Autoantibodies specific for the cardiac myosin isoform are found in mice susceptible to Coxsackievirus B3-induced myocarditis

Several mouse strains are susceptible to immunopathic myocarditis after infection with Coxsackievirus B3 (CB3). This disease is associated with autoantibodies that are directed against myosin. In this study we characterized sera from CB3-infected mice for their reactivity with three different myosin isoforms (heart, skeletal muscle, and brain myosins) and for autoantibody isotype by using an ELISA. Competitive inhibition assays and absorption studies with various myosins demonstrated the presence of two autoantibody populations in sera of susceptible A.CA and A.SW mice. The first was specific for cardiac myosin and was mainly IgG. The second antibody population cross-reacted with heart, skeletal muscle, and brain myosin and was mainly IgM. B10.PL/SgSf and B10.A/SgSf mice, which do not develop immunopathic myocarditis, produced only the IgM autoantibody population cross-reactive with all three myosin isoforms. Because the heart-specific myosin autoantibodies were found exclusively in the mouse strains that developed immunopathic myocarditis, they can be considered a serologic marker for autoimmune heart disease.     

Major histocompatibility complex-linked control of the murine immune response to myelin basic protein

Recent experiments have shown that different regions of myelin basic protein (MBP) are encephalitogenic for different inbred strains of mice. It was therefore of interest to determine whether the immune response to MBP was MHC associated, and if so, what subregion controlled this response. Because PL/J and A/J mice were good responders to mouse MBP and C57Bl/10SN were not, B10.PL(73NS) and B10.A mice were immunized with mouse MBP under conditions designed to induce EAE. These strains were found to be highly susceptible. Intra-H-2 recombinant mice were then assessed for susceptibility. B10.A(4R) and B10.MBR were susceptible, whereas B10.A(5R) were resistant. Thus, EAE induced by purified MBP is under the control of the MHC, and the response maps to the I-A subregion. Production of IL 2 in vitro by T cells from MBP-primed mice in the presence of antigen and adherent cells was blocked by monoclonal antibody to the I-A, but not the I-E, subregion. When the specificity of the encephalitogenic response was tested, peptide 1-37 was active in B10.PL(73NS) and B10.A mice, whereas peptide 89-169 was active in A.SW, SWR, and B10.T(6R) strains. Serum from mice immunized with MBP peptides was assayed for antibody content. PL, B10.PL, and B10.A mice made a good antibody response to peptides 1-37 and 43-88 but were nonresponsive to peptide 89-169. SJL, A.SW, SWR, and B10.T(6R) mice responded well to peptide 89-169 but were poorly responsive to peptides 1-37 and 43-88.     

Prevention of myosin-induced autoimmune myocarditis in mice by anti-L3T4 monoclonal antibody

This study was aimed at studying the effect of the induction of immune tolerance to swine cardiac myosin from anti-L3T4 monoclonal antibody injection and whether the immune tolerance could protect mice with myosin-induced myocarditis from myocardial injury. Twenty-four Balb/c mice were divided into two groups at random. All of the mice were immunized with swine cardiac myosin on the 1st day, 14th, 28th, 42nd, and 52nd day. Immune tolerance was induced by triplicate injections of 400 microg anti-L3T4 McAb on the 0 day (intravenous), 1st day, and 2nd day (intraperitoneal) in McAb-treated group. In the saline-treated group, saline of the same volume as anti-L3T4 monoclonal antibody was used as a control. The sera and hearts biopsies of all mice were collected on the 58th day. The anti-cardiac myosin antibody was examined with ELISA, and pathological changes of heart were observed by light microscope. It was shown that mice immunized with swine cardiac myosin could produce anti-myosin antibody and the anti-cardiac myosin antibody was positive in most of the saline-treated group but negative in the McAb-treated group. Morphologically, myocardial degeneration, necrosis, and infiltration of inflammatory cells were found in the saline-treated group but not in the McAb-treated group. In conclusion, this study indicated that the immune tolerance to cardiac myosin was induced by the anti-L3T4 monoclonal antibody, and accordingly myocardial injury could be prevented by induction of immune tolerance.     

