GENETIC CONTROL OF IMMUNE RESPONSES IN VITRO : IV. CONDITIONS FOR COOPERATIVE INTERACTIONS BETWEEN NONRESPONDER PARENTAL B CELLS AND PRIMED (RESPONDER x NONRESPONDER) F1 T CELLS IN THE DEVELOPMENT OF AN ANTIBODY RESPONSE UNDERIr GENE CONTROL IN VITRO

The conditions for cooperative interactions between nonresponder B10.S B cells and GAT-primed irradiated (C57BL/6 x SJL)F₁ T cells in the response by cultures of mouse spleen cells to GAT were investigated. GAT-specific antibody responses could be elicited by soluble GAT in cultures of GAT-primed irradiated (C57BL/6 x SJL)F₁ T cells with C57BL/6 B cells but not with B10.S B cells. In contrast, when GAT was presented to the cultures on F₁ macrophages or as aggregates of GAT with MBSA, GAT-specific PFC responses were observed with both B10.S or C57BL/6 B cells. Irradiated GAT-primed T cells were nevertheless essential for the development of these responses. The GAT-specific response of B10.S B cells in these cultures was inhibited by the addition of soluble GAT at culture initiation. These results indicate that genetic disparity at Ir loci is not an absolute barrier to T-B-cell cooperative interactions in the response to antigens under Ir gene control. The significance of these data for the function of Ir gene products in immunocompetent cells is discussed.     

ONTOGENY OF B LYMPHOCYTES : III. H-2 LINKAGE OF A GENE CONTROLLING THE RATE OF APPEARANCE OF COMPLEMENT RECEPTOR LYMPHOCYTES

The frequency of lymphocytes bearing complement receptors in the spleens of 2-wk old mice appears to be controlled by two independent genes. The presence of a "high" allele at either locus leads to intermediate or high frequency of CRL at 2 wk of age. One of the genes controlling complement receptor lymphocyte (CRL) frequency (CRL-1) is linked to the H-2 complex. Thus, in progeny of (AKR x DBA/2)F₁ x DBA/2, all mice with a low frequency of CRL at 2 wk of age are homozygous for the H-2 type of the low CRL parent (DBA/2). Furthermore, in the B10 series of congenic mice, CRL frequency at 2 wk of age is similar to the frequency in the donor of the H-2 region. Thus, C57BL/10, B10.BR, and B10-D2 mice are all of the low CRL type while B10.A mice are intermediate in CRL frequency at 2 wk. C57BR and DBA/2, the donors of the H-2 complex of the B10.BR and B10.D2, respectively, are of low CRL type while the A/WySn, the donor of the H-2 complex in the B10.A, is an intermediate CRL strain. Similarly in the A/WySn series of congenic mice, A.CA, A.SW, and A.BY are all low CRL strains while the A/WySn is intermediate. Studies of CRL frequency in mice with recombinant H-2 chromosomes (B10.A(2R), (4R), and (5R); B6/TL⁺; and A/TL^-) indicate that CRL-1 is to the right of the Ss-Slp genes and to the left of Tla.     

GENETIC CONTROL OF BONE MARROW GRAFT REJECTION : I. DETERMINANT-SPECIFIC DIFFERENCE OF REACTIVITY IN TWO PAIRS OF INBRED MOUSE STRAINS

Transplantation of 5 x 10⁵ DBA/2 (H-2^d) bone marrow cells into irradiated B10 and 129-strain mice (both H-2^b) resulted in graft failure in the first recipient strain and in graft take in the second. Transplantation of B10 (H-2^b) cells into irradiated B10.BR and C3H mice (both H-2^k) also resulted in failure in the congenic B10.BR recipients and take in the C3H mice. Resistance and susceptibility of B10 and 129-strain animals were specific for given H-2 alleles of donor cells. Transplantation of DBA/2 marrow into (B10 x 129)F₂ mice and of B10 marrow into (B10.BR x C3H)F₁ x C3H backcross mice revealed definite genetic control of the graft-rejection process, presumably at the level of alloantigen recognition. Resistance to allografts, or responder status, was conferred upon segregating mice by dominant alleles of two major independent autosomal loci. The effects of the loci were additive. Conversely, susceptibility to allografts, or nonresponder status, was due to the apparently recessive alleles of both loci. None of the genes was closely linked with the markers tf (tufted) and T (brachyury) of linkage group IX, A^w (white-bellied agouti) of linkage group V, Sl (steel) of linkage group IV, and c^ch (chinchilla) and p (pink eye, dilute) of linkage group I. There were suggestions, however, that the regulator genes of marrow graft rejection are either non-H-2 histocompatibility genes or other genetic factors closely linked with them.     

