Regulation of immune responses by I-J gene products. I. Production and characterization of anti-I-J monoclonal antibodies.

Using a novel, two-step functional screening procedure, we have isolated hybridoma B cell lines secreting monoclonal antibodies directed against gene products of the I-Jb and I-Jk subregions of the mouse H-2 complex. These monoclonal antibodies act in vitro by allowing nonresponder spleen cells to respond to normally suppressive quantities of poly(Glu50Tyr50) (GT) (WF8 series of anti-I-Jk monoclonal antibodies) or to suboptimal concentration of poly(Glu60Ala30Tyr10) (WF9 series of anti-I-Jb monoclonal antibodies). Some of the culture supernates that show augmenting activity bind GT-specific T cell-derived suppressor factor (GT-TsF), indicating that some monoclonal antiantibodies display a nonspecific enhancing effect, or, more likely, that anti-I-J monoclonal antibodies have been produced against I-J determinants not found on TsF. It is this last possibility that is most intriguing and that might serve as a means for exploring the heterogeneity of the I-J subregion. It is also possible that some of our monoclonal anti-I-J antibodies might detect antigenic determinants selectively expressed on suppressor T cells, helper T cells, and/or macrophages. In addition, we have demonstrated that monoclonal anti-I-J antibodies should be useful in the biochemical characterization and purification of a monoclonal GT-TsF. These haplotype-specific anti-I-J monoclonal antibodies should prove to be powerful tools for future studies exploring the role of I-J gene products in the regulation of specific immune responses.

Regulation of immune responses by I-J gene products. VI. Recognition of I-E molecules by I-J-bearing suppressor factors.

Poly(Glu50Tyr50) (GT) is not immunogenic in most inbred mouse strains. GT injection produces an I-J--bearing, GT-specific T-cell--derived suppressor factor (GT-TsF1) in H-2b,d,k haplotype mice. GT-TsF1 generates second-order suppressor T cells (Ts2) in H-2a,d,k haplotype mice. Here, we show that in order for GT-TsF1 to act, the recipient strain must express I-E molecules. This suggests that T cells are not the primary target of GT-TsF1. GT-TsF1 can be presented by Ia+ A20-2J B lymphoma cells. GT-TsF1 presentation is blocked by anti-I-E, but not by anti--I-A, mAb, whereas GAT presentation is blocked by anti-I-A, but not by anti--I-E, mAbs. These data suggest that I-J recognizes (or is recognized by) I-E. The existence and role of I-J molecules in immune regulation are discussed in light of these data.

Genetic control of specific immune suppression. III. Mapping of H-2 complex complementing genes controlling immune suppression by the random copolymer L-glutamic acid50-L-tyrosine50 (GT).

Earlier studies from our laboratory demonstrated that the terpolymer of L-glutamic acid, L-alanine, and L-tyrpsine (GAT) stimulated the development of T cells capable of specifically suppressing the antibody responses in vivo and in vitro of nonresponder strains (bearing the H-2(s), H-2(q), and H-2(p) haplotypes) to GAT complexed with an immunogenic carrier, methylated bovine serum albumin, MBSA (1,2). We then extended these findings to another antigen, the copolymer of L-glutamic acid and L-tyrosine (GT). None of 19 inbred or congenic resistant mouse strains developed antibody responses to GT after immunization with this synthetic polypeptide in adjuvants. All the strains investigated, however, developed IgG plaque-forming cells (PFC) primary responses to GT complexed with MBSA (3). This permitted us to determine that: (a) preimmunization with GT suppressed the response to GT-MBSA in certain but not in all strains; (b) the suppression could be transferred by thymocytes and spleen cells from GT-primed animals; (c) the development of GT-specific suppressor cells is under dominant control of H-2- linked gene(s) which have been designated specific immune suppressor genes (Is genes); (d) the Is genes are antigen specific since GAT-MBSA responses are suppressed by GAT in strains carrying the H-2(q) haplotype, while GT-MBSA responses are not suppressed by the related polymer GT in these same strains (3,4). The experiments reported in this study map the Is genes responsible for GT-specific suppression within the H-2 complex. The data indicate that the K and D loci are not concerned with GT-specific suppression, and that this phenomenon is controlled by complementing or interacting genes which map on either side of cross-over events between the IB and IC subregions.