LPS promotes CB3-induced myocarditis in resistant B10.A mice.

Coxsackie virus B3 (CB3) infection of A/J or A.SW mice results in autoimmune myocarditis characterized by a diffuse mononuclear cell infiltrate and heart-specific autoantibodies. C57BL/10 congenic mice that are identically treated are resistant to this disease. CB3-infected resistant B10.A mice were treated with LPS to determine if this immunomodulator alters disease susceptibility. In contrast to mice infected only with CB3 or treated only with LPS. CB3-infected/LPS-treated (CB3/LPS) B10.A mice developed autoimmune myocarditis similar to that observed in susceptible A/J or A.SW mice. By Day 14, CB3/LPS-induced disease was characterized by significant mortality, myocardial immunoglobulin deposition, and mononuclear cell infiltration of the heart. Immunohistochemical examination revealed deposits of IgG in the heart tissue and serum IgG autoantibodies reactive with sarcolemmal and fibrillary antigens in normal heart tissue. This serum IgG reacted with normal mouse cardiac antigens of a wide range of molecular weights by Western immunoblotting. Because LPS treatment is capable of increasing cytokine levels as well as MHC Class I and Class II expression in heart tissue, it suggests that these factors may contribute to susceptibility to autoimmune myocarditis in CB3-infected mice.     

Strain differences in the development of auto-anti-idiotypic antibody regulation with age: genetic linkage to the Igh-C locus

The effect of age on the appearance of anti-idiotype (Id)-blocked, hapten-augmentable plaque-forming cells (PFC) in various strains of mice was investigated. Strains of mice at 2 and 6-11 months of age were immunized with 500 micrograms trinitrophenylated bovine gamma-globulin (TNP-BGG) in complete Freund's adjuvant (CFA) intraperitoneally. Splenic IgM and IgG anti-TNP PFC responses were assayed for anti-Id-blocked, hapten-augmentable PFC 14 days after immunization. It was found that strains differ with regard to the age at which they produce anti-Id-blocked, hapten-augmentable PFC. C57BL/6J (B6), DBA/1J, and C3H/HeJ mice produced a significantly high percentage of hapten-augmentable IgG anti-TNP PFC at 8-9 months of age as compared with the 2-month-old group. In contrast, 129/J, AKR/J, and C57L/J mice produced a significantly low percentage of hapten-augmentable PFC at 6-7 months of age as compared with the 2-month-old group. The CBA/J mice were high-hapten-augmentable plaque producers at both 2 and 7 months of age. SJL/J mice were, on the other hand, low producers at 2 and 11 months of age. Immune sera from high hapten-augmentable plaque-producing strains caused a hapten-reversible block of plaque formation by spleen cells from TNP-BGG-immune C57BL/6J mice and also revealed anti-(anti-TNP F(ab')2-IgG) titer as assayed by passive hemagglutination. This PFC-inhibiting activity in the immune sera of old C57BL/6J mice was an antibody of the IgG2a and IgG3 classes, lacked anti-TNP antibody activity, but reacted with anti-TNP antibody of C57BL/6J origin. Genetic analysis between high hapten-augmentable plaque production and allotypes in the (129/J X B6) crosses of the same H-2b haplotypes revealed that all of the backcrosses and F2 with high hapten-augmentable plaque production had the Igh-1a allele of the high-producer, 129/J mouse. In contrast, the crosses with low hapten-augmentable plaque production were homozygous for the Igh-1b allele of the low-producer, B6 mouse. The data suggest strain differences in the development of auto-anti-idiotypic antibody regulation with age which may be controlled by a gene(s) linked to the Igh-C locus.     

