Cytokines and Ly-1 (B1) B cells

Modulation of microbiome diversity and cytokine expression is influenced in a sex-dependent manner during aging

The microbiome and immune system have a unique interplay, which influences homeostasis within the organism. Both the microbiome and immune system play important roles in health and diseases of the aged including development of cancer, autoimmune disorders, and susceptibility to infection. Various groups have demonstrated divergent changes in the gut microbiota during aging, yet the compounding factor of biological sex within the context of aging remains incompletely understood, and little is known about the effect of housing location in the composition of gut microbiota in the context of both sex and age. To better understand the roles of sex, aging, and location in influencing the gut microbiome, we obtained normal healthy BALB/cByJ mice from a single source and aged male and female mice in two different geographical locations. The 16S rRNA was analyzed from fecal samples of these mice and cytokine levels were measured from serum.16S rRNA microbiome analysis indicated that both age and sex play a role in microbiome composition, whereas location plays a lesser role in the diversity present. Interestingly, microbiome changes occurred with alterations in serum expression of several different cytokines including IL-10 and IL-6, which were also both differentially regulated in context to sex and aging. We found both IL-10 and IL-6 play a role in the constitutive expression of pSTAT-3 in CD5+ B-1 cells, which are known to regulate the microbiome. Additionally, significant correlations were found between cytokine expression and significantly abundant microbes. Based on these results, we conclude aging mice undergo sex-associated alterations in the gut microbiome and have a distinct cytokine profile. Further, there is significant interplay between B-1 cells and the microbiome which is influenced by aging in a sex-dependent manner. Together, these results illustrate the complex interrelationship among sex, aging, immunity, housing location, and the gut microbiome.

Host immune response against leishmaniasis and parasite persistence strategies: A review and assessment of recent research

Leishmaniasis, a neglected parasitic disease caused by a unicellular protozoan of the genus Leishmania, is transmitted through the bite of a female sandfly. The disease remains a major public health problem and is linked to tropical and subtropical regions, with an endemic picture in several regions, including East Africa, the Mediterranean basin and South America. The different causative species display a diversity of clinical presentations; therefore, the immunological data on leishmaniasis are both scarce and controversial for the different forms and infecting species of the parasite. The present review highlights the main immune parameters associated with leishmaniasis that might contribute to a better understanding of the pathogenicity of the parasite and the clinical outcomes of the disease. Our aim was to provide a concise overview of the immunobiology of the disease and the factors that influence it, as this knowledge may be helpful in developing novel chemotherapeutic and vaccine strategies.

How to B(e)-1 Important Cell During Leishmania Infection

B-1 cells are an innate-like population of B lymphocytes that are subdivided into B-1a and B-1b distinguished by the presence or absence of CD5, respectively. B-1 cells can act as regulatory B cells, are able to present antigen and produce IL-10. Leishmaniasis in humans is a complex of diseases caused by parasites of the genus Leishmania. More than 20 species can infect humans, with each species causing the development of different immunological responses in the host. Susceptibility is usually related to the production of anti-inflammatory cytokines while the production of Th1 cytokines is indicative of resistance. However, few studies have attempted to evaluate the role of B-1 cells during either the in vivo infection or in vitro interaction with Leishmania parasites. In vivo studies were performed using XID mice model, BALB/Xid mice have a mutation in the Bruton's tyrosine kinase, which is an important enzyme for developing B-1 and maturing B-2 lymphocytes leading to the presence of immature B-2 cells. Here, we compile these studies and assess the influence of B-1 cells on disease progression with different Leishmania species.