Restriction of primary responses to the IgG class and dependency of IgM responses on secondary immunization for the copolymers of L-glutamic acid, L-tyrosine, and L-alanine.

Primary responses to the linear polymers of L-glutamic acid, L-tyrosine, and L-alanine are restricted to the IgG class of antibodies. The appearance of specific IgM antibodies against these antigens is dependent upon secondary immunization, in contrast to many classical antigenic systems. The presence of an IgM response was verified by a direct plaque-forming cell assay, the inhibition of direct plaques by an antiserum specific for mouse micron-chain, and the physical separation of IgM and IgG GAT-specific antibodies by gel filtration. Preimmunization of the appropriate nonresponder strain with GAT or GT inhibits both the secondary IgM and IgG responses to GAT-MBSA and GT-MBSA, respectively. The tolerance observed is due to the induction of suppressor cells as demonstrated by cell transfer experiments.

Effect of colchicine on the antibody response. II. Demonstration of the inactivation of suppressor cell activities by colchicine.

The simultaneous administration of colchicine (CC) with a T-independent antigen, e.g. 2,4,6-trinitrophenyl-keyhold limpet hemocyanin-Sepharose, to intact animals effectively enhanced their hapten-specific plaque-forming cell (PFC) response. However, in congenitally athymic nude mice in which T-cell regulation was absent, CC was ineffective in producing enhancement. These observations suggest that the target cell acted upon by CC is most likely thymus-derived. Furthermore, the injection of CC with the co-polymer of L-glutamic acid50-L-tyrosine50 (GT) abolished GT-specific suppression of the PFC response to GT-methylated bovine serum albumin. Spleen cells from CC-treated and GT-primed hosts could no longer transfer suppressive activity to normal recipients. These results provide evidence that CC is capable of inactivating or eliminating suppressor cells or their precursors. Thus, CC-induced enhancement of the antibody response may be explained, at least in part, by its antimitotic, and hence lethal effect on dividing suppressor T cells.

Regulation of immune responses by I-J gene products. II. Presence of Both I-Jb and I-Jk suppressor factors in (nonsuppressor x nonsuppressor) F1 mice.

Antigen-specific suppression to poly(Glu50-Tyr50) (GT) is under the control of two complementary immune suppressor (Is) genes located in the major histocompatibility (H-2) complex of the mouse. Suppressor strains of mice produce both suppressor T (Ts) cells and Ts-derived suppressor factors (TsF) that bear antigenic determinants of the I-J subregion of the H-2 complex. Nonsuppressor strains of mice, on the other hand, are not suppressed by GT preimmunization. These nonsuppressor mice, however, can be classified according to those that lack the ability to make GT-specific T cell-derived suppressor factor (GT-TsF) after GT injection (i.e., H-2a, I-Jk mice) and those that lack the ability to be suppressed by the appropriate GT-TsF (i.e., H-2b,g2, I-Jb mice). In the present study, we demonstrate that (H-2a x H-2b,g2)F1 hybrid mice produce distinct GT-specific suppressor factors of both parental I-J haplotypes. Moreover, only the I-Jb-bearing GT-TsF derived from these F1 hybrid mice is able to induce second-order suppressor cells (Ts2). This is consistent with the observation that injection of GT-TsF1 derived from C57BL/6 (I-Jb) mice into A/J (I-Jk) mice leads to the production of an antigen-specific I-Jk GT-TsF2. Our results suggest that Is gene complementation occurs through a different cellular mechanism that was previously observed for Ir gene complementation. Further, we show that complementing (non-suppressor X nonsuppressor)F1 hybrid mice produce an I-Jb (and not an I-Jk) GT-TsF1 and an I-Jk (not an I-Jb) GT-TsF2, thus suggesting a heterogeneity of Ia loci within the I-J subregion. Data presented in the present study suggest that there may be even more heterogeneity within the I-J subregion than has has been heretofore reported with regard to I-J expression on Ts.

Antigen-specific T cell-mediated suppression. V. H-2-linked genetic control of distinct antigen-specific defects in the production and activity of L-glutamic acid50-L-tyrosine50 suppressor factor.