A monoclonal anti-type II collagen antibody with cross-reactive anti-Ig activity specific for the F(ab')2 fragment

An IgG2a hybridoma antibody (BC-10) was obtained by a myeloma fusion with lymphocytes from B10.RIII mice immunized against native bovine type II collagen. This anti-collagen monoclonal exhibited extensive cross-reactivity with several type II collagen species. BC-10 was found to have self-associating properties, but not the specificity of a typical IgG rheumatoid factor, inasmuch as this mAb bound to F(ab')2 fragments of itself and of normal mouse IgG. Self binding was inhibited by the association of BC-10 with type II collagen, and inhibition assays indicated that antibodies with the capacity to inhibit BC-10 binding to collagen were present in the sera from B10.RIII arthritic mice, but not from DBA/1 LacJ arthritic mice. Joint inflammation and histopathologic features consistent with arthritis were observed in mice injected with the BC-10 hybridoma.     

Mouse senile amyloidosis. ASSAM amyloidosis in mice presents universally as a systemic age-associated amyloidosis.

Amyloid deposition in 11 inbred strains of mice (A/J, SJL/J, DDD, C57BL/6J, B10.BR, C57BL/10, B10A/SgSn, C3H/HeMs, B10A(5R), DBA/2 and C57BL/6Cr5/c) was studied using the peroxidase antiperoxidase (PAP) method and antisera against ASSAM and murine protein AA. Among the 170 mice examined, in 77 (45.3%) from the nine strains other than C3H/HeMs and DBA/2, there was evidence of spontaneous amyloid deposits in routine histological sections. Immunohistochemical studies using 54 mice with amyloid deposition, demonstrated ASSAM deposition in 45 mice (83.3%) in all nine strains, although the incidence and intensity of the deposition differed somewhat between strains. SJL/J and A/J had ASSAM deposits from the age of 8 months and the incidence increased with advancing age. In the other seven strains, ASSAM was first deposited at an older age than in the SJL/J and A/J strains. In A J, C57BL/6J, C57BL/10, B10.BR, B10A(5R) and C57BL/6Cr5/c, protein AA often coexisted with ASSAM. The distribution pattern of the ASSAM deposits was similar to that observed among the SAM strains. Thus, ASSAM is an ubiquitously distributed senile amyloid protein in the mouse. Determination of the molecular type of apoA-II, a serum precursor of ASSAM, among all 11 strains using the polymerase chain reaction (PCR) revealed the SAM-P/1 type apoA-II variant in SJL/J and A/J strains with a high susceptibility to ASSAM deposition. We concluded from this study that amino acid substitution in precursor apoA-II may be responsible for the early onset and severe amyloid deposition in the mouse.     

Isotype determination of anti-Trypanosoma cruzi antibody in murine Chagas' disease.

Isotypic analysis of anti-parasite humoral responses of C57B1/6 and C3H (He) mice surviving acute Trypanosoma cruzi infection showed that both mouse strains demonstrate IgG1, IgG2a, IgG2b, and IgM enzyme-linked immunosorbent assay titers from days 21 to 300 of infection. Using the western blot technique to determine the antigen specificity of the isotypic responses, 100-day infected C3H mice showed strong IgG1, IgG2a, and IgG2b responses to many antigens, whereas C57B1/6 mice showed weak responses to fewer antigens. Isotype western blots showed that reactivity to the T. cruzi antigen of 75-77 kDa is present in the humoral response of day 21-infected mice that will survive and missing in those that will not survive. In general, surviving immunized C3H mice respond with IgG1, IgG2a, and IgG2b reactions to the 75-77-kDa and other antigens, whereas resistant B6 mice concentrate their anti-T. cruzi response in the IgG2b isotype to the 75-77-kDa antigen. Perhaps induction of ineffective antibody responses to nonprotective antigens is beneficial to the parasite and detrimental to the host.     

Differential cardiac histopathology in inbred mouse strains chronically infected with Trypanosoma cruzi.

