RESUMEN
Rheumatoid arthritis occurs most often in people who express HLA-DR molecules containing a five aa "shared epitope" in the ß chain. These MHCII molecules preferentially bind citrullinated peptides formed by posttranslational modification of arginine. Citrullinated peptide:HLA-DR complexes may act as arthritis-initiating neo-antigens for CD4+ T cells. Here, we used fluorophore-conjugated HLA-DR tetramers containing citrullinated peptides from human cartilage intermediate layer protein, fibrinogen, vimentin, or enolase 1 to track cognate CD4+ T cells. Immunization of HLA-DR transgenic mice with citrullinated peptides from vimentin or enolase 1 failed to cause any expansion of tetramer-binding cells, whereas immunization with citrullinated peptides from cartilage intermediate layer protein or fibrinogen elicited some expansion. The expanded tetramer-binding populations, however, had lower T helper 1 and higher regulatory T cell frequencies than populations elicited by viral peptides. These results indicate that HLA-DR-bound citrullinated peptides are not neo-antigens and induce varying degrees of immune tolerance that could pose a barrier to rheumatoid arthritis.
Asunto(s)
Artritis Reumatoide , Linfocitos T CD4-Positivos , Tolerancia Inmunológica , Animales , Humanos , Ratones , Fibrinógeno , Antígenos HLA-DR , Ratones Transgénicos , Péptidos , Péptidos Cíclicos , Fosfopiruvato Hidratasa/metabolismo , Vimentina/química , CitrulinaciónRESUMEN
In the past few decades, a number of transformative discoveries have been made regarding memory CD8+ T cell biology; meanwhile, the CD4+ T cell field has lagged behind this progress. This perspective focuses on CD4+ helper T (Th) cell subset specification and memory cell formation. Here, we argue that the sheer number of Th effector and memory cell subsets and a focus on their differences have been a barrier to a general model of CD4+ memory T cell formation that applies to all immune responses. We highlight a bifurcation model that relies on an IL-2 signal-dependent switch as an explanation for the balanced production of diverse Th memory cells that participate in cell-mediated or humoral immunity in most contexts.
Asunto(s)
Linfocitos T CD4-Positivos , Subgrupos de Linfocitos T , Linfocitos T Colaboradores-Inductores , Linfocitos T CD8-positivos , Memoria InmunológicaRESUMEN
Respiratory tract resident memory T cells (TRM), typically generated by local vaccination or infection, can accelerate control of pulmonary infections that evade neutralizing antibody. It is unknown whether mRNA vaccination establishes respiratory TRM. We generated a self-amplifying mRNA vaccine encoding the influenza A virus nucleoprotein that is encapsulated in modified dendron-based nanoparticles. Here, we report how routes of immunization in mice, including contralateral versus ipsilateral intramuscular boosts, or intravenous and intranasal routes, influenced influenza-specific cell-mediated and humoral immunity. Parabiotic surgeries revealed that intramuscular immunization was sufficient to establish CD8 TRM in the lung and draining lymph nodes. Contralateral, compared with ipsilateral, intramuscular boosting broadened the distribution of lymph node TRM and T follicular helper cells but slightly diminished resulting levels of serum antibody. Intranasal mRNA delivery established modest circulating CD8 and CD4 T cell memory but augmented distribution to the respiratory mucosa. Combining intramuscular immunizations with an intranasal mRNA boost achieved high levels of both circulating T cell memory and lung TRM. Thus, routes of mRNA vaccination influence humoral and cell-mediated immunity, and intramuscular prime-boosting establishes lung TRM that can be further expanded by an additional intranasal immunization.
Asunto(s)
Linfocitos T CD4-Positivos , Vacunación , Animales , Ratones , ARN Mensajero , Anticuerpos Neutralizantes , Linfocitos T CD8-positivos , Vacunas de ARNmRESUMEN
Gastrointestinal health depends on the adaptive immune system tolerating the foreign proteins in food1,2. This tolerance is paradoxical because the immune system normally attacks foreign substances by generating inflammation. Here we addressed this conundrum by using a sensitive cell enrichment method to show that polyclonal CD4+ T cells responded to food peptides, including a natural one from gliadin, by proliferating weakly in secondary lymphoid organs of the gut-liver axis owing to the action of regulatory T cells. A few food-specific T cells then differentiated into T follicular helper cells that promoted a weak antibody response. Most cells in the expanded population, however, lacked canonical T helper lineage markers and fell into five subsets dominated by naive-like or T follicular helper-like anergic cells with limited capacity to form inflammatory T helper 1 cells. Eventually, many of the T helper lineage-negative cells became regulatory T cells themselves through an interleukin-2-dependent mechanism. Our results indicate that exposure to food antigens causes cognate CD4+ naive T cells to form a complex set of noncanonical hyporesponsive T helper cell subsets that lack the inflammatory functions needed to cause gut pathology and yet have the potential to produce regulatory T cells that may suppress it.