The occurrence of distinct genetic defects affecting the generation of T cell-derived suppressor factor (TsF) or the suppressive activity of such TsF was investigated. For the synthetic polypeptide L-glutamic acid50-L-tyrosine50 (GT), it could be shown that the nonsuppressor strain A/J fails to produce suppressor T cells (Ts1) capable of GT-TsF generation upon challenge with GT. Conversely, B6, another nonsuppressor strain, produces GT-TsF active on other allogeneic strains such as A/J, but itself fails to be suppressed by this material. (B6A)F1 mice both make GT-TsF, and are suppressed by it. Further experiments revealed that the production of GT-TsF and the ability to be suppressed by GT-TsF are under the control of H-2-linked genes. Finally, the defect in GT-TsF activity in B6 mice was shown to be exquisitely antigen specific, in that this strain can be suppressed by a closely related TsF specific for L-glutamic acid60-L-alanine30-L-tyrosine10. It is suggested that H-2 (I) control of suppressor T cell (Ts) activity may reflect the involvement of I-A and I-C gene products in antigen presentation to Ts in analog with other T cell subsets, and that TsF function might also involve such presentation, in this case of the idiotypic structures of the TsF-combining site. Predictions deriving from this hypothesis are discussed, including the possibility that H-2 linked immune response genes regulate auto-anti-idiotypic responses in immune networks.

Immunosuppressive factor(s) specific for L-glutamic acid50-L-tyrosine50 (GT) II. Presence of I-J determinants on the GT-suppressive factor.

The responses to the synthetic antigens, L-glutamic acid(60)-L- alanine(30)-L-tyrosine(10) (GAT) and L-glutamic acid(50)-L-tyrosine(50) (GT) are controlled by genes in the I region of the mouse H-2 complex (1-3). Preimmunization of the mice bearing the H-2(p,q,s) nonresponder haplotypes with GAT stimulates the development of suppressor T cells that inhibit in vivo or in vitro antibody responses to GAT complexed to the immunogenic carrier, methylated bovine serum albumin (GAT-MBSA) (4). The copolymer GT is not immunogenic in any inbred mouse strain tested, and has a suppressive effect on the antibody responses to GT-MBSA in mouse strains bearing the H-2(d,f,k,s) haplotypes; suppressor T cells have been demonstrated to be responsible for specific GT suppression (3). We have obtained specific suppressive extracts from thymus and spleen cells of GAT-or GT-primed suppressor strains (5,6). The specific suppressive T-cell factors in the active extracts have been characterized (6,7) and appear similar to the carrier-specific suppressor factor described by Tada and Taniguchi (8). These products belong to a family of newly identified molecules coded for by the I region of the H-2 complex with affinity for antigen and helper (9,10) or suppressive (5-8) regulatory activity on the immune response. Recently, Tada et al. have reported that the keyhole limpet hemocyanin (KLH)-specific suppressor factor is coded for by the I-J subregion of the H-2 complex (11). We now demonstrate also that a GT-specific suppressor factor extracted from the spleens and thymuses of B10.BR (H-2(k)) mice bears determinants controlled by the I-J subregion of the H-2 complex.

Immunosuppressive factor(s) specific for L-glutamic acid50-L-tyrosine50 (GT). III. Generation of suppressor T cells by a suppressive extract derived from GT-primed lymphoid cells.

Injection of mice with L-glutamic acid50-L-tyrosine50 (GT)- or L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT)-specific suppressor T-cell factor (GT-TsF or GAT-TsF) up to 5 wk before antigenic challenge challenge suppresses GT-methylated bovine serum albumin (MBSA) and GAT-MBSA plaque-forming cells responses. T suppressor cells are responsible for the suppression induced by the suppressive extract as demonstrated by adoptive transfer and sensitivity to anti-Thy-1 and complement treatment. We conclude that suppressive extract induces specific suppressor T cells. The material responsible for generation of suppressor T cells is a product of the I subregion of the H-2 complex. We have excluded that suppressive quantities of antigens are present in the extract. A/J mice, which can neither be suppressed by GT nor make GT-TsF can be suppressed by BALB/c GT-tsf. Spleen cells from BALB/c GT TsF-primed A/J mice can adoptively transfer suppression to normal syngeneic recipients. A/J mice appear to be genetically defective in cells involved in factor production. These results are discussed in the light of a two-step model for induction of antigen-specific suppressor cells.

Genetic control of specific immune suppression. IV. Responsiveness to the random copolymer L-glutamic acid50-L-tyrosine50 induced in BALB/c mice by cyclophosphamide.