Seven inbred mouse strains were examined for the presence of chronic Chagas' cardiomyopathy in postacute Trypanosoma cruzi infection. DBA/1, DBA/2, BALB/c, B10.T (6R), B10.Q, B10.D2, and B6 mice were infected for 100 days with the Brazil strain of T. cruzi. Standard histologic examination of cardiac tissue from these mice revealed the following relationship among the different strains based on the severity of observed inflammation (myocarditis): BALB/c, DBA/1, and DBA/2 were the most inflamed; B10.T (6R) and B10.Q were intermediate; and B6 and B10.D2 showed the least inflammation. Examination of these tissues for characteristics of myocardiopathy such as cell swelling, edema, vacuolization, necrosis, myocytolysis, connective tissue infiltration, and thinning of the right ventricular wall indicated a relative relationship among the different strains relative to the severity of cardiomyopathy as follows: BALB/c, DBA/2, and DBA/1 showed the most cardiopathy (pathopermissive); B10.T (6R) and B10.Q showed intermediate pathology; and B6 and B10.D2 showed the least involvement (pathoresistant). Anti-heart antibody present in the sera of all these mice showed specific reactivity in western blots to a 43-kDa glycoprotein from normal heart tissue. Also, anti-heart antibody enzyme-linked immunosorbent assay titers for all mouse strains were similar and showed no correlation with the severity of tissue damage. The fact that different inbred strains show various degrees of myocarditis and cardiomyopathy may be useful in the study of pathogenesis of chronic Chagas' disease. Results from this limited list of inbred strains suggest that background genes, rather than the major histocompatibility complex, play the major role in the expression of cardiac pathogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

SARS-CoV-2重组S1和S蛋白疫苗诱导保护性免疫的研究*

目的:评价新型冠状病毒(SARS-CoV-2)重组S1蛋白和S蛋白疫苗对SARS-CoV-2的免疫保护效果。方法:将SARS-CoV-2重组S1蛋白和S蛋白分别联合氢氧化铝佐剂以0.1 μg/只、1 μg/只、5 μg/只、10 μg/只不同剂量接种6~8周BALB/c纯系健康雌性小鼠。第二次免疫后采血通过酶联免疫吸附试验(ELISA)检测血清中IgG抗体效价,通过假病毒中和试验比较免疫小鼠血清对SARS-CoV-2野生型株(WT)、英国株(B.1.1.7)、巴西株(P.1)、印度株(B.1.617.2)、Mu毒株(B.1.621)和南非株(501Y.V2-1)六种假病毒毒株中和活性效价,取脾细胞通过酶联免疫斑点技术(ELISpot)检测免疫小鼠的细胞免疫水平。结果:SARS-CoV-2重组S和S1蛋白都能诱导小鼠产生较强的IgG抗体水平。免疫S1蛋白的小鼠血清对SARS-CoV-2野生型株、英国株、巴西株有明显的中和活性,免疫S蛋白的小鼠血清除了对SARS-CoV-2野生型株、英国株、巴西株有明显中和活性之外,对印度株也有明显的中和活性,两种蛋白质免疫的小鼠血清均对野生型株中和效果最强。S蛋白免疫的小鼠脾细胞能够显著诱导出γ干扰素(IFN-γ)和白介素-4(IL-4)的产生。S蛋白诱导产生的IgG抗体、中和抗体、细胞免疫水平均高于S1。结论:SARS-CoV-2重组S蛋白疫苗能够诱导产生较强的保护性免疫应答。     

Immunoprotective murine monoclonal antibodies specific for the outer-core polysaccharide and for the O-antigen of Escherichia coli 0111:B4 lipopolysaccharide (LPS)

The antigen specificity of two immunoprotective monoclonal antibodies derived from mice immunized with Escherichia coli 0111:B4 bacteria and boosted with purified lipopolysaccharide (LPS) were investigated. One of the antibodies, B7, was shown by sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunostaining to bind to the O-antigen containing LPS species, whereas the other antibody, 5B10, reacted with both O-antigen containing homologs and the O-antigen-deficient LPS. 5B10 did not bind to LPS from E. coli J5, an Rc mutant of E. coli 0111:B4 that lacks both the O-antigen and outer core sugars. 5B10 did not cross-react with LPS from several other E. coli strains. Thus 5B10 appeared to recognize a type-specific epitope in the outer core of LPS exclusive of Rc determinants. The monoclonal antibody specific for the polymeric O-antigen is of the IgG3 subclass, and the monoclonal antibody 5B10 specific for the outer core of LPS is an IgG2a. Although B7 and 5B10 were equally able to protect mice from a lethal challenge of E. coli 0111:B4 organisms, the outer core-specific IgG2a antibody was much more efficient at mediating the binding of human complement C3 than the O-antigen-specific IgG3 monoclonal antibody.     