Potential importance of B cells in aging and aging-associated neurodegenerative diseases

Our understanding of B cells as merely antibody producers is slowly changing. Alone or in concert with antibody, they control outcomes of seemingly different diseases such as cancer, rheumatoid arthritis, diabetes, and multiple sclerosis. While their role in activation of effector immune cells is beneficial in cancer but bad in autoimmune diseases, their immunosuppressive and regulatory subsets (Bregs) inhibit autoimmune and anticancer responses. These pathogenic and suppressive functions are not static and appear to be regulated by the nature and strength of inflammation. Although aging increases inflammation and changes the composition and function of B cells, surprisingly, little is known whether the change affects aging-associated neurodegenerative disease, such as Alzheimer's disease (AD). Here, by analyzing B cells in cancer and autoimmune and neuroinflammatory diseases, we elucidate their potential importance in AD and other aging-associated neuroinflammatory diseases.

Regulatory T Cell Dysfunction Acquiesces to BTLA+ Regulatory B Cells Subsequent to Oral Intervention in Experimental Autoimmune Encephalomyelitis

Regulatory T cells (Tregs) induced during autoimmunity often become quiescent and unable to resolve disease, suggesting inadequate activation. Resolution of established experimental autoimmune encephalomyelitis (EAE) can be achieved with myelin oligodendrocyte glycoprotein (MOG) fused to reovirus protein σ1 (MOG-pσ1), which activates Tregs, restoring protection, but requiring other regulatory cells to revitalize them. B cells have a dichotomous role in both the pathogenesis and recovery from EAE. Although inflammatory B cells contribute to EAE's pathogenesis, treatment of EAE mice with MOG-pσ1, but not OVA-pσ1, resulted in an influx of IL-10-producing B220(+)CD5(+) B regulatory cells (Bregs) enabling Tregs to recover their inhibitory activity, and in turn, leading to the rapid amelioration of EAE. These findings implicate direct interactions between Bregs and Tregs to facilitate this recovery. Adoptive transfer of B220(+)CD5(-) B cells from MOG-pσ1-treated EAE or Bregs from PBS-treated EAE mice did not resolve disease, whereas the adoptive transfer of MOG-pσ1-induced B220(+)CD5(+) Bregs greatly ameliorated EAE. MOG-pσ1-, but not OVA-pσ1-induced IL-10-producing Bregs, expressed elevated levels of B and T lymphocyte attenuator (BTLA) relative to CD5(-) B cells, as opposed to Tregs or effector T (Teff) cells, whose BTLA expression was not affected. These induced Bregs restored EAE Treg function in a BTLA-dependent manner. BTLA(-/-) mice showed more pronounced EAE with fewer Tregs, but upon adoptive transfer of MOG-pσ1-induced BTLA(+) Bregs, BTLA(-/-) mice were protected against EAE. Hence, this evidence shows the importance of BTLA in activating Tregs to facilitate recovery from EAE.

Regulatory B cells mediate tolerance to apoptotic self in health: implications for disease

B cells are able to regulate immune responses through the secretion of IL-10 and other inhibitory cytokines, though no transcription factor that can define 'regulatory B cells' as a separate lineage has yet been found. Instead it is likely that this function arises as a result of the immune context in which B cells find themselves and the stimuli they perceive. However, some B cells found within the B1a and the marginal zone subsets have a greater propensity to produce IL-10 than others. What are the natural stimuli for these cells to induce immune regulation? We discuss the role that the recognition of autoantigens exposed by apoptotic cells plays in stimulating IL-10 production in mouse and human studies. This mechanism involves the recognition and uptake of self-antigens by autoreactive BCRs, for delivery to endocytic compartments, where apoptosis-derived DNA binds to TLR9, driving IL-10 production. These 'natural' regulatory B cells represent a way of maintaining tolerance to self. We discuss how this may operate in inflammatory lesions where there is an excess of apoptotic leukocytes and how this impacts on our understanding of autoimmune disease.

The role of type 2 innate lymphoid cells in asthma

Asthma is a complex and heterogeneous disease with several phenotypes, including an allergic asthma phenotype, characterized by Th2 cytokine production and associated with allergen sensitization and adaptive immunity. Asthma also includes nonallergic asthma phenotypes that require innate rather than adaptive immunity. These innate pathways to asthma involve macrophages, neutrophils, as well as ILCs, newly described cell types that produce a variety of cytokines, including IL-5 and IL-13. We review the recent data regarding ILCs and their role in asthma.

