Autoantibody Production In Mice Research Articles

The Role of Proprotein Convertases in the Regulation of the Function of Immune Cells in the Oncoimmune Response.

Proprotein convertases (PC) are a family of 9 serine proteases involved in the processing of cellular pro-proteins. They trigger the activation, inactivation or functional changes of many hormones, neuropeptides, growth factors and receptors. Therefore, these enzymes are essential for cellular homeostasis in health and disease. Nine PC subtilisin/kexin genes (PCSK1 to PCSK9) encoding for PC1/3, PC2, furin, PC4, PC5/6, PACE4, PC7, SKI-1/S1P and PCSK9 are known. The expression of PC1/3, PC2, PC5/6, Furin and PC7 in lymphoid organs such as lymph nodes, thymus and spleen has suggested a role for these enzymes in immunity. In fact, knock-out of Furin in T cells was associated with high secretion of pro-inflammatory cytokines and autoantibody production in mice. This suggested a key role for this enzyme in immune tolerance. Moreover, Furin through its proteolytic activity, regulates the suppressive functions of Treg and thus prevents chronic inflammation and autoimmune diseases. In macrophages, Furin is also involved in the regulation of their inflammatory phenotype. Similarly, PC1/3 inhibition combined with TLR4 stimulation triggers the activation of the NF-κB signaling pathway with an increased secretion of pro-inflammatory cytokines. Factors secreted by PC1/3 KD macrophages stimulated with LPS exert a chemoattractive effect on naive auxiliary T lymphocytes (Th0) and anti-tumoral activities. The link between TLR and PCs is thus very important in inflammatory response regulation. Furin regulates TL7 and TLR8 processing and trafficking whereas PC1/3 controls TLR4 and TLR9 trafficking. Since PC1/3 and Furin are key regulators of both the innate and adaptive immune responses their inhibition may play a major role in oncoimmune therapy. The role of PCs in the oncoimmune response and therapeutic strategies based on PCs inhibition are proposed in the present review.

Systemic translocation of Staphylococcus drives autoantibody production in HIV disease

BackgroundIncreased autoreactive antibodies have been reported in HIV disease; however, the mechanism accounting for autoantibody induction in HIV remains unknown.ResultsHerein, we show that seasonal influenza vaccination induces autoantibody production (e.g., IgG anti-nuclear antibody (ANA) and anti-double-stranded DNA antibody (anti-dsDNA)) in some viral-suppressed antiretroviral therapy (ART)-treated HIV+ subjects, but not in healthy controls. These autoantibodies were not derived from antigen-specific B cells but from activated “bystander” B cells analyzed by single-cell assay and by study of purified polyclonal ANAs from plasma. To explore the mechanism of autoantibody generation in HIV+ subjects, plasma level of microbial products, gene expression profile of B cells, and B cell receptor (BCR) repertoires were analyzed. We found that autoantibody production was associated with increased plasma level of microbial translocation; the patients with high autoantibodies had skewed B cell repertoires and upregulation of genes related to innate immune activation in response to microbial translocation. By analyzing circulating microbial 16S rDNA in plasma, the relative abundance of Staphylococcus was found to be associated with autoantibody production in HIV+ subjects. Finally, we found that injection of heat-killed Staphylococcus aureus promoted germinal center B cell responses and autoantibody production in mice, consistent with the notion that autoantibody production in HIV+ patients is triggered by microbial products.ConclusionsOur results showed that translocation of Staphylococcus can promote B cell activation through enhancing germinal center response and induces autoantibody production. It uncovers a potential mechanism linking microbial translocation and autoimmunity in HIV+ disease and provides a strong rationale for targeting Staphylococcus to prevent autoantibody production.

B-cell-intrinsic function of TAPP adaptors in controlling germinal center responses and autoantibody production in mice.