A new murine lymphocyte alloantigen,Ly-21.2, mapping to the seventh chromosome

Using a monoclonal antibody raised by fusing spleen cells from A/J mice, immunized with B10.A splenocytes and lymph-node cells, with a BALB/c myeloma, we have described a new surface alloantigen, Ly-21.2. Ly-21.2 is present in varying amounts in all lymphoid tissues, is not detectable in the brain, kidney, lung or erythrocytes, and is found in only trace amounts in the liver. Strain distribution studies showed that Ly-21.2 is present in all strains examined, including B10, except the A strain and segregation analysis of (A/J × 1310) F₂ mice showed that Ly-21.2 expression (1) is encoded by one gene and (2) is linked to albinism on chromosome 7. Studies performed on mice developing T-cell leukemia showed that, regardless of the etiologic agent, Ly-21.2 expression increases dramatically in mice with overt leukemia. In addition, preliminary studies suggest that expression of Ly-21.2 is linked to increased susceptibility of mice to Friend-virus-induced erythroleukemia.Abbreviations used in this paper B10 C57BL/10 - CPM counts per minute - FFU focus-forming units - FV Friend virus - i.v. intravenous - NMS normal mouse serum - PBS phosphate-buffered saline - RAMIG rabbit anti-mouse IgG - RIA radioimmunoassay     

Develope Monoclonal Antibody against Foot-and-mouth Disease Virus A Type

In order to develop an anti-FMDV A Type monoclonal antibody (mAb),BABL/c mice were immunized with FMDV A type.Monoclonal antibodies (mAbs) 7B11 and 8H4 against Foot-and-mouth disease virus (FMDV) serotype A were produced by fusing SP2/0 myeloma cells with splenocyte from the mouse immunized with A/AV88.The microneutralization titer of the mAbs 7B11 and 8H4 were 1024 and 512,respectively.Both mAbs contain kappa light chains,the mAbs were IgG1.In order to define the mAbs binding epitopes,the reactivity of the...     

Cardiac myosin induces myocarditis in genetically predisposed mice

After infection with coxsackie virus B3 (CB3), H-2 congenic mice on an A- background develop immunologically mediated myocarditis associated with an increased titer of myosin autoantibody, part of which is specific for the cardiac myosin isoform. The present study demonstrates that cardiac myosin itself induces severe myocarditis and high titers of myosin autoantibodies in A/J, A.SW/SnJ, and A.CA/SnJ mice. As in CB3-induced myocarditis, one population of these autoantibodies was specific for cardiac myosin. A.BY/SnJ and B10.A/SgSnJ mice also developed the disease after immunization, but the prevalence and the myosin autoantibody titers were lower. In contrast, C57BL/6J and C57BL/10J mice were resistant to myocarditis induced by cardiac myosin and did not develop increased myosin autoantibodies or cardiac myosin-specific autoantibodies. Immunization with skeletal muscle myosin had no effect compared with controls injected with complete Freund's adjuvant, thereby suggesting that the immunogenic epitopes are unique to the cardiac myosin isoform. Furthermore, we found that susceptibility to myocarditis induced by cardiac myosin is influenced by the major histocompatibility complex and by genes not closely linked to the major histocompatibility complex. Because there are parallels between myocarditis induced by cardiac myosin and that induced by CB3, this new animal model can be used to analyze the pathologic mechanisms in autoimmune heart disease.     

