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Miao C, Cui Y, Li Y, Qi Q, Shang W, Chen H, Gao Y, Yuan R, Long Q, Wu W, Wang X, Yan Z, Jiang Y. Immunoinformatics Prediction and Protective Efficacy of Vaccine Candidate PiuA-PlyD4 Against Streptococcus Pneumoniae. Drug Des Devel Ther 2023; 17:3783-3801. [PMID: 38146490 PMCID: PMC10749580 DOI: 10.2147/dddt.s441302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 12/15/2023] [Indexed: 12/27/2023] Open
Abstract
Purpose This study was designed to evaluate the immune protective efficacy of the novel Streptococcus pneumoniae (S. pneumoniae) protein vaccine PiuA-PlyD4 through immunoinformatics prediction and in vitro and in vivo experiments. Methods In this study, we conducted immunoinformatics prediction and protection analysis on the fusion protein PiuA-PlyD4. The epitope composition of the vaccine was analyzed based on the prediction of B-cell and helper T-cell epitopes. Meanwhile, the molecular docking of PiuA and TLR2/4 was simulated. After immunizing C57BL/6 mice with the prepared vaccine, the biological safety, immunogenicity and conservation were evaluated. By constructing different infection models and from the aspects of adhesion inhibition and cytokines, the protective effect of the fusion protein vaccine PiuA-PlyD4 on S. pneumoniae infection was explored. Results PiuA-PlyD4 has abundant B-cell and helper T-cell epitopes and shows a high antigenicity score and structural stability. Molecular docking analysis suggested the potential interaction between PiuA and TLR2/4. The specific antibody titer of fusion protein antiserum was as high as (7.81±2.32) ×105. The protective effect of the immunized mice on nasal and lung colonization was significantly better than that of the control group, and the survival rate against S. pneumoniae infection of serotype 3 reached 50%. Cytokine detection showed that the humoral immune response, Th1, Th2 and Th17 cellular immune pathways were all involved in the process. Conclusion The study indicates that PiuA-PlyD4, whether the results are predicted by immunoinformatics or experimentally validated in vivo and in vitro, has good immunogenicity and immunoreactivity and can provide effective protection against S. pneumoniae infection. Therefore, it can be considered a promising prophylactic vaccine candidate for S. pneumoniae.
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Affiliation(s)
- Chenglin Miao
- Department of Laboratory Medicine, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China
| | - Yali Cui
- Department of Laboratory Medicine, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China
- Department of Laboratory Medicine, Meishan Women and Children’s Hospital, Alliance Hospital of West China Second University Hospital, Sichuan University, Meishan, Sichuan Province, People’s Republic of China
- Department of Laboratory Medicine, West China Second University Hospital (Tianfu), Sichuan University/Sichuan Provincial Children’s Hospital, Meishan, Sichuan Province, People’s Republic of China
| | - Yingying Li
- Department of Laboratory Medicine, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China
| | - Qianqian Qi
- Department of Laboratory Medicine, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China
| | - Wenling Shang
- Department of Laboratory Medicine, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China
| | - Huilian Chen
- Department of Laboratory Medicine, Meishan Women and Children’s Hospital, Alliance Hospital of West China Second University Hospital, Sichuan University, Meishan, Sichuan Province, People’s Republic of China
- Department of Laboratory Medicine, West China Second University Hospital (Tianfu), Sichuan University/Sichuan Provincial Children’s Hospital, Meishan, Sichuan Province, People’s Republic of China
| | - Yujie Gao
- Department of Laboratory Medicine, Meishan Women and Children’s Hospital, Alliance Hospital of West China Second University Hospital, Sichuan University, Meishan, Sichuan Province, People’s Republic of China
- Department of Laboratory Medicine, West China Second University Hospital (Tianfu), Sichuan University/Sichuan Provincial Children’s Hospital, Meishan, Sichuan Province, People’s Republic of China
| | - Ruomei Yuan
- Department of Laboratory Medicine, Meishan Women and Children’s Hospital, Alliance Hospital of West China Second University Hospital, Sichuan University, Meishan, Sichuan Province, People’s Republic of China
- Department of Laboratory Medicine, West China Second University Hospital (Tianfu), Sichuan University/Sichuan Provincial Children’s Hospital, Meishan, Sichuan Province, People’s Republic of China
| | - Qichen Long
- Department of Laboratory Medicine, The Second Xiangya Hospital, Central South University, Changsha, Hunan Province, People’s Republic of China
| | - Wenjing Wu
- Department of Laboratory Medicine, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China
| | - Xia Wang
- Department of Laboratory Medicine, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China
| | - Ziyi Yan
