RESUMEN
Circulating follicular helper T cells (cTfh) can show phenotypic alterations in disease settings, including in the context of tissue-damaging autoimmune or anti-viral responses. Using severe COVID-19 as a paradigm of immune dysregulation, we have explored how cTfh phenotype relates to the titre and quality of antibody responses. Severe disease was associated with higher titres of neutralising S1 IgG and evidence of increased T cell activation. ICOS, CD38 and HLA-DR expressing cTfh correlated with serum S1 IgG titres and neutralising strength, and interestingly expression of TIGIT by cTfh showed a negative correlation. TIGIT+cTfh expressed increased IFNγ and decreased IL-17 compared to their TIGIT-cTfh counterparts, and showed reduced capacity to help B cells in vitro. Additionally, TIGIT+cTfh expressed lower levels of CD40L than TIGIT-cTfh, providing a potential explanation for their poor B-helper function. These data identify phenotypic changes in polyclonal cTfh that correlate with specific antibody responses and reveal TIGIT as a marker of cTfh with altered function.
Asunto(s)
Anticuerpos Antivirales , Linfocitos B , COVID-19 , Receptores Inmunológicos , SARS-CoV-2 , Células T Auxiliares Foliculares , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Anticuerpos Neutralizantes/inmunología , Anticuerpos Neutralizantes/sangre , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Linfocitos B/inmunología , COVID-19/inmunología , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunología , Activación de Linfocitos/inmunología , Receptores Inmunológicos/inmunología , SARS-CoV-2/inmunología , Células T Auxiliares Foliculares/inmunología , Anciano de 80 o más AñosRESUMEN
The B cell "help" function of CD4+ T cells is an important mechanism of adaptive immunity. Here, we describe improved antigen-specific T-B cocultures for quantitative measurement of T cell-dependent B cell responses, with as few as â¼90 T cells. Utilizing M. tuberculosis (Mtb), we show that early priming and activation of CD4+ T cells is important for productive interaction between T and B cells and that similar effects are achieved by supplementing cocultures with monocytes. We find that monocytes promote survivability of B cells via BAFF and stem cell growth factor (SCGF)/C-type lectin domain family 11 member A (CLEC11A), but this alone does not fully recapitulate the effects of monocyte supplementation. Importantly, we demonstrate improved activation and immunological output of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific memory CD4+ T-B cell cocultures with the inclusion of monocytes. This method may therefore provide a more sensitive assay to evaluate the B cell help quality of memory CD4+ T cells, for example, after vaccination or natural infection.
Asunto(s)
Linfocitos B , Linfocitos T CD4-Positivos , COVID-19 , Memoria Inmunológica , Humanos , Linfocitos T CD4-Positivos/inmunología , COVID-19/inmunología , Mycobacterium tuberculosis , SARS-CoV-2 , Linfocitos B/inmunología , InmunoensayoRESUMEN
The relationship between B cells and CD4 T cells has been carefully studied, revealing a collaborative effort in which B cells promote the activation, differentiation, and expansion of CD4 T cells while the so-called "helper" cells provide signals to B cells, influencing their class switching and fate. Interactions between B cells and CD8 T cells are not as well studied, although CD8 T cells exhibit an accelerated contraction after certain infections in B-cell-deficient mice. Here, we find that B cells significantly enhance primary CD8 T cell responses after vaccination. Moreover, memory CD8 numbers and function are impaired in B-cell-deficient animals, leading to increased susceptibility to bacterial challenge. We also show that interleukin-27 production by B cells contributes to their impact on primary, but not memory, CD8 responses. Better understanding of the interactions between CD8 T cells and B cells may aid in the design of more effective future vaccine strategies.