CELLULAR BASIS OF THE GENETIC CONTROL OF IMMUNE RESPONSES TO SYNTHETIC POLYPEPTIDES : I. DIFFERENCES IN FREQUENCY OF SPLENIC PRECURSOR CELLS SPECIFIC FOR A SYNTHETIC POLYPEPTIDE DERIVED FROM MULTICHAIN POLYPROLINE ([T, G]-PRO--L) IN HIGH AND LOW RESPONDER INBRED MOUSE STRAINS

SJL mice are high responders to the synthetic multichain polypeptide antigen (T,G)-Pro--L, whereas DBA/1 mice are low responders (10, 11). In order to determine whether the genetic control of immune response can be correlated with the number of antigen-sensitive precursor cells, spleen cell suspensions from normal and immunized SJL and DBA/1 donor mice were transplanted into lethally X-irradiated syngeneic recipients (incapable of immune response) along with (T, G)-Pro--L. Anti-(T, G)-Pro--L responses (donor-derived) were assayed in the sera of the hosts 12–16 days later. By transplanting graded and limiting numbers of spleen cells, inocula were found which contained one or a few antigen-sensitive precursors reactive with the immunogen. Using this method to estimate the relative numbers of such cells for the high responder SJL strain, one precursor was detected in ~1.3 x 10⁶ and ~7.2 x 10⁶ spleen cells from immunized and normal donors, respectively. In contrast, one precursor was detected in about 30 x 10⁶ spleen cells from low responder DBA/1 mice, irrespective of whether the donors had been immunized. These results indicate that the genetic control of immunity to the synthetic polypeptide antigen investigated is directly correlated to the relative number of precursor cells reactive with the immunogen in high and low responder strains.     

CELL INTERACTIONS BETWEEN HISTOINCOMPATIBLE T AND B LYMPHOCYTES : IV. INVOLVEMENT OF THE IMMUNE RESPONSE (Ir) GENE IN THE CONTROL OF LYMPHOCYTE INTERACTIONS IN RESPONSES CONTROLLED BY THE GENE

In the present study we have asked the question of whether F₁ carrier-primed T cells can serve as helper cells for either or both parental B cells when (a) the carrier molecule employed is under genetic control such that one parental strain is a responder and the other is a nonresponder, and (b) the determinant specificity of the parental B cells being assessed is not under genetic control and bears no relationship to the specificity of the carrier molecule. Utilizing the system of immune response gene control of responses to the terpolymer L-glutamic acid-L-lysine-L-tyrosine (GLT) to which A strain mice (H-2^a) are nonresponders, whereas BALB/c (H-2^d) and (BALB/c x A)F₁ hybrids (CAF₁) are responders, these studies demonstrate that GLT-primed T cells of CAF₁ donors can provide for responder BALB/c, but not for nonresponder A/J, the required stimulus for the anti-DNP responses of DNP-specific B cells of these respective parental strains to the DNP conjugate of GLT. The implications of these findings for Ir gene function in physiologic T-B cell interactions are discussed in detail.     

SEROLOGIC EVIDENCE FOR ANTIGENS CONTROLLED BY THE Ir REGION IN MICE

Antibodies produced in B10.D2 mice against soluble lymphocyte membrane antigens of B10.A (H-2^a) mice reacted only with lymphocytes of the strains carrying the Ir^k region, i.e., B10.A(2R), B10.K, B10.BR, B10.HTT, AQR, A.TE, C3H, and CBA; they did not react with cells of strains carrying different Ir regions, i.e., B10.A(4R), B10, B10.M, A.SW, DBA/1. It is therefore concluded that the antigen detected with these antibodies is apparently controlled by the Ir region of the H-2 complex. The antigen is present on some T lymphocytes and absent on B lymphocytes. Its presence or absence seems to correlate with MLC and GVH reactivity.     