- Department of Laboratory Medicine, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China
| | - Yongmei Jiang
- Department of Laboratory Medicine, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, Sichuan Province, People’s Republic of China
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Daly CA, Spurrier MA, Jennings-Gee JE, Haas KM. B Cell Subsets Differentially Contribute to the T Cell-Independent Memory Pool. THE JOURNAL OF IMMUNOLOGY 2020; 205:2362-2374. [PMID: 32978280 DOI: 10.4049/jimmunol.1901453] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 08/28/2020] [Indexed: 01/27/2023]
Abstract
The roles distinct B cell subsets play in clonal expansion, isotype switching, and memory B cell differentiation in response to T cell-independent type 2 Ags (TI-2 Ags) has been understudied. Using sorted B cells from VHB1-8 knock-in mice, we evaluated B-1b, marginal zone, and follicular B cell responses to the TI-2 Ag, NP-Ficoll. All subsets extensively divided in response to NP-Ficoll. Nonetheless, B-1b cells exhibited significantly increased IgG switching and differentiation into Ab-secreting cells (ASC)-a finding that coincided with increased AgR signaling capacity and Blimp1 expression by B-1b cells. All subsets formed memory cells and expressed markers previously identified for T cell-dependent memory B cells, including CD80, PDL2, and CD73, although B-1b cells generated the greatest number of memory cells with higher frequencies of IgG- and CD80-expressing cells. Despite memory formation, secondary immunization 4 wk after primary immunization did not increase NP-specific IgG. However, boosting occurred in B-1b cell-recipient mice when IgG levels declined. CD80+ memory B-1b cells divided, class switched, and differentiated into ASC in response to Ag in vivo, but this was inhibited in the presence of NP-specific IgG. Furthermore, CD80 blockade significantly increased memory B-1b cell division and differentiation to ASC upon Ag restimulation. Collectively, these findings demonstrate B-1b, marginal zone B, and follicular B subsets significantly contribute to the TI-2 Ag-specific memory B cell pool. In particular, we show B-1b cells generate a functional CD80-regulated memory population that can be stimulated to divide and differentiate into ASC upon Ag re-encounter when Ag-specific IgG levels decline.
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Affiliation(s)
- Christina A Daly
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC 27157
| | - M Ariel Spurrier
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC 27157
| | - Jamie E Jennings-Gee
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC 27157
| | - Karen M Haas
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC 27157
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Jaufmann J, Tümen L, Schmitt F, Schäll D, von Holleben M, Beer-Hammer S. SLy2-deficiency promotes B-1 cell immunity and triggers enhanced production of IgM and IgG 2 antibodies against pneumococcal vaccine. IMMUNITY INFLAMMATION AND DISEASE 2020; 8:736-752. [PMID: 33098380 PMCID: PMC7654406 DOI: 10.1002/iid3.365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/15/2020] [Accepted: 10/13/2020] [Indexed: 01/01/2023]
Abstract
Background Despite the benefits of existing vaccines, Streptococcus pneumoniae is still responsible for the greatest proportion of respiratory tract infections around the globe, thereby substantially contributing to morbidity and mortality in humans. B‐1 cells are key players of bacterial clearance during pneumococcal infection and even provide long‐lasting immunity towards S. pneumoniae. Previous reports strongly suggest an essential role of the immunoinhibitory adapter Src homology domain 3 lymphocyte protein 2 (SLy2) for B‐1 cell‐mediated antibody production. The objective of this study is to evaluate S. pneumoniae‐directed B cell responses in the context of SLy2 deficiency. Methods B‐1 cell populations were analyzed via flow cytometry before and after pneumococcal immunization of SLy2‐deficient and wild‐type control mice. Global and vaccine‐specific immunoglobulin M (IgM) and IgG antibody titers were assessed by enzyme‐linked immunosorbent assay. To investigate survival rates during acute pneumococcal lung infection, mice were intranasally challenged with S. pneumoniae (serotype 3). Complementary isolated splenic B cells were stimulated in vitro and their proliferative response was assessed by fluorescent staining. In vitro antibody secretion was quantified by LEGENDplex. Results We demonstrate increased frequencies of B‐1 cells and elevated titers of preantigenic IgM in SLy2‐deficient mice. In addition, these mice produce significantly more amounts of IgM and IgG2 upon pneumococcal vaccination. Knocking out SLy2 did not induce survival advantages in our murine model of acute pneumonia, indicating the presence of compensatory mechanisms. Conclusion Our results reveal reinforced specific antibody responses towards pneumococcal polysaccharides and enhanced IgG2 secretion as a consequence of SLy2 deficiency, which could be relevant to the development of more efficient vaccines.