Control of B-cell signal transduction is critical to prevent production of pathological autoantibodies. Tandem PH domain containing proteins (TAPPs) specifically bind PI(3,4)P2, a phosphoinositide product generated by PI 3-kinases and the phosphatase SHIP. TAPP KI mice bearing PH domain-inactivating mutations in both TAPP1 and TAPP2 genes, uncoupling them from PI(3,4)P2, exhibit increased BCR-induced activation of the kinase Akt and develop lupus-like characteristics including anti-DNA antibodies and deposition of immune complexes in kidneys. Here, we find that TAPP KI mice develop chronic germinal centers (GCs) with age and show abnormal expression of B-cell activation and memory markers. Upon immunization with T-dependent Ag, TAPP KI mice develop functional but abnormally large GCs, associated with increased GC B-cell survival. Disruption of chronic GCs in TAPP KI mice by deletion of the costimulatory molecule ICOS abrogate anti-DNA and anti-nuclear antibody production in TAPP KI mice, indicating an essential role for GCs. Moreover, TAPP KI B cells are sufficient to drive chronic GC responses and recapitulate the autoimmune phenotype in BM chimeric mice. Our findings demonstrate a B-cell-intrinsic role of TAPP-PI(3,4)P2 interaction in regulating GC responses and autoantibody production and suggest that uncontrolled Akt activity in B cells can drive autoimmunity.

Human Diversity in a Cell Surface Receptor that Inhibits Autophagy

Mutations in genes encoding autophagy proteins have been associated with human autoimmune diseases, suggesting that diversity in autophagy responses could be associated with disease susceptibility or severity. A cellular genome-wide association study (GWAS) screen was performed to explore normal human diversity in responses to rapamycin, a microbial product that induces autophagy. Cells from several human populations demonstrated variability in expression of a cell surface receptor, CD244 (SlamF4, 2B4), that correlated with changes in rapamycin-induced autophagy. High expression of CD244 and receptor activation with its endogenous ligand CD48 inhibited starvation- and rapamycin-induced autophagy by promoting association of CD244 with the autophagy complex proteins Vps34 and Beclin-1. The association of CD244 with this complex reduced Vps34 lipid kinase activity. Lack of CD244 is associated with auto-antibody production in mice, and lower expression of human CD244 has previously been implicated in severity of human rheumatoid arthritis and systemic lupus erythematosus, indicating that increased autophagy as a result of low levels of CD244 may alter disease outcomes.

Friendly fire from organ failure

Graft Rejection These days organ transplantation may seem like a routine procedure, but rejection of the donated organ still poses a substantial risk. Autoantibodies contribute to rejection, but how these autoantibodies are generated remains unclear. Dieude et al. found that exosome-like vesicles derived from apoptotic endothelial cells stimulated autoantibody production in mice, which increased graft rejection. These vesicles contained active 20S proteasome core complexes; proteasome inhibition decreased both vesicle immunogenicity and graft rejection in transplanted mice. Circulating exosome-like vesicles and increased anti-autoantibody titers were also observed in mouse models of vascular injury, suggesting that the same organ failure that necessitates the transplant might increase the risk of rejection. Sci. Transl. Med. 7 , 318ra200 (2015).

CD275/ICOSL-independent germinal centers and autoantibody in autoimmune-prone RasGRP1-deficient mice (BA13P.125)

Abstract Lymphopenia results in favorable microenvironments for the expansion and activation of autoreactive lymphocytes. Mice deficient in guanine nucleotide exchange factor Rasgrp1 (KO) are T lymphopenic early in life and develop a lymphoproliferative disorder with features of human SLE. Our previous work revealed that autoreactive B cells lacking RasGRP1 break tolerance early during development as well as during germinal center responses, suggesting both T cell-independent and -dependent mechanisms are responsible. To understand whether T cells are involved in the breach of tolerance in germinal centers, we examined T effector cells in KO mice. In addition to the expected increase in Th1 cells, the frequency and number of Th17 cells were also elevated in KO mice. Th17 cells were positive for CXCR5 and Bcl-6, localized to germinal centers and upregulated levels of CD278/ICOS coordinately with the appearance of germinal centers, all attributes of T follicular helper cells (Tfh17). To determine whether CD278-CD275 interactions were required for the development of Tfh17 cells and for autoantibody, we crossed KO and CD275-deficient mice. Interestingly, KO mice lacking CD275 formed germinal centers with an elevated frequency of Th17 cells and similar titers of autoantibodies. From these data, we suggest that CD278-CD275 interactions are not required for germinal centers and autoantibody production in mice lacking RasGRP1.