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) F₁ 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-2²/H-2^k heterozygote capable of responding well to (T,G)-A--L.     

Genetic control of immune responses in vitro. I. Development of primary and secondary plaque-forming cell responses to the random terpolymer 1-glutamic acid 60-1-alanine30-1-tyrosine10 (GAT) by mouse spleen cells in vitro

In vivo, the antibody response in mice to the random terpolymer L-glutamic acid⁵⁰-L-alanine³⁰-L-tyrosine¹⁰ (GAT) is controlled by a histocompatibility-linked immune response gene(s). We have studied antibody responses by spleen cells from responder and nonresponder mice to GAT and GAT complexed to methylated bovine serum albumin (GAT-MBSA) in vitro. Cells producing antibodies specific for GAT were enumerated in a modified Jerne plaque assay using GAT coupled to sheep erythrocytes as indicator cells. Soluble GAT stimulated development of IgG GAT-specific plaque-forming cell (PFC) responses in cultures of spleen cells from responder mice, C57Bl/6 (H-2^b), F₁ (C57 x SJL) (H-2^b/s), and A/J (H-2^a). Soluble GAT did not stimulate development of GAT-specific PFC responses in cultures of spleen cells from nonresponder mice, SJL (H-2^s), B10.S (H-2^s), and A.SW (H-2^s). GAT-MBSA stimulated development of IgG GAT-specific PFC responses in cultures of spleen cells from both responder and nonresponder strains of mice. These data correlate precisely with data obtained by measuring the in vivo responses of responder and nonresponder strains of mice to GAT and GAT-MBSA by serological techniques. Therefore, this in vitro system can effectively be used as a model to study the cellular events regulated by histocompatibility-linked immune response genes.     

THE EFFECT OF HISTOCOMPATIBILITY-2 TYPE ON RESPONSE TO THE FRIEND LEUKEMIA VIRUS IN MICE

Two types of quantitative response to the F-B strain of Friend virus in segregating generations of a cross involving a susceptible (DBA/2 or BALB/c; H-2²) and a resistant (C57BL/6; H-2^b) mouse strain show a marked correlation with the H-2 type of the mice. Essential susceptibility, as determined by the splenomegalic response to high virus doses, is controlled by a single pair of alleles which segregates independently with respect to the H-2 locus. However, relative susceptibility, as determined by the incidence of the splenomegalic response at moderate or low levels of virus dosage, is significantly greater among mice homozygous or heterozygous for the H-2^d allele than among H-2^b homozygotes in these populations. In addition, the incidence of recovery from splenomegaly induced by a given level of virus dosage is significantly greater in H-2^b homozygotes than in segregants of other H-2 types among their littermates. Possible mechanisms responsible for these effects are discussed.     

GENETIC CONTROL OF THYMUS-DERIVED CELL FUNCTION : I. IN VITRO DNA SYNTHETIC RESPONSE OF NORMAL MOUSE SPLEEN CELLS STIMULATED BY THE MITOGENS CONCANAVALIN A AND PHYTOHEMAGGLUTININ

Concanavalin A- or phytohemagglutinin-stimulated DNA synthetic responses of 1 million normal mouse spleen cells in vitro were significantly different among various inbred strains. BALB/cJ (H-2^d) responded better than C57BL/6J (H-2^b) spleen cells, and the responses of C3H/HeJ or AKR/J (both H-2^k) cells were intermediate. These responses, measured as the increment in thymidine-³H incorporation of mitogen-stimulated compared with unstimulated cultures, varied according to the number of cells cultured or the mitogen concentration. BALB/c spleens had the highest proportion of θ-positive cells, but no direct relationship between the proportion of θ-positive cells and the DNA synthetic response was observed. (BALB/cJ x C57BL/6)F₁ spleen cells responsed as well as BALB/c cells. Responses of spleen cells from (F₁ x C57BL/6) backcross littermates varied over a range equal to, or greater than, that of BALB/c and C57BL/6 cells. There was no correlation between H-2 specificity (H-2^bd or H-2^bb) or sex and the mitogen-stimulated DNA synthetic response of backcross animals. Con A- and PHA-stimulated responses of individual backcross animals were positively correlated with the level of thymidine-⁸H incorporation by unstimulated spleen cells. These results are consistent with autosomal dominant, non-H-2-linked, polygenic control of the mitogen-stimulated in vitro DNA synthetic response of mouse spleen cells.     