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Affiliation(s)
- Jennifer Jaufmann
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomik and ICePhA, University of Tuebingen, Tuebingen, Germany
| | - Leyla Tümen
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomik and ICePhA, University of Tuebingen, Tuebingen, Germany
| | - Fee Schmitt
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomik and ICePhA, University of Tuebingen, Tuebingen, Germany
| | - Daniel Schäll
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomik and ICePhA, University of Tuebingen, Tuebingen, Germany
| | - Max von Holleben
- Institute for Medical Microbiology and Hospital Hygiene, Heinrich-Heine-University, Duesseldorf, Germany
| | - Sandra Beer-Hammer
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomik and ICePhA, University of Tuebingen, Tuebingen, Germany.,Institute for Medical Microbiology and Hospital Hygiene, Heinrich-Heine-University, Duesseldorf, Germany
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Savage HP, Yenson VM, Sawhney SS, Mousseau BJ, Lund FE, Baumgarth N. Blimp-1-dependent and -independent natural antibody production by B-1 and B-1-derived plasma cells. J Exp Med 2017; 214:2777-2794. [PMID: 28698287 PMCID: PMC5584113 DOI: 10.1084/jem.20161122] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 04/27/2017] [Accepted: 06/08/2017] [Indexed: 11/04/2022] Open
Abstract
Natural antibodies contribute to tissue homeostasis and protect against infections. They are secreted constitutively without external antigenic stimulation. The differentiation state and regulatory pathways that enable continuous natural antibody production by B-1 cells, the main cellular source in mice, remain incompletely understood. Here we demonstrate that natural IgM-secreting B-1 cells in the spleen and bone marrow are heterogeneous, consisting of (a) terminally differentiated B-1-derived plasma cells expressing the transcriptional regulator of differentiation, Blimp-1, (b) Blimp-1+, and (c) Blimp-1neg phenotypic B-1 cells. Blimp-1neg IgM-secreting B-1 cells are not simply intermediates of cellular differentiation. Instead, they secrete similar amounts of IgM in wild-type and Blimp-1-deficient (PRDM-1ΔEx1A) mice. Blimp-1neg B-1 cells are also a major source of IgG3. Consequently, deletion of Blimp-1 changes neither serum IgG3 levels nor the amount of IgG3 secreted per cell. Thus, the pool of natural antibody-secreting B-1 cells is heterogeneous and contains a distinct subset of cells that do not use Blimp-1 for initiation or maximal antibody secretion.
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Affiliation(s)
- Hannah P Savage
- Graduate Group in Immunology, University of California, Davis, Davis, CA.,Center for Comparative Medicine, University of California, Davis, Davis, CA
| | - Vanessa M Yenson
- Center for Comparative Medicine, University of California, Davis, Davis, CA
| | - Sanjam S Sawhney
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, CA
| | - Betty J Mousseau
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL
| | - Frances E Lund
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL
| | - Nicole Baumgarth
- Graduate Group in Immunology, University of California, Davis, Davis, CA .,Center for Comparative Medicine, University of California, Davis, Davis, CA.,Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, CA
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Increased NHC Cells in the Peritoneal Cavity of Plasmacytoma Susceptible BALB/c Mouse. Mediators Inflamm 2015; 2015:313140. [PMID: 26504358 PMCID: PMC4609491 DOI: 10.1155/2015/313140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Accepted: 01/05/2015] [Indexed: 11/18/2022] Open
Abstract
BALB/c strain mice are unique in that they develop murine plasmacytoma (MPC) as a consequence of the inflammation induced by pristane oil injection in the peritoneal cavity. In this work the Treg, Th17, B1, B2, and NHC lymphocyte populations from the peritoneal environment of BALB/c, the susceptible strain, and C57BL/6 mice, which do not develop MPC after oil treatment, were studied. Both oil-treated strains showed decreased levels of Th17 lymphocytes, no significant variation in Treg lymphocytes, and a drastic decrease of all B lymphocyte populations. However, only oil-induced BALB/c showed increased levels of natural helper cells (NHC) which could be important in the myeloma induction.