Requirement for MyD88 Signaling in B Cells and Dendritic Cells for Germinal Center Anti-Nuclear Antibody Production in Lyn-Deficient Mice

The intracellular tyrosine kinase Lyn mediates inhibitory receptor function in B cells and myeloid cells, and Lyn(-/-) mice spontaneously develop an autoimmune and inflammatory disease that closely resembles human systemic lupus erythematosus. TLR-signaling pathways have been implicated in the production of anti-nuclear Abs in systemic lupus erythematosus and mouse models of it. We used a conditional allele of Myd88 to determine whether the autoimmunity of Lyn(-/-) mice is dependent on TLR/MyD88 signaling in B cells and/or in dendritic cells (DCs). The production of IgG anti-nuclear Abs, as well as the deposition of these Abs in the glomeruli of the kidneys, leading to glomerulonephritis in Lyn(-/-) mice, were completely abolished by selective deletion of Myd88 in B cells, and autoantibody production and glomerulonephritis were delayed or decreased by deletion of Myd88 in DCs. The reduced autoantibody production in mice lacking MyD88 in B cells or DCs was accompanied by a dramatic decrease in the spontaneous germinal center (GC) response, suggesting that autoantibodies in Lyn(-/-) mice may depend on GC responses. Consistent with this view, IgG anti-nuclear Abs were absent if T cells were deleted (TCRβ(-/-) TCRδ(-/-) mice) or if T cells were unable to contribute to GC responses as the result of mutation of the adaptor molecule SAP. Thus, the autoimmunity of Lyn(-/-) mice was dependent on T cells and on TLR/MyD88 signaling in B cells and in DCs, supporting a model in which DC hyperactivity combines with defects in tolerance in B cells to lead to a T cell-dependent systemic autoimmunity in Lyn(-/-) mice.

PRODUCTION OF CROSS-REACTIVE AUTOANTIBODY BINDING TO BOVINE SERUM ALBUMIN IN THE D-GALACTOSE-INDUCED AGING MOUSE MODEL

The D-galactose (D-gal)-induced animal model, generated by repeated subcutaneous D-gal injections over approximately 6 weeks, has been frequently used for diabetes and aging research. However, little research has investigated the direct correlation between D-gal and autoantibody formation despite several reports on diabetes-and aging-related autoantibodies. The purpose of this study was to determine whether repetitive injection of D-gal can induce autoantibody production in mice. First, we used Bovine Serum Albumin (BSA) and Advanced Glycation End products (AGE)-BSA as the test antigens. The immunoreactivity of serum samples from mice treated with D-gal for 6 weeks was evaluated using Enzyme-Linked Immunosorbent Assay (ELISA). We found that serum samples of D-gal-treated mice had significantly high antibody titers against both BSA and AGE-BSA. Furthermore, the result showed that aminoguanidine treatment, an AGE inhibitor tended to decrease this immunoreactivity. The results of competitive inhibition ELISA using BSA and AGE-BSA as the competitors suggested that the serum samples from D-gal-treated mice contained antibodies not only against BSA but also specific to AGE-BSA. To assess whether the immunoreactivity against BSA is comparable to that against Mouse Serum Albumin (MSA), we examined the reactivity of D-gal-induced antibodies against MSA. Unexpectedly, D-gal-induced antibodies did not react with MSA. This suggests that the production of antibodies by D-gal is in response to an unknown antigen(s), aside from MSA, in mice and that this unknown antigen(s) may share similar sequences or three-dimensional structures with BSA.

