocyte reaction. T cells from J.H. were previously shown to suppress the responses of Dw2-positive cells but not Dw2-negative cells to W.H. We now report that a soluble factor released into the supernate of the mixed lymphocyte reaction by J.H. T cells, mediates this suppression. Like the cell from which it is derived, the factor is highly specific for HLA Dw2 in the responder cell and partially specific for the stimulatory alloantigen.