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Yang Q, Lai SK. Anti-PEG immunity: emergence, characteristics, and unaddressed questions. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2015; 7:655-77. [PMID: 25707913 DOI: 10.1002/wnan.1339] [Citation(s) in RCA: 373] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 01/07/2015] [Accepted: 01/18/2015] [Indexed: 12/22/2022]
Abstract
The modification of protein and nanoparticle therapeutics with polyethylene glycol (PEG), a flexible, uncharged, and highly hydrophilic polymer, is a widely adopted approach to reduce RES clearance, extend circulation time, and improve drug efficacy. Nevertheless, an emerging body of literature, generated by numerous research groups, demonstrates that the immune system can produce antibodies that specifically bind PEG, which can lead to the 'accelerated blood clearance' of PEGylated therapeutics. In animals, anti-PEG immunity is typically robust but short-lived and consists of a predominantly anti-PEG IgM response. Rodent studies suggest that the induction of anti-PEG antibodies (α-PEG Abs) primarily occurs through a type 2 T-cell independent mechanism. Although anti-PEG immunity is less well-studied in humans, the presence of α-PEG Abs has been correlated with reduced efficacy of PEGylated therapeutics in clinical trials. The prevalence of anti-PEG IgG and reports of memory immune responses, as well as the existence of α-PEG Abs in healthy untreated individuals, suggests that the mechanism(s) and features of human anti-PEG immune responses may differ from those of animal models. Many questions, including the incidence rate of pre-existing α-PEG Abs and immunological mechanism(s) of α-PEG Ab formation in humans, must be answered in order to fully address the potential complications of anti-PEG immunity.
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Affiliation(s)
- Qi Yang
- Division of Molecular Pharmaceutics, University of North Carolina, Chapel Hill, NC, USA
| | - Samuel K Lai
- Division of Molecular Pharmaceutics, University of North Carolina, Chapel Hill, NC, USA.,UNC/NCSU Joint Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA
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Cunningham AF, Flores-Langarica A, Bobat S, Dominguez Medina CC, Cook CNL, Ross EA, Lopez-Macias C, Henderson IR. B1b cells recognize protective antigens after natural infection and vaccination. Front Immunol 2014; 5:535. [PMID: 25400633 PMCID: PMC4215630 DOI: 10.3389/fimmu.2014.00535] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 10/10/2014] [Indexed: 12/18/2022] Open
Abstract
There are multiple, distinct B-cell populations in human beings and other animals such as mice. In the latter species, there is a well-characterized subset of B-cells known as B1 cells, which are enriched in peripheral sites such as the peritoneal cavity but are rare in the blood. B1 cells can be further subdivided into B1a and B1b subsets. There may be additional B1 subsets, though it is unclear if these are distinct populations or stages in the developmental process to become mature B1a and B1b cells. A limitation in understanding B1 subsets is the relative paucity of specific surface markers. In contrast to mice, the existence of B1 cells in human beings is controversial and more studies are needed to investigate the nature of these enigmatic cells. Examples of B1b antigens include pneumococcal polysaccharide and the Vi antigen from Salmonella Typhi, both used routinely as vaccines in human beings and experimental antigens such as haptenated-Ficoll. In addition to inducing classical T-dependent responses some proteins are B1b antigens and can induce T-independent (TI) immunity, examples include factor H binding protein from Borrelia hermsii and porins from Salmonella. Therefore, B1b antigens can be proteinaceous or non-proteinaceous, induce TI responses, memory, and immunity, they exist in a diverse range of pathogenic bacteria, and a single species can contain multiple B1b antigens. An unexpected benefit to studying B1b cells is that they appear to have a propensity to recognize protective antigens in bacteria. This suggests that studying B1b cells may be rewarding for vaccine design as immunoprophylactic and immunotherapeutic interventions become more important due to the decreasing efficacy of small molecule antimicrobials.