TRAF6 is a critical regulator of LMP1 functionsin vivo

EBV-encoded latent membrane protein 1 (LMP1) is critical for EBV-driven B-cell transformation and most EBV-associated malignancies and is also implicated in exacerbation of autoimmunity. LMP1 functionally mimics the TNFR superfamily member CD40, but LMP1-induced signals and downstream B-cell functions are amplified and sustained compared with those mediated by CD40. CD40 and LMP1 both depend upon TNFR-associated factor (TRAF) adaptor molecules to mediate signaling but use them differently. LMP1 is dependent upon TRAFs 3 and 5 to deliver B-cell activation signals, while CD40 predominantly uses TRAFs 2 and 6 for this purpose. Both LMP1 and CD40 functions in B cells require TRAF6, which physically associates with both receptors but via different binding sites. In B-cell CD40 signaling, TRAF6 is required for a particular subset of CD40-dependent immune functions in vivo. Inasmuch as CD40 and LMP1 use other TRAFs differentially, we predicted that TRAF6 is critical for a specific subset of LMP1 functions in vivo and that this subset will be overlapping but distinct from the TRAF6-requiring functions of CD40. This study tests this prediction using a B-cell-specific TRAF6-deficient mouse model. We found that B-cell TRAF6 is important for LMP1-mediated antibody and autoantibody production in mice, as well as germinal center formation, but not the secondary lymphoid organ enlargement that results from LMP1 transgenic expression. Results highlight differential TRAF6 requirements for specific B-cell functions by LMP1 versus CD40. These differences may make important contributions to the contrasts between normally regulated CD40 versus pathogenic LMP1-mediated signals.

Amphibole, but not chrysotile, asbestos induces anti-nuclear autoantibodies and IL-17 in C57BL/6 mice

Exposure to amphibole asbestos has been associated with production of autoantibodies in mice and humans, and increases the risk of systemic autoimmune disease. However, epidemiological studies of chrysotile exposure have not indicated a similar induction of autoimmune responses. To demonstrate this difference in controlled exposures in mice, and to explore possible mechanistic explanations for the difference, C57BL/6 mice were exposed intratracheally to amphibole or chrysotile asbestos, or to saline only. Serum antinuclear antibodies (ANA), antibodies to extractable nuclear antigens (ENA), serum cytokines, and immunoglobulin isotypes were evaluated 8 months after the final treatment. The percentages of lymphocyte sub-sets were determined in the spleen and lungs. The results show that amphibole, but not chrysotile, asbestos increases the frequency of ANA/ENA in mice. Amphibole and chrysotile both increased multiple serum cytokines, but only amphibole increased IL-17. Both fibers decreased IgG1, without significant changes in other immunoglobulin isotypes. Although there were no gross changes in overall percentages of T- and B-cells in the spleen or lung, there was a significant increase in the normally rare populations of suppressor B-cells (CD19+, CD5+, CD1d+) in both the spleen and lungs of chrysotile-exposed mice. Overall, the results suggest that, while there may be an inflammatory response to both forms of asbestos, there is an autoimmune response in only the amphibole-exposed, but not the chrysotile-exposed mice. These data have critical implications in terms of screening and health outcomes of asbestos-exposed populations.

Accumulation of splenic plasma cells in lyn−/− mice is dependent on Bruton's tyrosine kinase but not IL‐6

Deficiency of Lyn, a negative regulator of B and myeloid cell activation, results in B cell hyperresponsiveness, plasma cell accumulation, and production of autoantibodies in mice. Since accumulation of peripheral plasma cells is a common feature of both human and murine lupus, we have studied the mechanisms regulating this process in lyn−/− mice. Lyn‐deficient mice expressing reduced dosage of Btk (Btklo), a target of Lyn‐dependent inhibitory pathways, retain hypersensitivity to B cell receptor crosslinking but do not demonstrate increased plasma cell numbers or produce autoantibodies. Bone marrow‐derived macrophages from lyn−/− mice secrete more IL‐6, which promotes plasma cell differentiation and survival, than do wild type cells upon stimulation with LPS. Intracelluar staining for IL‐6 in splenic CD11b+ cells reveals that a greater frequency of lyn−/− myeloid cells produce IL‐6 upon LPS exposure than do wild type cells. Also, sera IL‐6 is significantly increased in aged lyn−/− mice. To determine if these effects are Btk‐mediated, we examined lyn−/−btklo mice and found that both production of IL‐6 in splenic CD11b+ cells and sera IL‐6 levels are normalized in lyn−/−btklo mice. However, lyn−/−IL‐6−/− mice continue to exhibit both plasma cell accumulation and production of anti‐DNA antibodies. Thus, plasma cell and autoimmune phenotypes in lyn−/− mice are mediated by Btk but not IL‐6.