Asunto(s)
Linfocitos B/inmunología , Linfocitos T CD8-positivos/inmunología , Memoria Inmunológica , Interleucina-27/inmunología , Interleucina-27/metabolismo , Linfocitos T Colaboradores-Inductores/inmunología , Vacunas de Subunidad/inmunología , Animales , Linfocitos B/metabolismo , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , COVID-19/inmunología , Humanos , Recuento de Linfocitos , Ratones , Ratones Endogámicos C57BL , Receptores Virales/inmunología , SARS-CoV-2/inmunología , Glicoproteína de la Espiga del Coronavirus/inmunología , VacunaciónRESUMEN
Vaccine strategies targeting the mucosal portal of entry may prevent HIV acquisition and systemic infection. Macrophages in cervicovaginal compartments are one of the first cell types to encounter virus upon vaginal exposure. Their activation can lead to recruitment of additional macrophages and CD4+ T-cells susceptible to viral infection. However, they are also critical in providing early protection against invading pathogens. Therefore, understanding their response to immunization is important for vaccine design. We immunized rhesus macaques twice mucosally with replicating adenovirus (Ad) SIV recombinants, followed by two intramuscular boosts with SIV gp120 protein. Macaques were subsequently challenged intravaginally with repeated low doses of SIVmac251. Using flow cytometry, we evaluated responses of cervicovaginal macrophages (CVM) and alveolar macrophages (AM) in bronchoalveolar lavage as initial immunization was to the upper respiratory tract. The frequency of CVM increased over the course of immunization; however, CCR5 expression significantly decreased. Significantly increased expression of the chemokines CCL3 (p < 0.01), CCL4, CCL5, and CXCL8 (p < 0.0001 for all) on CVM was seen post-1st Ad but their expression significantly decreased post-2nd boost. CD4+ T-cell frequency in the cervical mucosa remained unchanged. CVM FcγRIII expression was significantly increased at all time points post-immunization compared to naïve animals. FcγRIII expression post-2nd Ad positively correlated with the number of challenges needed for infection (r = 0.68; p = 0.0051). Vaccination increased AM FcγRIII expression which post-2nd boost correlated with antibody-dependent phagocytosis. Activation of AMs was evident by increased expression of CD40 and CD80 post-2nd Ad compared to naïve macaques. APRIL expression also significantly increased post-2nd Ad and correlated with B cell frequency in bronchoalveolar lavage (BAL) (r = 0.73; p = 0.0019) and total IgG in BAL-fluid (r = 0.53; p = 0.047). B cells cultured with SIV gp120-stimulated AM supernatant from vaccinated macaques exhibited significant increases in B cell activation markers CD38 and CD69 compared to B cells cultured alone or with AM supernatant from unvaccinated macaques. Overall, the vaccine regimen did not induce recruitment of susceptible cells to the vaginal mucosa but increased CVM FcγRIII expression which correlated with delayed SIV acquisition. Further, immunization induced expression of AM cytokines, including those associated with providing B cell help.
Asunto(s)
Vacunas contra el SIDA/inmunología , Linfocitos B/inmunología , Cuello del Útero/inmunología , Infecciones por VIH/inmunología , VIH-1/fisiología , Macrófagos Alveolares/inmunología , Glicoproteínas de Membrana/inmunología , Membrana Mucosa/inmunología , Vacunas contra el SIDAS/inmunología , Síndrome de Inmunodeficiencia Adquirida del Simio/inmunología , Virus de la Inmunodeficiencia de los Simios/fisiología , Vagina/inmunología , Proteínas del Envoltorio Viral/inmunología , Adenoviridae/genética , Animales , Anticuerpos Antivirales/metabolismo , Citocinas/metabolismo , Resistencia a la Enfermedad , Femenino , Humanos , Inmunización Secundaria , Macaca mulatta , Vacunas SintéticasRESUMEN
Interleukin 10 (IL-10) is an antiinflammatory cytokine, but also promotes B cell responses and plays a pathogenic role in systemic lupus erythematosus (SLE). CD4+CCR6+IL-7R+T cells from human tonsils produced IL-10 following stimulation by naïve B cells, which promoted B cell immunoglobulin G (IgG) production. These tonsillar CCR6+B helper T cells were phenotypically distinct from follicular helper T (TFH) cells and lacked BCL6 expression. In peripheral blood, a CCR6+T cell population with similar characteristics was identified, which lacked Th17- and TFH-associated gene signatures and differentiation-associated surface markers. CD4+CCR6+T cells expressing IL-10, but not IL-17, were also detectable in the spleens of cytokine reporter mice. They provided help for IgG production in vivo, and expanded systemically in pristane-induced lupus-like disease. In SLE patients, CD4+CCR6+IL-7R+T cells were associated with the presence of pathogenic anti-dsDNA (double-stranded DNA) antibodies, and provided spontaneous help for autoantibody production ex vivo. Strikingly, IL-10-producing CCR6+T cells were highly abundant in lymph nodes of SLE patients, and colocalized with B cells at the margins of follicles. In conclusion, we identified a previously uncharacterized population of extrafollicular B helper T cells, which produced IL-10 and could play a prominent pathogenic role in SLE.