Previous reports from our laboratory have demonstrated the stimulation of specific suppressor T cells in genetic nonresponder mice after immunization with the terpolymer of L- glutamic acid, L-alanine, and L-tyrosine (GAT) (1,2) and with the copolymer of L-glutamic acid and L-tyrosine (GT) (3-5). These findings raise two important questions: (a) do the specific suppressor T cells inhibit an antibody response which would otherwise develop in nonresponder mice; and, (b) can specific helper T cells inhibit an antibody response which would otherwise develop in nonresponder mice; and, (b) can specific helper T-cell activity be detected in these animals. Responsiveness appears to be completely dominant over suppression in (responder x suppressor)F(1) hybrids, therefore, we have been unable to detect suppressor cells in these hybrids after conventional immunization with GAT (2). However , using special conditions of antigen administration, GAT helper activity could be demonstrated in nonresponder DBA/1 ("suppressor") mice. Thus, GAT-specific helper activity was not detected in these nonresponder animals after immunization with GAT irrespective of the adjuvant used, but could be stimulated by macrophage-bound GAT or by GAT complexed with methylated bovine serum albumin GAT-MBSA (6). In the current report we have taken advantage of the fact that suppressor T-cell activity is more sensitive to cyclophosphamide treatment than T-cell helper activity (7) to demonstrate the presence of GT-specific helper activity in "nonresponder" BALB/c mice. We describe: (a) the dose of cyclophosphamide and conditions of treatment which inhibits the well-documented stimulation of specific suppressor T cells in BALB/c mice injected with GT previous to immunization with GT-MBSA, and (b) the ability of cyclophosphamide to permit the development of primary PFC responses to GT in these "nonresponder" mice. These cyclophosphamide-induced responses are not characterized by the high levels of antibody detected in genetic responder animals.

Gain/loss of poly(Glu50Tyr50)/poly(Glu60Ala30Tyr10) responsiveness in the bm12 mutant strain.

The development of inbred strains of mutant mice has proven useful in ascribing specific gene functions to particular genetic loci within the regions and subregions of the H-2 complex. The B6.C-H-2bm12 (bm12) strain is of particular interest in that, compared to parental C57Bl/6Kh (B6) mice, it bears a presumptive single gene mutation altering the Ab beta chain encoded by the I-A subregion. Our data show that bm12 mice have gained the ability to respond to poly(Glu50Tyr50)(GT) and have lost the ability to make plaque-forming cell or delayed-type hypersensitivity responses to the closely related copolymer, poly(Glu60Ala30Tyr10)(GAT), although retaining the ability to mount a GAT-specific T cell proliferative response. This is in sharp contrast to the parental B6 strain, which is a GT nonresponder and a GAT responder. Thus, this study is the first to report the establishment of responder status as a consequence of mutation. Possible mechanisms accounting for the gain/loss of GT/GAT responsiveness in the context of a two-step helper T cell model are discussed.

The role of I-J and Igh determinants on F1-derived suppressor factor in controlling restriction specificity.

In the 4-hydroxy-3-nitrophenyl acetyl (NP) contact sensitivity system, the activity of third-order suppressor cells and their factors is restricted by H-2(I-J) and Igh linked genes. The present report analyzes the specificity of NP-specific Ts3 cells and factors derived from H-2 and Igh heterozygous (B6 X C3H)F1 mice. Two approaches were used. First, heterogeneous populations of F1 Ts3 cells were activated in vitro and then assayed in Ts3-depleted recipients which carried different combinations of H-2 and Igh alleles. The second approach was to hybridize the Ts3 cells and analyze the specificity of the F1-derived TsF3. The combined data demonstrated four functionally distinct populations of Ts3 cells. The activity of each population was restricted by a particular combination of H-2 and Igh haplotypes. Thus, Ts3 cells derived from F1 donors can demonstrate an apparent scrambling of H-2 and Igh restriction specificities. There was functional allelic exclusion of the H-2(I-J) and Igh determinants expressed on (B6 X C3H)F1 hybridoma-derived TsF3. Thus, TsF3 from each cloned hybridoma line expressed only one set of I-J and Igh determinants. Furthermore, there was a complete correlation between the I-J and Igh linked determinants expressed on TsF3 and the restriction specificity. In view of the recent findings on the molecular biology of the I-J region, an alternative interpretation of the role of I-J determinants on suppressor cells and factors is offered.