GENETICS OF RESTRICTED ANTIBODIES TO STREPTOCOCCAL GROUP POLYSACCHARIDES IN MICE : I. STRAIN DIFFERENCES OF ISOELECTRIC FOCUSING SPECTRA OF GROUP A HYPERIMMUNE ANTISERA

The immune response of nine inbred and one outbred strain of mice to the streptococcal group A polysaccharide was investigated with respect to magnitude and restriction. Analytical isoelectric focusing served as a tool to estimate the degree of restriction of Group A polysaccharide-specific antibodies. It proved feasible to distinguish low and intermediate from high responder strains, and to delineate strain-specificity of isoelectric focusing spectra of the immune sera. For example, immune sera of BALB/c mice, restricted high responders, and of C57BL/6 mice, heterogeneous low responders, had distinct focusing properties. Responsiveness was a dominant autosomal genetic trait in C57BL/6 x BALB/c F₁ hybrid mice, irrespective of the maternal and the paternal genotype; the immune sera of these mice had their own, rather uniform isoelectric focusing spectra whereby structural genes of the low responder strain were expressed to predominant levels in 81% of the hybrids. Responsiveness in C57BL/6 x BALB/c F₂ progeny segregated into 79% high and 21% low responders, and showed no genetic linkage to the following characteristics: hair color, sex, H-2 type, and Ig allotype of the heavy chain. The isoelectric focusing properties of these immune sera indicated segregation into patterns like BALB/c mice (40%), F₁ hybrids (48%), and C57BL/6 mice (12%). Since this segregation is independent of any of the above criteria in these F₂ mice a regulatory gene(s) is postulated that controls the clonal pattern of the immune response.     

The MHC Gene Region of Murine Hosts Influences the Differential Tissue Tropism of Infecting Trypanosoma cruzi Strains

We have previously demonstrated that both parasite genetic variability and host genetic background were important in determining the differential tissue distribution of the Col1.7G2 and JG T. cruzi monoclonal strains after artificial infections in mice. We observed that the JG strain was most prevalent in hearts of mouse lineages with the MHC haplotype H-2^d (BALB/c and DBA2), while Col1.7G2 was predominant in hearts from C57BL/6 mice, which have the H-2^b haplotype. To assess whether the MHC gene region indeed influenced tissue tropism of T. cruzi, we used the same two parasite strains to infect C57BL/6 (H-2^b) and C57BLKS/J (H-2^d) mice; the latter strain results from the introgression of DBA2 MHC region into the C57BL/6 background. We also performed ex vivo infections of cardiac explants from four congenic mice lineages with the H-2^b and H-2^d haplotypes arranged in two different genetic backgrounds: C57BLKS/J (H-2^d) versus C57BL/6 (H-2^b) and BALB/c (H-2^d) versus BALB/B10-H2^b (H-2^b). In agreement with our former observations, Col1.7G2 was predominant in hearts from C57BL/6 mice (H-2^b), but we observed a clear predominance of the JG strain in hearts from C57BLKS/J animals (H-2^d). In the ex vivo experiments Col1.7G2 also prevailed in explants from H-2^b animals while no predominance of any of the strains was observed in H-2^d mice explants, regardless of the genetic background. These observations clearly demonstrate that the MHC region influences the differential tissue distribution pattern of infecting T. cruzi strains, which by its turn may be in a human infection the determinant for the clinical forms of the Chagas disease.     