Food components and the immune system: from tonic agents to allergens

The intestinal mucosa is the major site of contact with antigens, and it houses the largest lymphoid tissue in the body. In physiological conditions, microbiota and dietary antigens are the natural sources of stimulation for the gut-associated lymphoid tissues (GALT) and for the immune system as a whole. Germ-free models have provided some insights on the immunological role of gut antigens. However, most of the GALT is not located in the large intestine, where gut microbiota is prominent. It is concentrated in the small intestine where protein absorption takes place. In this review, we will address the involvement of food components in the development and the function of the immune system. Studies in mice have already shown that dietary proteins are critical elements for the developmental shift of the immature neonatal immune profile into a fully developed immune system. The immunological effects of other food components (such as vitamins and lipids) will also be addressed. Most of the cells in the GALT are activated and local pro-inflammatory mediators are abundant. Regulatory elements are known to provide a delicate yet robust balance that maintains gut homeostasis. Usually antigenic contact in the gut induces two major immune responses, oral tolerance and production of secretory IgA. However, under pathological conditions mucosal homeostasis is disturbed resulting in inflammatory reactions such as food hypersensitivity. Food allergy development depends on many factors such as genetic predisposition, biochemical features of allergens, and a growing array of environmental elements. Neuroimmune interactions are also implicated in food allergy and they are examples of the high complexity of the phenomenon. Recent findings on the gut circuits triggered by food components will be reviewed to show that, far beyond their role as nutrients, they are critical players in the operation of the immune system in health and disease.

Epstein-Barr virus LMP2A increases IL-10 production in mitogen-stimulated primary B-cells and B-cell lymphomas

Epstein-Barr virus (EBV) latently infected B-cells are the precursors of EBV-associated malignancies. EBV-infection induces the production of pro-survival and anti-inflammatory cytokines that may be important in the transition between latency and malignancy. One EBV protein, LMP2A, can be detected in both latently infected resting B-cells and in EBV-associated malignancies. Therefore, we tested the ability of LMP2A to influence cytokine production using both LMP2A-Tg primary B-cells and LMP2A-expressing B-cell lines. Our data demonstrate that LMP2A does not globally alter B-cell-produced cytokine levels, but specifically targets IL-10. Additional studies using ELISA and real-time-RT-PCR confirm that LMP2A utilizes PI3-kinase to increase IL-10 levels. Finally, the data demonstrate that LMP2A-expressing B-cell lines are more dependent on IL-10 for survival in comparison to LMP2A-negative B-cell lines. These data identify a novel function of LMP2A in the alteration of a cytokine that is important for both tumour survival and anti-tumour responses.

Type 2 innate lymphoid cells: friends or foes-role in airway allergic inflammation and asthma

Innate-like lymphocytes (ILLs) and innate lymphoid cells (ILCs) are two newly characterized families of lymphocytes with limited and no rearranged antigen receptors, respectively. These soldiers provide a first line of defense against foreign insults by triggering a prompt innate immune response and bridging the gap of innate and adaptive immunity. Type 2 innate lymphoid cells (ILCs2) are newly identified members of the ILC family that play a key role in type 2 immune responses by prompt production of type 2 cytokines (especially IL-5 and IL-13) in response to antigen-induced IL-25/33 and by recruiting type 2 “immune franchise.” Regarding the two different roles of type 2 cytokines, helminth expulsion and type 2-related diseases, here we review the latest advances in ILC2 biology and examine the pivotal role of resident ILCs2 in allergen-specific airway inflammation and asthma.