Inhibition of angiogenesis by interleukin 4.

Interleukin (IL)-4, a crucial modulator of the immune system and an active antitumor agent, is also a potent inhibitor of angiogenesis. When incorporated at concentrations of 10 ng/ml or more into pellets implanted into the rat cornea or when delivered systemically to the mouse by intraperitoneal injection, IL-4 blocked the induction of corneal neovascularization by basic fibroblast growth factor. IL-4 as well as IL-13 inhibited the migration of cultured bovine or human microvascular cells, showing unusual dose-response curves that were sharply stimulatory at a concentration of 0.01 ng/ml but inhibitory over a wide range of higher concentrations. Recombinant cytokine from mouse and from human worked equally well in vitro on bovine and human endothelial cells and in vivo in the rat, showing no species specificity. IL-4 was secreted at inhibitory levels by activated murine T helper (TH0) cells and by a line of carcinoma cells whose tumorigenicity is known to be inhibited by IL-4. Its ability to cause media conditioned by these cells to be antiangiogenic suggested that the antiangiogenic activity of IL-4 may play a role in normal physiology and contribute significantly to its demonstrated antitumor activity.

Immunologic inhibition of ultraviolet radiation-induced tumor suppressor cell activity.

Long-term exposure of C3H mice to ultraviolet radiation resulted in the formation of suppressor T cells that recognize ultraviolet radiation-induced regressor skin cancers as a class before the appearance of overt tumors. Administration of monoclonal antibodies to the product of the I-Jk subregion of the major histocompatibility complex or low doses of cyclophosphamide in vivo inhibited the development or activity of these cells. This activity of the monoclonal antibody was eliminated by adsorption on B10.BR (I-Jk) but not B10.D2 (I-Jd) splenocytes. These findings provide evidence that elements expressing the I-J determinant are important in regulating the host response prior to the overt development of ultraviolet radiation-induced skin cancers and suggest novel therapeutic approaches to malignancies or other diseases involving suppressor T cells in their pathogenesis.

Effects of long-term treatment of mice with anti-I-J monoclonal antibody and dialyzable leukocyte extract on immune function and lifespan.

In 1969 Walford hypothesized that age-related dysfunctions of the immune system may be involved in the pathogenesis of the lesions and disease of aging. Studies were initiated to test whether immunologic interventions intended to maintain the integrity of the immune system would delay the onset of diseases of aging and prolong lifespan. Adult BC3F1 mice were treated with anti-I-J monoclonal antibody, with human dialyzable leukocyte extract, or with saline once a week for one year. Spleen cells from the mice were then assayed for suppressor, T-helper and B-cell activity. Treatment with dialyzable leukocyte extract decreased the elevated nonspecific suppressor activity. Mice treated with anti-I-J antibody had elevated T-helper cell activity. In another experiment, mice were treated weekly with anti-I-J antibody, dialyzable leukocyte extract, or saline from 18 months of age until natural death. The mice were immunized with avian gammaglobulin at 27 and again at 29 months of age. Both types of immunologic intervention resulted in a greater secondary antibody response than that of the saline-treated control mice. Mice treated with anti-I-J antibody survived longer than did mice of the other two groups. There was a correlation between the magnitude of the secondary response of individual mice and their lifespan. The results provide support for the immunologic theory of aging.

Bacteria as solid phase in a concentration fluorescence immunoassay analysis of antibodies to surface antigens.

A modified solid-phase fluorescence immunoassay was developed using bacterial cells as the solid phase to screen antibodies produced against surface antigens from a clinical isolate of Escherichia coli, strain 1-149. The bacterial solid phase was used to analyze both polyclonal and monoclonal antibodies. The bacterial concentration fluorescence immunoassay (BCFIA) showed up to 50-fold greater sensitivity in bacterial cell detection as compared to ELISA (enzyme-linked immunosorbent assay). Moreover, BCFIA was considerably faster than ELISA with uniform reproducibility. This paper demonstrates the utility of using bacteria and their surface antigens as solid-phase matrices for antibody characterization in a FIA.

A rapid method for quantitation of antiviral antibodies.