Asunto(s)
Linfocitos B/inmunología , Interleucina-10/inmunología , Lupus Eritematoso Sistémico/inmunología , Receptores CCR6/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Adulto , Animales , Formación de Anticuerpos , Niño , Citocinas/inmunología , Humanos , Interleucina-10/biosíntesis , Interleucina-17/metabolismo , Lupus Eritematoso Sistémico/metabolismo , Ratones , Ratones Endogámicos C57BL , Tonsila Palatina/citología , Tonsila Palatina/inmunología , Receptores CCR6/biosíntesis , Células Th17/inmunologíaRESUMEN
T follicular helper (TFH) cells are pivotal in lymph node (LN) germinal center (GC) B cell affinity maturation. Circulating CXCR5+ CD4+ T (cTFH) cells have supported memory B cell activation and broadly neutralizing antibodies in HIV controllers. We investigated the contribution of LN SIV-specific TFH and cTFH cells to Env-specific humoral immunity in female rhesus macaques following a mucosal Ad5hr-SIV recombinant priming and SIV gp120 intramuscular boosting vaccine regimen and following SIV vaginal challenge. TFH and B cells were characterized by flow cytometry. B cell help was evaluated in TFH-B cell co-cultures and by real-time PCR. Vaccination induced Env-specific TFH and Env-specific memory (ESM) B cells in LNs. LN Env-specific TFH cells post-priming and GC ESM B cells post-boosting correlated with rectal Env-specific IgA titers, and GC B cells at the same timepoints correlated with vaginal Env-specific IgG titers. Vaccination expanded cTFH cell responses, including CD25+ Env-specific cTFH cells that correlated negatively with vaginal Env-specific IgG titers but positively with rectal Env-specific IgA titers. Although cTFH cells post-2nd boost positively correlated with viral-loads following SIV challenge, cTFH cells of SIV-infected and protected macaques supported maturation of circulating B cells into plasma cells and IgA release in co-culture. Additionally, cTFH cells of naïve macaques promoted upregulation of genes associated with B cell proliferation, BCR engagement, plasma cell maturation, and antibody production, highlighting the role of cTFH cells in blood B cell maturation. Vaccine-induced LN TFH and GC B cells supported anti-viral mucosal immunity while cTFH cells provided B cell help in the periphery during immunization and after SIV challenge. Induction of TFH responses in blood and secondary lymphoid organs is likely desirable for protective efficacy of HIV vaccines.