Macrophages and Dendritic Cells Use Different Axl/Mertk/Tyro3 Receptors in Clearance of Apoptotic Cells

The clearance of apoptotic cells is important for regulating tissue homeostasis, inflammation, and autoimmune responses. The absence of receptor tyrosine kinases (Axl, Mertk, and Tyro3) results in widespread accumulation of apoptotic cells and autoantibody production in mice. In this report, we examine the function of the three family members in apoptotic cell clearance by different phagocytic cell types. Mertk elimination nearly abolished macrophage apoptotic cell phagocytosis; elimination of Axl, Tyro3, or both, reduced macrophage phagocytosis by approximately half, indicating that these also play a role. In contrast, apoptotic cell clearance in splenic and bone marrow-derived dendritic cells (DCs) is prolonged compared with macrophages and relied primarily on Axl and Tyro3. The slower ingestion may be due to lower DC expression of Axl and Tyro3 or absence of GAS6 expression, a known ligand for this receptor family. In vivo, phagocytosis of apoptotic material by retinal epithelial cells required Mertk. Unlike macrophages, there did not appear to be any role for Axl or Tyro3 in retinal homeostasis. Likewise, clearance of apoptotic thymocytes in vivo was dramatically reduced in mertk(kd) mice, but was normal in axl/tyro3(-/-) mice. Thus, cell and organ type specificity is clearly delineated, with DCs relying on Axl and Tyro3, retina and thymus requiring Mertk, and macrophages exhibiting an interaction that involves all three family members. Surprisingly, in macrophages, tyrosine phosphorylation of Mertk in response to apoptotic cells is markedly diminished from axl/tyro3(-/-) mice, suggesting that the interactions of these receptors by heterodimerization may be important in some cells.

Interleukin-4 Produces a Breakdown of Tolerance in vivo with Autoantibody Formation and Tissue Damage

B cell susceptibility to Fas-mediated apoptosis is downmodulated by engagement of IL-4 and sIg receptors. IL-4 produces Fas-resistance in both normal and tolerant B lymphocytes and has been associated with autoantibody production in mice expressing heterogeneous B cell receptors. To study the in vivo effects of IL-4 on autoreactive B cells in a more well-defined system, mice triply transgenic for IL-4, soluble HEL and anti-HEL B cell receptors were generated. Anti-HEL/sHEL/IL-4 triple transgenic mice matured normally but accumulated increasing amounts of serum anti-HEL antibodies over time, whereas anti-HEL/sHEL double transgenic mice lacked serum anti-HEL. Autoantibodies in triple transgenic mice were accompanied by gross evidence of renal pathology, characterized by both abnormal histology and marked proteinuria, along with microscopic evidence of immune complex-type hepatic damage. Proteinuria and histopathological changes were also observed in IL-4 transgenic control mice. These results suggest that IL-4 induced a breakdown in tolerance and autoreactive B cell activity manifested by the onset and accumulation of autoantibodies and the development of frank autoimmune disease.

Epitope-dependent inhibition of T cell activation by the Ea transgene: an explanation for transgene-mediated protection from murine lupus.

A high level expression of the Ea(d) transgene encoding the I-E alpha-chain is highly effective in the suppression of lupus autoantibody production in mice. To explore the possible modulation of the Ag-presenting capacity of B cells as a result of the transgene expression, we assessed the ability of the transgenic B cells to activate Ag-specific T cells in vitro. By using four different model Ag-MHC class II combinations, this analysis revealed that a high transgene expression in B cells markedly inhibits the activation of T cells in an epitope-dependent manner, without modulation of the I-E expression. The transgene-mediated suppression of T cell responses is likely to be related to the relative affinity of peptides derived from transgenic I-E alpha-chains (Ealpha peptides) vs antigenic peptides to individual class II molecules. Our results support a model of autoimmunity prevention based on competition for Ag presentation, in which the generation of large amounts of Ealpha peptides with high affinity to I-A molecules decreases the use of I-A for presentation of pathogenic self-peptides by B cells, thereby preventing excessive activation of autoreactive T and B cells.