GENETIC CONTROL OF RESPONSES TO BACTERIAL LIPOPOLYSACCHARIDES IN MICE : I. Evidence for a Single Gene that Influences Mitogenic and Immunogenic Respones to Lipopolysaccharides

In vivo immune responses and in vitro mitogenic responses to bacterial lipopolysaccharides (LPS) have been compared in strains of C3H mice. C3H/HeJ spleen cultures did not support mitogenic responses to LPS and in vivo these mice produce low IgM responses to LPS. On the basis of these two responses, C3H/HeJ mice have been termed low LPS responders. All other strains of C3H mice tested (C3HeB/FeJ, C3H/DiSn, C3H/Str, CWB, CSW, and C3H/Sf and its H-2 congenics) are high LPS responders supporting large in vitro mitogenic and in vivo immune responses to LPS. The immune response difference between low and high LPS responders is a quantitative one. IgM responses are observed in C3H/HeJ mice in the range of 1.0–10 µg LPS. At lower and higher LPS concentrations, immune responses are not observed. In contrast, high LPS responders elicit LPS immune responses over a much wider dose range (0.1–200 µg). The ability to respond well to LPS is dominant as shown by the response of F₁ hybrid mice of low responder and high responder strains. The linkage relationships of mitogenic and immune responsiveness to LPS have been investigated in backcross (C3H/HeJ x CWB)F₁ x CWB mice. All mice that gave in vivo immune responses to LPS also supported mitogenic responses to LPS. The defect in C3H/HeJ mice that limits mitogenic and immune responsiveness to be due to a single autosomal gene which is not linked to the H-2 histocompatibility or heavy-chain allotype loci.     

GENETICS OF A NEW IgVH (T15 IDIOTYPE) MARKER IN THE MOUSE REGULATING NATURAL ANTIBODY TO PHOSPHORYLCHOLINE

The idiotype present on the Fab of a phosphorylcholine-binding IgA myeloma protein TEPC 15 (T15) of BALB/c origin was found in normal serum of BALB/c mice. Molecules carrying the T15 idiotype in normal serum could be adsorbed with Sepharose phosphorylcholine beads and R36A pneumococci. The T15 idiotype is absent in germ-free BALB/c but appears when the mice are conventionalized. A survey of normal sera of inbred strains for the T15 idiotype showed it to be present in BALB/c, 129, C57L, C58, and ST and absent or in low levels in CBA, C3H, C57BL/6, C57BL/Ka, C57BL/10, SJL, B10.D2, DBA/2, RIII, A, AL, AKR, NZB, and NH inbred strains of mice. The T15 idiotype is associated with some but not all strains carrying the IgC_H allotypes found in BALB/c. Linkage of genes controlling the T15 idiotype in normal serum to the IgC_H locus of BALB/c was demonstrated in F₂ progeny of a BALB/c and C57BL cross, Bailey's recombinant inbred strains, C x BD, C x BE, C x BG, C x BH, C x BI, C x BJ, C x BK, and CB20 congenic strains. Among these strains, only those possessing the IgC_H locus of BALB/c including the F₂ progeny consisting of BALB/c homozygotes and BALB/c/C57BL heterozygotes and C x BG and C x BJ recombinants showed the T15 idiotype.     

Cross-priming for a secondary cytotoxic response to minor H antigens with H-2 congenic cells which do not cross-react in the cytotoxic assay

Cytotoxic effector T cells of F1 (BALB/c X BALB.B) (H-2d/b) mice immunized against the minor histocompatibility differences of C57BL/10 (H-2b) can lyse targets from C57BL/10, but cannot lyse B10.D2 (H-2d) targets. Despite this lack of cross-reaction in the cytotoxic assay, C57BL/10 cells do prime F1 (BALB/c X BALB.B) mice for a secondary cytotoxic response to B10.D2. C57BL/10-primed, B10.D2-boosted cytotoxic cells lyse B10.D2 targets but not C57BL/10 targets. DBA/2 (H-2d) spleen cells or thymocytes prime F1 mice for a secondary response to DBA/2, B10.D2, and C57BL/10 cells, but DBA/2 mastocytes, P815, do not prime for a response to C57BL/10. Whether H-2 congenic lymphoid cells express minor histocompatibility determinants which cross-react at the cytotoxic T-cell level or the helper T-cell level is discussed.     