Asunto(s)
Inmunidad Humoral , Inmunidad Mucosa , Inmunogenicidad Vacunal , Glicoproteínas de Membrana/administración & dosificación , Vacunas contra el SIDAS/administración & dosificación , Virus de la Inmunodeficiencia de los Simios/inmunología , Células T Auxiliares Foliculares/inmunología , Vacunación , Proteínas del Envoltorio Viral/administración & dosificación , Animales , Linfocitos B/inmunología , Linfocitos B/metabolismo , Linfocitos B/virología , Células Cultivadas , Técnicas de Cocultivo , Femenino , Memoria Inmunológica , Macaca mulatta , Glicoproteínas de Membrana/inmunología , Recto , Vacunas contra el SIDAS/inmunología , Células T Auxiliares Foliculares/metabolismo , Células T Auxiliares Foliculares/virología , Vagina , Proteínas del Envoltorio Viral/inmunologíaRESUMEN
Mucosal-associated invariant T (MAIT) cells are an innate-like T cell subset, restricted by the nonclassic MHC class I-related protein MR1 and enriched at mucosal sites. Human studies have shown an association between MAIT cells and pathogen-specific antibody responses. In this study, we investigate the effect of human MAIT cells on B cells ex vivo. We found that supernatants from microbe- or cytokine-stimulated MAIT cells, when added to purified autologous B cells, increase frequencies of plasmablasts and promote IgA, IgG, and IgM production. We found effects to be mostly MR1-dependent and that the increases in plasmablasts are likely a result of increased differentiation from memory B cells. Furthermore, microbe-activated MAIT cell supernatant contains multiple cytokines known to stimulate B cells, including IL-6, -10, and -21. This study thus provides the first direct evidence of a newly identified role of MAIT cells in providing help to B cells.
Asunto(s)
Linfocitos B/inmunología , Comunicación Celular/inmunología , Regulación de la Expresión Génica/inmunología , Antígenos de Histocompatibilidad Clase I/inmunología , Inmunidad Mucosa , Antígenos de Histocompatibilidad Menor/inmunología , Células T Invariantes Asociadas a Mucosa/inmunología , Linfocitos B/citología , Separación Celular , Técnicas de Cocultivo , Escherichia coli/química , Escherichia coli/efectos de los fármacos , Escherichia coli/inmunología , Formaldehído/química , Formaldehído/toxicidad , Expresión Génica , Antígenos de Histocompatibilidad Clase I/genética , Humanos , Inmunoglobulina A/biosíntesis , Inmunoglobulina G/biosíntesis , Inmunoglobulina M/biosíntesis , Memoria Inmunológica , Interferón gamma/genética , Interferón gamma/inmunología , Interleucina-10/genética , Interleucina-10/inmunología , Interleucina-6/genética , Interleucina-6/inmunología , Interleucinas/genética , Interleucinas/inmunología , Activación de Linfocitos , Antígenos de Histocompatibilidad Menor/genética , Células T Invariantes Asociadas a Mucosa/citología , Polímeros/química , Polímeros/toxicidad , Cultivo Primario de Células , Transducción de Señal , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/inmunologíaRESUMEN
T follicular helper (Tfh) cells are a subset of effector CD4(+) T cells specialised to induce Ab production by B cells. This review highlights some of the recent advances in the field of human Tfh cells that have come from the study of primary immunodeficiencies. In particular it is increasingly evident that the quality of the Tfh cells that are generated, is just as important as the quantity.
Asunto(s)
Susceptibilidad a Enfermedades , Síndromes de Inmunodeficiencia/etiología , Síndromes de Inmunodeficiencia/metabolismo , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismo , Linfocitos T Colaboradores-Inductores/inmunología , Linfocitos T Colaboradores-Inductores/metabolismo , Biomarcadores , Citocinas/metabolismo , Regulación de la Expresión Génica , Humanos , Fenotipo , Receptores de Citocinas/metabolismo , Transducción de Señal , Factores de Transcripción/metabolismoRESUMEN
T follicular helper (Tfh) cells are essential providers of help to B cells. The transcription factor B-cell CLL/lymphoma 6 (Bcl6) is a lineage-defining regulator of Tfh cells and germinal center B cells. In B cells, Bcl6 has the potential to recruit distinct transcriptional corepressors through its BTB domain or its poorly characterized middle domain (also known as RDII), but in Tfh cells the roles of the Bcl6 middle domain have yet to be clarified. Mimicked acetylation of the Bcl6 middle domain (K379Q) in CD4 T cells results in significant reductions in Tfh differentiation in vivo. Blimp1 (Prdm1) is a potent inhibitor of Tfh cell differentiation. Although Bcl6 K379Q still bound to the Prdm1 cis-regulatory elements in Tfh cells, Prdm1 expression was derepressed. This was a result of the failure of Bcl6 K379Q to recruit metastasis-associated protein 3 (MTA3). The loss of Bcl6 function in Bcl6 K379Q-expressing CD4 T cells could be partially rescued by abrogating Prdm1 expression. In addition to Prdm1, we found that Bcl6 recruits MTA3 to multiple genes involved in Tfh cell biology, including genes important for cell migration, cell survival, and alternative differentiation pathways. Thus, Bcl6 middle domain mediated repression is a major mechanism of action by which Bcl6 controls CD4 T-cell fate and function.