Evidence for differential induction of helper T cell subsets during Trichinella spiralis infection

The H-2-compatible mouse strains, AKR and B10.BR, exhibit disparate responses to infection with the parasitic nematode Trichinella spiralis. The resistant AKR mice expel intestinal adult worms faster than susceptible B10.BR mice. We tested antibody and lymphokine responses in these strains. With respect to antibody responses, the B10.BR mice had 3- to 10-fold more serum IgE and T. spiralis-specific IgG1 and IgA than AKR mice. The B10.BR mice also had greater numbers of IgG and IgA plaque-forming cells than AKR mice. In contrast, AKR mice produced T. spiralis-specific IgG2a, whereas the B10.BR mice did not. The antibody response kinetics of these strains were similar. We also analyzed lymphokine secretion after restimulating lymphocytes in vitro with T. spiralis Ag. The AKR mesenteric lymph node cells produced more IFN-gamma and less IL-4 than the B10.BR mesenteric lymph node cells. The B10.BR splenocytes produced more IL-4 than the AKR splenocytes, although splenocyte IFN-gamma production was not different. The kinetics of IL-4 production also differed between the two strains. In summary, resistant AKR mice produced more IFN-gamma and T. spiralis-specific IgG2a than susceptible B10.BR mice, which produced more IL-4, IgE, and T. spiralis-specific IgG1. Our results are consistent with differential activation of Th cell subsets in T. spiralis-infected AKR and B10.BR mice.     

Genetic regulation of the antibody response to H-2Db alloantigens in mice. IV. Antigens that activate helper T cells for IgG, coded for by the non-H-2 genome

When B10.A(5R) mice are immunized with congenic C57BL/10 cells only 2-ME-sensitive antibodies (IgM type) are found directed against H-2Db. To obtain 2-ME-resistant antibodies (IgG type) 5R mice must be immunized with noncongenic cells (e.g., A.BY); in this case non-H-2 cell surface antigens will activate helper T cells to induce anti-Db IgG antibody production by B cells. An attempt was made to define helper antigens that activate helper T cells. Neither N-2 antigens of seven H-2Db recombinant strains nor a limited set of non-H-2 cell surface antigens were able to serve as helper antigens. By using individual backcross mice as antigen, one helper antigen was found on the background of strain A under the conditions used, whereas other backgrounds may carry more than one antigen. The helper antigen is dominantly expressed in F1 mice and has to be presented on the same cell as H-2Db to induce the switch from IgM to IgG.     

Trypanosoma cruzi: serum antibody reactivity to the parasite antigens in susceptible and resistant mice

The specific antibody responses were compared among susceptible (A/Sn), moderately susceptible (Balb/c) and resistant (C57 BL/10J) mice infected with Trypanosoma cruzi (Y strain). Sera obtained during the second week of infection recognized a surface trypomastigote antigen of apparent Mr 80 kDa while displaying complex reactivity to surface epimastigote antigens. Complex trypomastigote antigens recognition was detected around the middle of the third week of infection. No major differences were observed along the infection, among the three strains of mice, neither in the patterns of surface antigen recognition by sera, nor in the titres of antibodies against blood trypomastigotes (lytic antibodies), tissue culture trypomastigotes or epimastigotes. On immunoblot analysis, however, IgG of the resistant strain displayed the most complex array of specificities against both trypo and epimastigote antigens, followed by the susceptible strain. IgM antibodies exhibited a more restricted antigen reactivity, in the three mouse strains studied. Balb/c sera (IgG and IgM) showed the least complex patterns of reactivity to antigens in the range of 30 kDa to 80 kDa. The onset of reactivity in the serum to trypomastigote surface antigens was also dependent on the parasite load to which the experimental animal was subjected.     

Noninvasive Assessment of Cardiac Abnormalities in Experimental Autoimmune Myocarditis by Magnetic Resonance Microscopy Imaging in the Mouse

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events of myocardial injuries, various mouse models of myocarditis have been widely used. This study involved experimental autoimmune myocarditis (EAM) induced with cardiac myosin heavy chain (Myhc)-α 334-352 in A/J mice; the affected animals develop lymphocytic myocarditis but with no apparent clinical signs. In this model, the utility of magnetic resonance microscopy (MRM) as a non-invasive modality to determine the cardiac structural and functional changes in animals immunized with Myhc-α 334-352 is shown. EAM and healthy mice were imaged using a 9.4 T (400 MHz) 89 mm vertical core bore scanner equipped with a 4 cm millipede radio-frequency imaging probe and 100 G/cm triple axis gradients. Cardiac images were acquired from anesthetized animals using a gradient-echo-based cine pulse sequence, and the animals were monitored by respiration and pulse oximetry. The analysis revealed an increase in the thickness of the ventricular wall in EAM mice, with a corresponding decrease in the interior diameter of ventricles, when compared with healthy mice. The data suggest that morphological and functional changes in the inflamed hearts can be non-invasively monitored by MRM in live animals. In conclusion, MRM offers an advantage of assessing the progression and regression of myocardial injuries in diseases caused by infectious agents, as well as response to therapies.     