IL-10 production by CD4+ effector T cells: a mechanism for self-regulation

The development of Th1 lymphocytes is essential for cell-mediated immunity and resistance against intracellular pathogens. However, if left unregulated, the same response can cause serious damage to host tissues and lead to mortality. A number of different paracrine regulatory mechanisms involving distinct myeloid and lymphoid subpopulations have been implicated in controlling excessive secretion of inflammatory cytokines by Th1 cells. Much of this work has focused on interleukin (IL)-10, a cytokine with broad anti-inflammatory properties, one of which is to counteract the function of Th1 lymphocytes. While studying the role of IL-10 in regulating immunopathology during infection with the intracellular parasite Toxoplasma gondii, we discovered that the host-protective IL-10 derives in an autocrine manner from conventional interferon-gamma (IFN-gamma)-producing T-bet(+) Foxp3(neg) Th1 cells. In the following review, we will discuss these findings that support the general concept that production of IL-10 is an important self-regulatory function of CD4(+) T lymphocytes.

A Leishmania infantum cytosolic tryparedoxin activates B cells to secrete interleukin-10 and specific immunoglobulin

The immune evasion mechanisms of pathogenic trypanosomatids involve a multitude of phenomena such as the polyclonal activation of lymphocytes, cytokine modulation and the enhanced detoxification of oxygen reactive species. A trypanothione cascade seems to be involved in the detoxification process. It was recently described and characterized a tryparedoxin (LiTXN1) involved in Leishmania infantum cytoplasmatic hydroperoxide metabolism. LiTXN1 is a secreted protein that is up-regulated in the infectious form of the parasite, suggesting that it may play an important role during infection. In the present study, we investigated whether recombinant LiTXN1 (rLiTXN1) affects T- and B-cell functions in a murine model. We observed a significant increase in the CD69 surface marker on the B-cell population in total spleen cells and on isolated B cells from BALB/c mice after in vitro rLiTXN1 stimulus. Activated B-cells underwent further proliferation, as indicated by increased [(3)H]thymidine incorporation. Cytokine quantification showed a dose-dependent up-regulation of interleukin (IL)-10 secretion. B cells were identified as a source of this secretion. Furthermore, intraperitoneal injection of rLiTXN1 into BALB/c mice triggered the production of elevated levels of rLiTXN1-specific antibodies, predominantly of the immunoglobulin M (IgM), IgG1 and IgG3 isotypes, with a minimum reactivity against other heterologous antigens. Taken together, our data suggest that rLiTXN1 may participate in immunopathological processes by targeting B-cell effector functions, leading to IL-10 secretion and production of specific antibodies.

Nasal cholera toxin elicits IL-5 and IL-5 receptor alpha-chain expressing B-1a B cells for innate mucosal IgA antibody responses

In this study, we examine whether native cholera toxin (nCT) as a mucosal adjuvant can support trinitrophenyl (TNP)-LPS-specific mucosal immune responses. C57BL/6 mice were given nasal TNP-LPS in the presence or absence of nCT. Five days later, significantly higher levels of TNP-specific mucosal IgA Ab responses were induced in the nasal washes, saliva, and plasma of mice given nCT plus TNP-LPS than in those given TNP-LPS alone. High numbers of TNP-specific IgA Ab-forming cells were also detected in mucosal tissues such as the nasal passages (NPs), the submandibular glands (SMGs), and nasopharyngeal-associated lymphoreticular tissue of mice given nCT. Flow cytometric analysis showed that higher numbers of surface IgA+, CD5+ B cells (B-1a B cells) in SMGs and NPs of mice given nasal TNP-LPS plus nCT than in those given TNP-LPS alone. Furthermore, increased levels of IL-5R alpha-chain were expressed by B-1a B cells in SMGs and NPs of mice given nasal TNP-LPS plus nCT. Thus, CD4+ T cells from these mucosal effector lymphoid tissues produce high levels of IL-5 at both protein and mRNA levels. When mice were treated with anti-IL-5 mAb, significant reductions in TNP-specific mucosal IgA Ab responses were noted in external secretions. These findings show that nasal nCT as an adjuvant enhances mucosal immune responses to a T cell-independent Ag due to the cross-talk between IL-5Ralpha+ B-1a B cells and IL-5-producing CD4+ T cells in the mucosal effector lymphoid tissues.