Generation of B220low B cells and production of autoantibodies in mice with experimental amyloidosis: association of primordial T cells with this phenomenon.

To investigate the immunological state in amyloidosis, mice were twice intraperitoneally injected (2-week interval) with casein emulsified in complete Freund's adjuvant. Two weeks after the treatment, amyloid deposits were detected in the spleen and other organs of these mice. The number of lymphocytes yielded by the liver and spleen increased significantly. The most affected lymphocyte subset was found to be B cells, namely, the total number of B cells increased and unusual B220low B cells were newly generated in the liver and spleen. In other words, not only normal B220high B cells but also unusual B220low B cells were detected in these organs of mice with amyloidosis. In parallel with this phenomenon, autoantibodies against denatured DNA were detected in sera. Since such autoantibodies are known to accompany the functional activation of NKT cells, NKT cell-deficient mice were used for the induction of amyloidosis. Such mice showed less formation of amyloidosis and lower levels of autoantibodies in sera. Athymic nude mice were NKT cell-deficient but NK1.1- TCRint cells were present. These athymic mice showed an intermediate induction of amyloidosis. The cytokine profile seen in mice with amyloidosis was the Th0 type, showing simultaneous production of IL-4 and IFNgamma. These results suggest that the generation of B220low B cells and the production of autoantibodies in aid of primordial T cells may be major immunological mechanisms in amyloidosis mice.

Yersinia Enterocolitica O:3 Isolated from Patients with or without Reactive Arthritis Induces Polyclonal Activation of B Cells and Autoantibody Production In Vivo

The mechanisms by which arthritis-provoking pathogens such as Yersinia enterocolitica interact with the human immune system to produce inflammatory synovitis are not well known. One of the immunomodulating mechanisms used against these pathogens is the polyclonal activation of lymphocytes. In this study, we investigated the extent of the B-lymphocyte activation induced in mice by a strain of Y. enterocolitica O:3 (FCF 526) isolated from a patient with arthritis, and compared it with two other strains, a virulent one (FCF 397[+]) isolated from a patient without arthritis and its plasmidless isogenic pair (FCF397[-]). Also we investigated the production of autoantibodies in mice infected with these different strains. SPF Swiss mice were infected intravenously with a suspension of Y. enterocolitica. Spleen cells were taken on days 7, 14, 21 and 28 after infection and the number of cells secreting nonspecific and specific antibodies of IgG1, IgG2a, IgG2b, IgG3, IgM and IgA isotypes were determined by the ELISPOT technique. The presence of autoantibodies in mouse serum was investigated by the dot-blot assay. The pattern of infection of the three bacterial strains were almost the same. We observed a general increase in the number of nonspecific Ig-secreting cells with all three strains, and the greatest increases observed were in the IgG2a and IgG3 isotypes. Only a small fraction of the immunoglobulins detected were antibacterial, suggesting that the rest resulted from polyclonal B cell activation. The strain isolated from the patient with arthritis (FCF526) induced the greatest production of autoantibodies, coinciding with the period in which the greatest activation of nonspecific B lymphocytes was seen. There were no signs of arthritis or inflammation in the joints of the infected animals. Based on our results, we were unable to determine whether there is an association between the arthritogenic capability of Y. enterocolitica and polyclonal activation of B cells.

HEMA bound to self-protein promotes auto-antibody production in mice.

While several studies report that acrylic monomers contained in dental materials may cause hypersensitivity reactions, little is known of the associated immune response. Here we address the potential of 2-hydroxyethyl-methacrylate (HEMA) to bind to endogenous protein and elicit auto-antibody production in vivo. Albumin was incubated with HEMA at various times and pH. Following confirmation of the conjugation by inhibition of trinitrophenyl (TNP) binding, female Balb/c mice received HEMA conjugated to mouse serum albumin (MSA) in Freund's incomplete adjuvant or saline subcutaneously. ELISA was used to determine the serum antibody responses to native and modified MSA. IL-2 production in spleen cell cultures stimulated with HEMA-conjugated MSA was measured. HEMA reacted with serum albumin at physiological conditions. HEMA-conjugated MSA induced IL-2 secretion and production of IgG antibodies to native MSA. The results suggest that modification of an endogenous protein like serum albumin with HEMA may defeat the control of immune responses to this self-protein.