This paper examines the parameters necessary for the efficient measurement of anti-Theiler's murine encephalomyelitis virus (TMEV) antibodies in an affinity-dependent manner using a variation of a solid-phase particle concentration fluorescence immunoassay (PCFIA). By allowing antibody to react with fluorochrome-labelled virus in fluid phase and subsequently capturing the resulting virus-antibody complexes with anti-immunoglobulin coated polystyrene particles (fluid-phase PCFIA), the present assay allows for both greater sensitivity, specificity and preservation of conformational viral epitopes than do solid-phase immunoassays. Fluid-phase PCFIA proved to be a more rapid quantitative assay than ELISA and significantly diminished non-specific binding by both untreated and heat-inactivated normal mouse sera. This methodology also allowed us to perform competition assays and to determine the dissociation kinetics of anti-viral antibody preparations, investigations which cannot generally be performed as solid-phase immunoassays. Thus fluid-phase PCFIA is a rapid and efficient immunoassay with excellent reproducibility and great versatility.

Class II-restricted T cell responses in Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease. III. Failure of neuroantigen-specific immune tolerance to affect the clinical course of demyelination.

Intracerebral inoculation of Theiler's murine encephalomyelitis virus (TMEV) into susceptible mouse strains produces a chronic demyelinating disease in which mononuclear cell-rich infiltrates in the central nervous system (CNS) are prominent. Current evidence strongly supports an immune-mediated basis for myelin breakdown, with an effector role proposed for TMEV-specific, major histocompatibility complex (MHC) class II-restricted delayed-type hypersensitivity (DTH) responses in which lymphokine-activated macrophages mediate bystander demyelination. The present study examined the possibility that concomitant or later-appearing neuroantigen-specific autoimmune T cell responses, such as those demonstrated in chronic-relapsing experimental allergic encephalomyelitis (R-EAE), may contribute to the demyelinating process following TMEV infection. T cell responses against intact, purified major myelin proteins (myelin basic protein (MBP) and proteolipid protein (PLP], and against altered myelin constituents were readily demonstrable in SJL/J mice with R-EAE, but were not detectable in SJL/J mice with TMEV-induced demyelinating disease. TMEV-infected mice also did not display T cell responses against the peptide fragments of MBP(91-104) and PLP(139-151) recently shown to be encephalitogenic in SJL/J mice. In addition, induction of neuroantigen-specific tolerance to a heterogeneous mixture of CNS antigens, via the i.v. injection of syngeneic SJL/J splenocytes covalently coupled with mouse spinal cord homogenate, resulted in significant suppression of clinical and histologic signs of R-EAE and the accompanying MBP- and PLP-specific DTH responses. In contrast, neuroantigen-specific tolerance failed to alter the development of clinical and histologic signs of TMEV-induced demyelinating disease or the accompanying virus-specific DTH and humoral immune responses. These findings demonstrate that TMEV-induced demyelinating disease can occur in the apparent absence of neuroantigen-specific autoimmune responses. The relationship of the present results to the immunopathology of multiple sclerosis is discussed.

Antibody production in organ culture by bursae of mature chickens and the development of immunological compentence.

Antibody responsiveness of bursal lymphocytes was studied in vitro. Organ culture of bursal tissue in the presence of antigen, either sheep erythrocytes or bovine serum albumin, results in significant numbers of plaque-forming cells (PFC) compared to controls. The response in organ culture is age-dependent in that only bursae from chickens at least three weeks of age contained significantly increased numbers of secreting cells. Prolonged culture of normally unresponsive bursae from newly hatched birds results in a PFC response to antigen, suggesting that in vitro maturation occurs.

Cell-mediated immune responses to poliovirus II. Survey of delayed hypersensitivity and T-cell proliferative responses in inbred mouse strains.

Some epidemiological reports suggest a human genetic predisposition for susceptibility to the development of paralytic poliomyelitis. In a previous study of cell-mediated immune responses by mice to poliovirus (PV), we showed differences in the responses by BALB/c and C57BL/6 (B6) mice. The present study is a further analysis of the delayed hypersensitivity (DTH) and T cell proliferative (Tprlf) responses to PV in 17 different inbred strains of mice, to determine if these responses were under major histocompatibility complex (MHC) or other genetic control. Both DTH and Tprlf to PV did not correlate with MHC for responses to any of the three PV serotypes. Further, we found a lack of concordance of DTH and Tprlf responses to a given PV serotype. The cell-mediated immune responses by any one mouse strain to one PV serotype is not predictive of that mouse strain's response to another PV serotype.