B1 cells contribution to susceptibility in experimental paracoccidioidomycosis: immunoglobulin isotypes and repertoire determination

Paracoccidioidomycosis (PCM) is the most prevalent systemic mycosis in Latin America. The experimental murine model has been used to approach the disease, with susceptible and resistant mice strains that reproduce most of the main human immunological features. Since the hypergammaglobulinemia observed in susceptible mice and humans might have an influence on B1 cells, we investigated its role during the experimental infection with Paracoccidiodes brasiliensis. CBA/Nxid mice, deficient in B1 cells, and CBA/Nxid reconstituted with B1 cells isolated from the non-mutant CBA/J strain were infected with 106 yeast forms of P. brasiliensis. At the 8th and 22nd week post infection the DTH response of CBA/Nxid mice was significantly higher after 24 h of P. brasiliensis antigens inoculation and the specific humoral response was reduced, in comparison to CBA/J or recCBA/Nxid. Production of NAbs is a hallmark of the B1 subset. Higher Ig productions to auto antigens such as DNA, MBP and RBC were observed in CBA/J infected mice or recCBA/Nxid. Anti P. brasiliensis IgG2a was produced by CBA/Nxid mice early in infection, while CBA/J or recCBA/Nxid presented increased levels of this isotype only after the 8th week of infection. Furthermore, western blotting analysis showed that CBA/Nxid mice expanded less clones against P. brasiliensis antigens, with weakly detectable anti-gp43 antibodies while CBA/J mice produce IgM anti-gp43 at the 2nd week of infection and IgG anti-gp43 at the 2nd and 8th week. On the other hand, recognition of gp70, a fungal antigen that, as gp43, inhibits macrophage activation was not compromised in B1 deficient mice. These results suggest that B1 cells might have influence in the kinetic of production of protective isotypes of immunoglobulins and their repertoire that could contribute to an early drive towards a Th2 response, affecting the cellular response in susceptible mice during experimental paracoccidiodomycosis.

APRIL promotes B-1 cell-associated neoplasm

A tumor-supporting role for the TNF-like ligand APRIL has been suggested. Here we describe that 9- to 12-month-old APRIL transgenic mice develop lymphoid tumors that originate from expansion of the peritoneal B-1 B cell population. Aging APRIL transgenic mice develop progressive hyperplasia in mesenteric lymph nodes and Peyer's patches, disorganization of affected lymphoid tissues, mucosal and capsular infiltration, and eventual tumor cell infiltration into nonlymphoid tissues such as kidney and liver. We detected significantly increased APRIL levels in sera of B cell chronic lymphoid leukemia (B-CLL) patients, indicating that APRIL promotes onset of B-1-associated neoplasms and that APRIL antagonism may provide a therapeutic strategy to treat B-CLL patients.

The unique antigen receptor signaling phenotype of B-1 cells is influenced by locale but induced by antigen

Normal animals contain an autoreactive B lymphocyte subset, the B-1 subset, which is controlled by undefined mechanisms to prevent autoimmunity. Using a V(H)11V(kappa)9 Ig transgenic mouse, with a specificity prototypic of the subset, we have explored conditions responsible for the previously reported Ag hyporesponsiveness of these cells. We report that peritoneal V(H)11V(kappa)9 B cells exhibit typical B-1 behavior with high basal intracellular free Ca(2+) and negligible receptor-mediated calcium mobilization. However, splenic B cells from this mouse, while phenotypically similar to their peritoneal counterparts, including expression of CD5, mount robust B-2-like responses to Ag as measured by calcium influx and altered tyrosine phosphorylation responses. When these splenic cells are adoptively transferred to the peritoneal cavity and encounter their cognate self-Ag, they acquire a B-1 signaling phenotype. The ensuing hyporesponsiveness is characterized by increases in both basal intracellular calcium and resting tyrosyl phosphorylation levels and is highlighted by a marked abrogation of B cell receptor-mediated calcium mobilization. Thus, we show that self-Ag recognition in specific microenvironments such as the peritoneum, and we would propose other privileged sites, confers a unique form of anergy on activated B cells. This may explain how autoreactive B-1 cells can exist while autoimmunity is avoided.