Simultaneous activation of natural killer T cells and autoantibody production in mice injected with denatured syngeneic liver tissue.

Denatured syngeneic liver tissue prepared by mechanical procedures was intraperitoneally injected into adult C57BL/6 mice. In parallel with a decrease in the total number of lymphocytes in the liver, spleen, and thymus from days 1-7 after the injection, the proportion of the CD4+NK1.1+CD3(int) subset of these cells (i.e. natural killer T or NKT cells) increased in the liver. Even the absolute number of these NKT cells increased in the liver on days 14 and 21. In response to the injection of denatured liver tissue, tissue damage was induced in the liver, as shown by elevated levels of serum transaminases and hepatocyte degeneration observed by electron microscopy. Sera obtained on days 7 and 14 contained autoantibodies including anti-DNA antibodies. The proportion of CD1d(high)B cells in the liver was found to decrease on days 1-7. In other words, denatured liver tissue stimulated both NKT cells and certain B cells in the liver. These results suggest that liver lymphocytes might contain not only autoreactive T cells (e.g. CD3(int) or NKT cells) but also some B cells (e.g. B-1 cells) which produce autoantibodies and that the denatured tissue had the potential to stimulate these lymphocytes and to evoke an autoimmune-like state.

Subacute toxicity of (-)15-deoxyspergualin in BALB/c mice. I. Hematological study.

(-)15-Deoxyspergualin (DSP), a bacterial metabolite obtained from Bacillus laterosporus, was shown to effectively suppress autoantibody production in mice and alloimmune reaction in mice and rats. Its potential toxicity and safety margin in BALB/c mice were studied by administering the drug, 0.5-5.0 mg/kg body weight, s.c., 6 days/week for 3 months. The animals were weighted every two weeks, and their blood was drawn for hematological and liver function studies. Control animals showed a gradual increase in body weight from 17.8 +/- 1.1 g (SD) to 20.2 +/- 3.2 g during the 3 months of treatment. The body weight of 0.5 mg- and 2.5 mg-DSP group was not significantly different from that of the control group. In contrast, 5.0 mg-DSP group of animals showed significant decrease in their weight compared with the control after 5 weeks of treatment (P less than 0.01). They were then sacrificed. WBC in 0.5 mg-, 2.5 mg- and 5.0 mg-DSP groups were significantly lower compared with the control after 3 months of treatment. On the other hand, only 5.0 mg-DSP group showed significantly lower level in their RBC, Hb and Hct values (P less than 0.05). In contrast, platelet counts in 2.5 mg- and 5.0 mg-DSP group significantly increased. No manifest effect due to DSP on differential count of leukocytes was observed, although on day 92, a significant difference was shown in the stab cells of the 0.5 mg-DSP group and in the eosinophils in the 2.5 mg-DSP.(ABSTRACT TRUNCATED AT 250 WORDS)

Carrier‐Specific Induction of Suppressor Cells Controlling Anti‐Erythrocyte Autoantibody Production in Mice

Mice immunized with rat erythrocytes develop anti-erythrocyte autoantibodies, distinct anti-rat erythrocyte agglutinins, and suppressor-inducer cells, which regulate the production of autoantibody but not anti-rat erythrocyte agglutinins upon transfer to naive recipients. In this report, we have tried to determine the specificity of the suppressor-inducer cells. CBA/N mice (which express an X-linked genetic B-lymphocyte defect) immunized with rat erythrocytes developed no autoantibodies but normal levels of anti-rat erythrocyte antibodies and suppressor-inducer cells, thereby suggesting that neither idiotypes on autoreactive B cells nor idiotypes on autoantibody itself, stimulate suppressor-inducer cells. In contrast, rat erythrocyte-primed spleen cells suppressed both a primary 2,4,6 trinitrophenyl (TNP) response and anti-erythrocyte autoantibody production (but not anti-rat erythrocyte antibodies) upon transfer to naive recipients and challenge with TNP-rat erythrocytes. It is considered that the suppressor-inducer cells are carrier-specific and that they are not stimulated by idiotypes on either autoantibody or autoreactive B cells.