Contribution of different cell types to the genetic control of immune responses as a function of the chemical nature of the polymeric side chains (poly-L-prolyl and poly-DL-alanyl) of synthetic immunogens

Genetic regulation of immunological responsiveness was studied at the cellular level by comparing the limiting dilutions of immunocompetent cells from spleen, thymus, and bone marrow of high and low responders as a function of the poly-L-prolyl and poly-DL-alanyl side chains of two synthetic polypeptide immunogens. The spleens of immunized and unimmunized high responder DBA/1 mice were found to contain respectively, 18- and 7-fold more limiting precursor cells specific for (Phe, G)-A--L than the spleens of SJL low responder donors. These results, using a synthetic polypeptide built on multichain poly-DL-alanine, confirm the findings reported for polypeptides built on multichain poly-L-proline (1, 2), that there is a direct correlation between immune response potential and the relative number of immunocompetent precursors stimulated. Cell cooperation between thymocytes and bone marrow cells was demonstrated for both (T, G)-Pro--L and (Phe, G)-A--L. Limiting dilutions of thymus and bone marrow cells in the presence of an excess amount of the complementary cell type indicated an eightfold lower number of detected (T, G)-Pro--L-specific precursors in DBA/1 (low responder) marrow when compared with SJL (high responder) marrow. No differences were observed in the frequency of relevant high and low responder thymocytes for the (T, G)-Pro--L immunogen. These results are similar to those reported for the (Phe, G)-Pro--L (3). In contrast to the cellular studies reported for the Pro--L series of immunogens, the marrow and thymus cell dilution experiments for (Phe, G)-A--L revealed genetically associated differences in both the marrow and thymus populations of immunocytes from high (DBA/1) and low (SJL) responders. In addition to a fivefold difference in limiting marrow cell precursors (similar to that seen in the Pro--L studies), a striking difference was observed between the helper cell activity of high responder DBA/1 and low responder SJL thymocytes. This difference was indicated by the observation that low responder thymocyte dilutions followed the predictions of the Poisson model, whereas dilutions of high responder thymocytes did not conform to Poisson statistics. Transfers of allogeneic thymus and marrow cell mixtures from DBA/1 and SJL donors confirmed the syngeneic dilution studies showing that the genetic defect of immune responsiveness to (Phe, G)-A--L is expressed at both the thymus and marrow immunocompetent cell level. The parameters presently known for genetic control of immune responses specific for (Phe, G) (Ir-1 gene) and for Pro--L (Ir-3 gene) have been compared. The Ir-1 and Ir-3 genes are not only distinct by genetic linkage tests (to H-2) (5, 6, 9), but they are also seen to be different by cellular studies. Furthermore, expression of low responsiveness within a given cell population was shown to depend on the chemical structure of the whole immunogenic macromolecule.     

COMPARATIVE ANALYSIS OF ANTIGEN-BINDING T CELLS IN GENETIC HIGH AND LOW RESPONDER MICE

[¹²⁵I](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, [¹²⁵I]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.     

RAPID VIRAL INDUCTION OF MURINE LYMPHOMAS IN THE GRAFT-VERSUS-HOST REACTION

When weanling (SJL/J x C57BL/1)F₁ hybrid mice were given five weekly-injections of small doses of viable SJL/J spleen cells, so as to induce a graft-versus-host reaction (GVHR), reticulum cell sarcomas were induced in all of the host mice by the 40th day after the first cell injection. Such tumors, on transplantation, were accepted by syngeneic (SJL/J x C57BL/1)F₁ and C57BL/1 hosts, but not by SJL/J or NZB mice. Cell-free extracts of SJL/J spleens injected into similar hybrids resulted in identical tumors in all hosts within the same period; the transplantation characteristics were also similar. Normal (SJL/J x C57BL/1)F₁ hybrids as well as similar hybrids injected with SJL/J liver or syngeneic F₁ spleen cells did not develop tumors. Cell-free preparations of eight tumors induced in F₁'s by viable SLJ/J spleen cells were injected into newborn (C57BL/1 x A)F₁ and C57BL/1 mice: tumors were induced, with seven of eight tumor preparations, with a latent period of 33–49 days. Such tumors were lymphosarcomas, and, in the case of (C57BL/1 x A)F₁ hosts, further transplantation revealed that they were antigenically C57BL/1 tumors. These experiments provide conclusive evidence for a viral etiology of GVHR-induced tumors. Furthermore, tumor induction in the GVHR does not appear to depend specifically on an immunological mechanism but is most probably due to release or activation of a sufficient quantity of oncogenic virus within a certain time period in a highly susceptible host. Comparison with radiation induction of viral leukemia in mice revealed similarities in regard to optimal host age and the spacing of administration of the tumor-inducing agent. SJL/J mice carry a type C virus which causes a high incidence of spontaneous Hodgkin-like tumors by 1 yr of age; C57BL/1 mice do not develop lymphomas spontaneously but carry a latent leukemogenic virus. Their hybrid also has a low incidence of spontaneous lymphomas. Based on the results of these and previous experiments, the viruses of these strains of mice appear to be highly synergistic in tumor induction in the GVHR. The SJL/J virus is a powerful oncogenic agent. The C57BL/1 virus may be a helper virus to the SJL/J, but is a more powerful determinant of the antigenic composition of the induced tumors. This suggests that the virus of C57BL/1 mice, when activated, is capable of controlling the C57BL/1 genome. Because of the ease and rapidity of viral tumor induction, the SJL/J and C57BL/1 strains of mice, with their F₁ hybrid, should be useful for further study of the mechanisms controlling induction of such tumors.     