Splenic and peritoneal B-1 cells differ in terms of transcriptional and proliferative features that separate peritoneal B-1 from splenic B-2 cells

B-1 cells constitute a distinct B cell subset with characteristic phenotypic and functional features. B-1 cells are highly represented among peritoneal lymphocytes; substantial numbers of B-1 cells are also located within splenic tissue. Here a number of differences in transcription factor and gene expression were identified that separate peritoneal B-1 and splenic B-2 cells, and then splenic B-1 cells obtained from immunoglobulin transgenic mice were tested for these parameters. Splenic B-1 cells resembled splenic B-2 cells rather than peritoneal B-1 cells in terms of nuclear expression of DNA-binding STAT3, CREB, and PU.1, with respect to transcriptional activation of IL-10, and in the failure to enter cell cycle in response to PMA. Splenic B-1 cells (B-1S) appear to constitute a unique population of B-1 cells, which, while sharing with peritoneal B-1 cells (B-1P) certain phenotypic features, differ from them in transcription factor and gene expression and in signaling for cell cycle progression.

Murine B1 B cells require IL-5 for optimal T cell-dependent activation

T helper cell-driven activation of murine B cells has been shown to depend upon CD40-CD40 ligand (CD40L) interactions and a defined set of cytokines. These observations are primarily based on the use of conventional B cells obtained from the spleen. Therefore, it is presently unclear whether all mature B cell subsets found in the mouse have an equal dependence upon CD40-CD40L interactions and use the same T cell-derived cytokines. The present study tested the response of splenic follicular and marginal zone as well as peritoneal B2 and B1 B cells to Th cell stimulation. Splenic and peritoneal B cell subsets were sort purified based on CD23 expression, and cultured with rCD40L and cytokines or Th2 cells. The results demonstrate that follicular, marginal zone, and peritoneal B2 B cells require CD40-CD40L interactions and preferentially use IL-4 for optimal proliferation, differentiation, and isotype switching. In contrast, peritoneal B1 B cells use IL-5 in conjunction with CD40-CD40L interactions for maximal Th cell-dependent responses. Furthermore, B1 B cells are capable of proliferating, differentiating, and isotype switching in the absence of CD40-CD40L interactions. B1 B cells are able to respond to Th2 clones in the presence of anti-CD40L mAb as well as to Th2 clones derived from CD40L(-/-) mice. The CD40-CD40L-independent response of B1 B cells is attributable to the presence of both IL-4 and IL-5, and may explain the residual Ab response to T cell-dependent Ags in CD40L- or CD40-deficient mice, and in X-linked hyper-IgM (X-HIM) patients.

Cytokine mRNA profiles in trypanotolerant and trypanosusceptible cattle infected with the protozoan parasite Trypanosoma congolense: protective role for interleukin-4?

African trypanosomes are important pathogens of both humans and livestock. We investigated the association of cytokine responses with disease susceptibility in Trypanosoma congolense-infected cattle. Changes in interleukin (IL)-1beta, IL-2, IL-4, IL-5, IL-6, IL-12 p40, tumor necrosis factor-alpha (TFN-alpha), CD40L, and transforming growth factor-beta (TGF-beta) gene expression were compared in peripheral blood mononuclear cells of infected trypanotolerant N'Dama (Bos taurus) and trypanosusceptible Boran (Bos indicus) cattle. Results revealed that IL-2 transcription was decreased in both breeds of cattle at 21 days after infection. IL-12 p40 mRNA expression was increased in N'Dama cattle at 21 days after infection and at a later time in Boran cattle. The highest IL-4 mRNA expression was observed at 32 days after infection in N'Dama cattle. IL-6 mRNA expression increased in Boran cattle at 11 days after infection and was elevated at 21 and 32 days after infection in both breeds. Transcripts for IL-5 were barely detectable throughout the experimental period in both Boran and N'Dama cattle. Expression of TNF-alpha, IL-1beta, and TGF-beta mRNA did not change notably during the course of infection. In summary, differences in the expression of IL-4 and IL-6 mRNA were identified between the two breeds of cattle during infection with T. congolense, suggesting a possible protective role for IL-4 and a disease-promoting role for IL-6 in bovine trypanosomosis.