Asunto(s)
Diferenciación Celular/inmunología , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/inmunología , Proteínas de Neoplasias/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Animales , Inmunoprecipitación de Cromatina , Clonación Molecular , Cartilla de ADN/genética , Citometría de Flujo , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Mutagénesis Sitio-Dirigida , Proteínas de Neoplasias/genética , Factor 1 de Unión al Dominio 1 de Regulación Positiva , Estructura Terciaria de Proteína , Proteínas Proto-Oncogénicas c-bcl-6 , Reacción en Cadena en Tiempo Real de la Polimerasa , Proteínas Represoras/inmunología , Factores de Transcripción/metabolismoRESUMEN
T-cell help to B lymphocytes is one of the most important events in adaptive immune responses in health and disease. It is generally delivered by cognate CD4(+) T follicular helper (T(FH)) cells via both cell-to-cell contacts and soluble mediators, and it is essential for both the clonal expansion of antibody (Ab)-secreting B cells and memory B-cell formation. CD1d-restricted invariant natural killer T (iNKT) cells are a subset of innate-like T lymphocytes that rapidly respond to stimulation with specific lipid antigens (Ags) that are derived from infectious pathogens or stressed host cells. Activated iNKT cells produce a wide range of cytokines and upregulate costimulatory molecules that can promote activation of dendritic cells (DCs), natural killer (NK) cells, and T cells. A decade ago, we discovered that iNKT cells can help B cells to proliferate and to produce IgG Abs in vitro and in vivo. This adjuvant-like function of Ag-activated iNKT cells provides a flexible set of helper mechanisms that expand the current paradigm of T-cell-B-cell interaction and highlights the potential of iNKT-cell targeting vaccine formulations.
Asunto(s)
Inmunidad Adaptativa/inmunología , Linfocitos B/inmunología , Inmunidad Innata/inmunología , Células T Asesinas Naturales/inmunología , Animales , Antígenos/inmunología , Citocinas/inmunología , HumanosRESUMEN
Although many relevant immune reactions are initiated in the lymph nodes, this compartment has not been systematically studied in humans. Analyses have been performed on immune cells derived from tonsils, but as this tissue is most often inflamed, generalization of these data is difficult. Here, we analyzed the phenotype and function of the human CD4(+) T-cell subsets and lineages in paired resting lymph node and peripheral blood samples. Naive, central memory cells and effector memory cells as well as Th1, Th2, Th17 and Treg cells were equally represented in both compartments. On the other hand, cytotoxic CD4(+) T cells were strikingly absent in the lymph nodes. CXCR5(+)CD4(+) T cells, representing putative follicular Th (Tfh) cells were over-represented in lymph nodes and expressed higher levels of Tfh markers than their peripheral blood counterparts. Compared with the circulating pool, lymph-node-derived CXCR5(+)CD4(+) T cells were superior in providing help to B cells. Thus, functionally competent Tfh cells accumulate in resting human lymph nodes, providing a swift induction of naive and memory antibody responses upon antigenic challenge.