Myosin autoimmunity is not essential for cardiac inflammation in acute Chagas' disease

Infection with the protozoan parasite Trypanosoma cruzi leads to acute myocarditis that is accompanied by autoimmunity to cardiac myosin in susceptible strains of mice. It has been difficult to determine the contribution of autoimmunity to tissue inflammation, because other inflammatory mechanisms, such as parasite-mediated myocytolysis and parasite-specific immunity, are coincident during active infection. To begin to investigate the contribution of myosin autoimmunity to myocarditis, we selectively inhibited myosin autoimmunity by restoring myosin tolerance via injection of myosin-coupled splenocytes. This tolerization regimen suppressed the strong myosin-specific delayed-type hypersensitivity (DTH) that normally develops in infected mice, although it did not affect myosin-specific Ab production. Suppression of myosin autoimmunity had no effect on myocarditis or cardiac parasitosis. In contrast, myosin tolerization completely abrogated myocarditis in mice immunized with purified myosin, which normally causes severe autoimmune myocarditis. In this case, myosin-specific DTH and Ab production were significantly reduced. We also examined the contribution of T. cruzi-specific immunity to inflammation by injection of T. cruzi-coupled splenocytes before infection. This treatment reduced T. cruzi DTH, although there was no effect on parasite-specific Ab production. Interestingly, cardiac inflammation was decreased, cardiac parasitosis was significantly increased, and mortality occurred earlier in the parasite-tolerized animals. These results indicate that myosin-specific autoimmunity, while a potentially important inflammatory mechanism in acute and chronic T. cruzi infection, is not essential for inflammation in acute disease. They also confirm previous studies showing that parasite-specific cell-mediated immunity is important for myocarditis and survival of T. cruzi infection.     

Strain variations in anti-sperm antibody responses and anti-fertility effects in inbred mice

This study provides evidence for polygenic controls of antisperm antibody levels in inbred male mice immunized with syngenic testis and epididymis. H2-linked and non-H2-linked genes were involved. Mice of H-2d haplotype were high responders, whereas those with H-2k haplotype were nonresponders; however, B10.D2/nSnJ mice (H-2d) were also nonresponders. In vitro fertilization inhibition by antisera correlated positively with the serum antisperm antibody levels, particularly with antibody of the immunoglobulin (Ig) G class. Inheritance of antibody response that inhibited in vitro fertilization (IVF) was an autosomal dominant trait, but this was not apparent for the control of antibody levels per se. Since IVF was inhibited by both IgG and fragment antigen-binding (Fab) isolated from immune sera, but not by immune IgG previously absorbed by sperm or testis, the biologic effect is antigen-specific and probably involved blockade of functional antigenic epitopes. Antisera to testis, caput sperm or cauda sperm were found to inhibit IVF to a similar degree. Inbred strains of mice that produced the highest levels of serum antisperm antibodies that inhibited IVF were A/J, SJL/J, DBA/1J and BALB/cByJ mice, and their antisera immunoprecipitated a common sperm antigen molecule of 35,000 to 40,000 Mr. In contrast, C57BL/6 and C57BL/10 mice produced significant antibody levels that had no effect on IVF, and their sera did not react with the 35,000- to 40,000-Mr peak. Moreover, among BALB/c H-2 congenic mice, only antiserum of responder BALB/cByJ (H-2d) mice immunoprecipitated the 35,000- to 40,000 Mr peak. Thus the 35,000- to 40,000-Mr protein may be of functional significance in the fertilization process.