Effects of intravenous immunoglobulin on plasma interleukin-10 levels in Kawasaki disease

Kawasaki disease is an acute febrile disease in children and many inflammatory cytokines are known to be involved in its pathogenesis. Interleukin-10 (IL-10) is an anti-inflammatory cytokine and previous reports have shown blood IL-10 levels were elevated during the acute phase of Kawasaki disease. In this study, we endeavoured to clarify the effects of i.v.IG on plasma IL-10 levels and to verify by RT-PCR, using specific primers, whether viral IL-10 or human IL-10 was responsible for high plasma IL-10. T-cells and B-cells were separated using magnetic beads, and IL-10 mRNA expressions were tested in both cell types. The mean plasma IL-10 levels were significantly decreased from 125.037 +/- 111.161 pg/ml, before i.v.IG treatment, to 32.437 +/- 54.716 pg/ml, after i.v.IG treatment, in subjects with Kawasaki disease. The levels of patients before i.v.IG treatment were significantly higher than those of the acute febrile patients (mean 26.956 +/- 13.316 pg/ml) and the normal controls (mean 16.042 +/- 5.088 pg/ml). RT-PCR was performed using specific primers to distinguish whether viral IL-10 (BCRF-1) or human IL-10 was produced in Kawasaki disease. Viral IL-10 (BCRF-1) mRNA expression was not detected in any groups and only human IL-10 mRNA transcripts were detected in PBMCs of Kawasaki patients as well as in those of acute febrile patients and normal controls. Human IL-10 mRNA transcripts were detected in both CD3+ T-cells and CD19+ B-cells. Elevated IL-10 levels during the acute phase of Kawasaki disease decreased immediately after i.v.IG administration, coincidentally with rapid improvement of inflammatory symptoms. Elevated plasma IL-10 in Kawasaki disease was transcripted from the human IL-10 gene and IL-10 mRNA expressions were detected in both T- and B-cells. Therefore, this study suggests that plasma IL-10 levels may be useful in the early identification and discrimination of the acute phase of Kawasaki disease from other febrile diseases. However, i.v.IG effects on IL-10 production still needs further investigation.

Altered response to and production of TGF-beta by B cells from autoimmune NZB mice

New Zealand Black (NZB) mice spontaneously develop immune dysfunction manifested as autoimmune hemolytic anemia and systemic lupus erythematosus. In later life, a subset of these mice develop clonal CD5+ B cell tumors analogous to human chronic lymphocytic leukemia (CLL). NZB disease is marked by B cell hyperactivity characterized by spontaneous immunoglobulin secretion and proliferation. Elimination of autoreactive lymphocytes by apoptosis is a vital mechanism to prevent expansion of self-reactive lymphocyte population. TGF-beta appears to be an important factor in normal and abnormal immune regulation and this cytokine may play a role in the development of chronic human B cell tumors. We asked whether the response to or production of TGF-beta by NZB B cells was aberrant and could contribute to disease development. In this study, we demonstrated that the apoptotic response to TGF-beta was increased in B cells from NZB mice compared to B cells from normal BALB/c mice. The increased apoptosis was related to endogenous activation and was possibly mediated through increased expression of the TGF-beta Type II receptor. Despite functional differences between CD5-negative B cells and CD5-positive B cells, TGF-beta induced apoptosis in both populations to a similar extent. NZB B cells also secrete increased active TGF-beta compared to BALB/c B cells. We suggest that the aberrant secretion of active TGF-beta and the increased response to the apoptotic effects of TGF-beta by NZB B cells may play a role in the disease process of these mice, perhaps attempting to limit the autoimmune phenomena, but possibly also contributing to generalized immunosuppression. We also suggest that the CD5(+) tumors in the NZB mouse may not be a fully appropriate model of human CLL, since CLL B cells are abnormally resistant to the apoptotic effects of TGF-beta.