GENETIC CONTROL OF IMMUNE RESPONSES IN VITRO : III. TOLEROGENIC PROPERTIES OF THE TERPOLYMERL-GLUTAMIC ACID60-L-ALANINE30-L-TYROSINE10 (GAT) FOR SPLEEN CELLS FROM NONRESPONDER (H-2qANDH-2s) MICE

Although nonresponder, H-2^s and H-2^q, mice fail to develop GAT-specific PFC responses to GAT, they do develop GAT-specific PFC responses when stimulated by GAT complexed to an immunogenic carrier such as methylated bovine serum albumin. The studies described in this paper show that injection of nonresponder mice with GAT specifically decreases their ability to develop anti-GAT PFC responses to a subsequent challenge with GAT-MBSA. Addition of GAT to cultures of spleen cells from nonresponder mice also prevents development of the GAT-specific PFC responses stimulated by GAT-MBSA. Thus, interaction of nonresponder spleen cells with GAT leads to the induction of unresponsiveness in vivo and in vitro. Various parameters of the tolerance induction have been investigated and described. A comparison of the effects of GAT on B cells indicates that nonresponder B cells are more readily rendered unresponsive by soluble GAT than are responder B cells. The significance of these data for our understanding of Ir gene regulation of the immune response is discussed.     

Genetic control of the immune response to staphylococcal nuclease. III. Time-course and correlation between the response to native nuclease and the response to its polypeptide fragments

The progression of the Ir gene-controlled antibody response to staphylococcal nuclease in mice with repeated immunizations has been examined. H-2-linked control of the response to a single immunization with 100 mug of nuclease in complete Freund's adjuvant was confirmed. However, among strains of the high responder H-2a haplotype, the response of the A/J mice was about 10-fold higher than that of the B10.A, indicating additional non-H-2-linked control. In addition, the low responder C57BL/10 (H-2b) strain produced antibody levels as high as or higher than those of the congenic high responder B10.A (H-2a) strain when both strains were repeatedly immunized, indicating complexity even in the H-2-linked control of the response to this small monomeric protein. Polypeptide fragments of nuclease were also studied as immunogens. The antibody response to one fragment (residues 99-149) was found to follow the same pattern among five strains tested as that to whole nuclease. However, in this case the C57BL/10 was found to be a nonresponder rather than a low responder, failing to develop a response despite repeated immunizations. In contrast, the C57BL/10 showed a low but significant response to another fragment (residues 1-126) of nuclease. These results suggest that the apparent H-2-linked control of the response to whole nuclease is a reflection of the ability to recognize a determinant(s) in the region from residues 99 to 149, and that the eventual response of the C57BL/10 strain after hyperimmunization reflects the recognition of other determinants. If these observations reflect the common recognition of a determinant on native nuclease and on a random-conformation fragment, they have implications about the conformational specificity of the receptors, or the flexibility of the determinants, involved in H-2-linked Ir-gene control. In addition, evidence is presented for a possible second H-2- linked gene (or genes) controlling the response to other determinants of nuclease expressed on the polypeptide fragments.