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Affiliation(s)
- Adam F Cunningham
- MRC Centre for Immune Regulation, Institute for Microbiology and Infection, School of Immunity and Infection, Institute for Biomedical Research, Medical School, University of Birmingham , Birmingham , UK
| | - Adriana Flores-Langarica
- MRC Centre for Immune Regulation, Institute for Microbiology and Infection, School of Immunity and Infection, Institute for Biomedical Research, Medical School, University of Birmingham , Birmingham , UK
| | - Saeeda Bobat
- MRC Centre for Immune Regulation, Institute for Microbiology and Infection, School of Immunity and Infection, Institute for Biomedical Research, Medical School, University of Birmingham , Birmingham , UK
| | - Carmen C Dominguez Medina
- MRC Centre for Immune Regulation, Institute for Microbiology and Infection, School of Immunity and Infection, Institute for Biomedical Research, Medical School, University of Birmingham , Birmingham , UK
| | - Charlotte N L Cook
- MRC Centre for Immune Regulation, Institute for Microbiology and Infection, School of Immunity and Infection, Institute for Biomedical Research, Medical School, University of Birmingham , Birmingham , UK
| | - Ewan A Ross
- MRC Centre for Immune Regulation, Institute for Microbiology and Infection, School of Immunity and Infection, Institute for Biomedical Research, Medical School, University of Birmingham , Birmingham , UK
| | - Constantino Lopez-Macias
- Medical Research Unit on Immunochemistry, National Medical Centre "Siglo XXI", Specialties Hospital, Mexican Institute for Social Security (IMSS) , Mexico City , Mexico
| | - Ian R Henderson
- MRC Centre for Immune Regulation, Institute for Microbiology and Infection, School of Immunity and Infection, Institute for Biomedical Research, Medical School, University of Birmingham , Birmingham , UK
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Efficient B cell responses to Borrelia hermsii infection depend on BAFF and BAFFR but not TACI. Infect Immun 2013; 82:453-9. [PMID: 24218480 DOI: 10.1128/iai.01147-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
T cell-independent antibody responses develop rapidly, within 3 to 4 days, and are critical for preventing blood-borne pathogens from evolving into life-threatening infections. The interaction of BAFF, also known as BLyS, with its receptors BAFFR and TACI on B cells is critical for B cell homeostasis and function. Using a synthetic polysaccharide antigen, it has previously been shown that TACI is critical for T cell-independent antibody responses. To examine the role of BAFFR and TACI in T cell-independent antibody responses to an active infection, we utilized the Borrelia hermsii infection system. In this infection system, T cell-independent responses mediated by the B1b cell subset are critical for controlling bacteremia. We found that B1b cells express BAFFR and TACI and that the surface expression of both receptors is upregulated on B1b cells following exposure to whole B. hermsii cells. Surprisingly, we found that TACI(-/-) mice are not impaired either in specific antibody responses to B. hermsii or in controlling B. hermsii bacteremia. In contrast, TACI-deficient mice immunized with heat-killed type 3 serotype pneumococcus cells are impaired in generating pneumococcal polysaccharide-specific responses and succumb to challenge with live type 3 serotype pneumococcus, indicating that TACI is required for T cell-independent antibody responses to bacterial-associated polysaccharides. Although we have found that TACI is dispensable for controlling B. hermsii infection, mice deficient in BAFFR or BAFF exhibit impairment in B. hermsii-specific IgM responses and clearance of bacteremia. Collectively, these data indicate a disparity in the roles for TACI and BAFFR in primary T cell-independent antibody responses to bacterial pathogens.
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Kaveri SV, Silverman GJ, Bayry J. Natural IgM in immune equilibrium and harnessing their therapeutic potential. THE JOURNAL OF IMMUNOLOGY 2012; 188:939-45. [PMID: 22262757 DOI: 10.4049/jimmunol.1102107] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Natural IgM Abs are the constitutively secreted products of B1 cells (CD5(+) in mice and CD20(+)CD27(+)CD43(+)CD70(-) in humans) that have important and diverse roles in health and disease. Whereas the role of natural IgM as the first line of defense for protection against invading microbes has been extensively investigated, more recent reports have highlighted their potential roles in the maintenance of tissue homeostasis via clearance of apoptotic and altered cells through complement-dependent mechanisms, inhibition of inflammation, removal of misfolded proteins, and regulation of pathogenic autoreactive IgG Abs and autoantibody-producing B cells. These observations have provided the theoretical underpinnings for efforts that currently seek to harness the untapped therapeutic potential of natural IgM either by boosting in vivo natural IgM production or via therapeutic infusions of monoclonal and polyclonal IgM preparations.
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