CD5-mediated negative regulation of antigen receptor-induced growth signals in B-1 B cells

A subset of B lymphocytes present primarily in the peritoneal and pleural cavities is defined by the expression of CD5 and is elevated in autoimmune diseases. Upon signaling through membrane immunoglobulin M (mIgM), splenic B lymphocytes (B-2) proliferate, whereas peritoneal B cells (B-1) undergo apoptosis. However, in CD5-deficient mice, B-1 cells responded to mIgM crosslinking by developing a resistance to apoptosis and entering the cell cycle. In wild-type B-1 cells, prevention of association between CD5 and mIgM rescued their growth response to mIgM crosslinking. Thus the B cell receptor-mediated signaling is negatively regulated by CD5 in normal B-1 cells.

Administration of interleukin-5 or -10 activates peritoneal B-1 cells and induces autoimmune hemolytic anemia in anti-erythrocyte autoantibody-transgenic mice

Activation mechanisms of B-1 (Ly-1 B) cells have been suggested to be different from those of conventional B cells. To assess the role of various interleukins (IL) in the activation of B-1 cells, we injected IL-4, IL-5 or IL-10 into nonanemic anti-red blood cells (RBC) autoantibody-transgenic mice, in which conventional B cells are clonally deleted but peritoneal B-1 cells persist without secreting Ig. Intraperitoneal or intramuscular injection of IL-5 or IL-10, but not IL-4, increased the number of antibody-producing peritoneal B-1 cells by four- to five-fold, resulting in increased anti-RBC serum autoantibody and induction of hemolytic anemia. These results suggest that IL-5 or IL-10 may play an important role in the terminal differentiation of B-1 cells into antibody-producing cells in vivo.

Immunology of the testicular excurrent ducts

The sperm autoantigen concentration in the epididymis equals or exceeds that in the testis. This makes the epididymis a probable site of initiation of an antisperm autoimmune response. The mechanisms regulating antisperm antibody formation in the testicular excurrent ducts and some related aspects with clinical interest are reviewed.

Abnormal transcription factor induction through the surface immunoglobulin M receptor of B-1 lymphocytes

Populations of murine peritoneal B-1 and splenic B-2 cells, highly purified by negative selection techniques, were used to demonstrate that B-1 cells completely fail to enter cell cycle in response to surface immunoglobulin M (sIgM) crosslinking without any decrease in cell number or viability. This failure of B-1 cell responsiveness appears to represent a specific defect in sIgM-derived signaling inasmuch as stimulation to enter S phase occurs normally in response to activated and fixed T cells, and to lipopolysaccharide (LPS). The level at which sIgM signaling fails was determined by evaluating the nuclear expression of the transcription factor complex, NF-kappa B, whose sIgM-mediated induction in B-2 cells is dependent on protein kinase C (PKC) activation but is independent of protein synthesis. There was no induction of nuclear NF-kappa B in B-1 cells stimulated by sIgM crosslinking, although NF-kappa B was stimulated by phorbol myristate acetate and by LPS. In contrast, NF-kappa B was induced in B-2 cells by all three stimuli. Thus, in B-1 cells, the sIgM-mediated induction of a transcription factor that is substantially stimulated by anti-IgM in B-2 cells is blocked. However, all sIgM-derived signaling in B-1 cells was not impaired inasmuch as anti-IgM increased I-A antigen expression. These results strongly suggest that sIgM receptor-mediated signaling in B-1 cells is interrupted early in the signal transduction pathway, at a point proximal to the activation of PKC. These results further demonstrate that transcription factor induction can be used to analyze the level at which receptor-mediated signaling is blocked.