Asunto(s)
Linfocitos T CD4-Positivos , Alimentos , Tolerancia Inmunológica , Alérgenos/inmunología , Formación de Anticuerpos , Linfocitos T CD4-Positivos/citología , Linfocitos T CD4-Positivos/inmunología , Proteínas en la Dieta/inmunología , Tracto Gastrointestinal/citología , Tracto Gastrointestinal/inmunología , Gliadina/inmunología , Tolerancia Inmunológica/inmunología , Inflamación , Interleucina-2/inmunología , Hígado/citología , Hígado/inmunología , Tejido Linfoide/citología , Tejido Linfoide/inmunología , Fragmentos de Péptidos/inmunología , Células T Auxiliares Foliculares/citología , Células T Auxiliares Foliculares/inmunología , Linfocitos T Reguladores/citología , Linfocitos T Reguladores/inmunología , Células TH1/citología , Células TH1/inmunologíaRESUMEN
Immunosuppressed patients with inflammatory bowel disease (IBD) generate lower amounts of SARS-CoV-2 spike antibodies after mRNA vaccination than healthy controls. We assessed SARS-CoV-2 spike S1 receptor binding domain-specific (S1-RBD-specific) B lymphocytes to identify the underlying cellular defects. Patients with IBD produced fewer anti-S1-RBD antibody-secreting B cells than controls after the first mRNA vaccination and lower amounts of total and neutralizing antibodies after the second. S1-RBD-specific memory B cells were generated to the same degree in IBD and control groups and were numerically stable for 5 months. However, the memory B cells in patients with IBD had a lower S1-RBD-binding capacity than those in controls, which is indicative of a defect in antibody affinity maturation. Administration of a third shot to patients with IBD elevated serum antibodies and generated memory B cells with a normal antigen-binding capacity. These results show that patients with IBD have defects in the formation of antibody-secreting B cells and affinity-matured memory B cells that are corrected by a third vaccination.
Asunto(s)
COVID-19 , Enfermedades Inflamatorias del Intestino , Anticuerpos Antivirales , COVID-19/prevención & control , Humanos , Células B de Memoria , ARN Mensajero , SARS-CoV-2 , Glicoproteína de la Espiga del CoronavirusRESUMEN
Atherosclerotic cardiovascular diseases are the major cause of death worldwide. CD4 T cells responding to Apolipoprotein B (ApoB), the core protein of most lipoproteins, have been identified as critical disease modulators. In healthy individuals, ApoB-reactive (ApoB+) CD4 T cells are mostly regulatory T cells (Tregs), which exert anti-inflammatory effects. Yet, they may obtain pro-inflammatory features and thus become proatherogenic. Evidence from animal studies suggests that vaccination against certain major histocompatibility complex (MHC) II-binding ApoB peptides induces an expansion of ApoB+ Tregs and thus confers atheroprotection. To date, in-depth phenotyping of vaccine-expanded ApoB+ T cells has not yet been performed. To this end, we vaccinated C57BL/6J mice with the ApoB-peptide P6 (ApoB978-993 TGAYSNASSTESASY) and performed single-cell RNA sequencing of tetramer-sorted P6+ T cells. P6+ cells were clonally expanded (one major, two minor clones) and formed a transcriptional cluster distinct from clusters mainly containing non-expanded P6+ and P6- cells. Transcriptomic profiling revealed that most expanded P6+ cells had a strong Treg signature and highly expressed genes mediating suppressive functions. Yet, some expanded P6+ cells only had a residual Treg signature and expressed genes related to T helper 1 (TH1) cells, which are proatherogenic. Modeling the T cell receptor (TCR) and P6:MHC-II interaction showed that only three amino acid residues in the α and ß chain contact the P6 peptide in the MHC-II groove and thus determine the specificity of this TCR to P6. Our data begin to reveal the vaccination-induced response to an ApoB epitope.
RESUMEN
Although both infections and vaccines induce memory B cell (MBC) populations that participate in secondary immune responses, the MBCs generated in each case can differ. Here, we compare SARS-CoV-2 spike receptor binding domain (S1-RBD)-specific primary MBCs that form in response to infection or a single mRNA vaccination. Both primary MBC populations have similar frequencies in the blood and respond to a second S1-RBD exposure by rapidly producing plasmablasts with an abundant immunoglobulin (Ig)A+ subset and secondary MBCs that are mostly IgG+ and cross-react with the B.1.351 variant. However, infection-induced primary MBCs have better antigen-binding capacity and generate more plasmablasts and secondary MBCs of the classical and atypical subsets than do vaccine-induced primary MBCs. Our results suggest that infection-induced primary MBCs have undergone more affinity maturation than vaccine-induced primary MBCs and produce more robust secondary responses.
Asunto(s)
Vacunas contra la COVID-19/inmunología , Células Plasmáticas/inmunología , SARS-CoV-2/inmunología , Adulto , Animales , Anticuerpos Antivirales/inmunología , Subgrupos de Linfocitos B/inmunología , Linfocitos B/inmunología , COVID-19/inmunología , COVID-19/metabolismo , Reacciones Cruzadas/inmunología , Femenino , Células HEK293 , Humanos , Inmunización/métodos , Memoria Inmunológica , Masculino , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , ARN Mensajero/inmunología , SARS-CoV-2/patogenicidad , Glicoproteína de la Espiga del Coronavirus/inmunología , Glicoproteína de la Espiga del Coronavirus/metabolismo , Vacunación/métodos , Vacunas/inmunologíaRESUMEN
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the COVID-19 pandemic. Neutralizing Abs target the receptor binding domain of the spike (S) protein, a focus of successful vaccine efforts. Concerns have arisen that S-specific vaccine immunity may fail to neutralize emerging variants. We show that vaccination with a human adenovirus type 5 vector expressing the SARS-CoV-2 nucleocapsid (N) protein can establish protective immunity, defined by reduced weight loss and viral load, in both Syrian hamsters and K18-hACE2 mice. Challenge of vaccinated mice was associated with rapid N-specific T cell recall responses in the respiratory mucosa. This study supports the rationale for including additional viral Ags in SARS-CoV-2 vaccines, even if they are not a target of neutralizing Abs, to broaden epitope coverage and immune effector mechanisms.
Asunto(s)
Anticuerpos Antivirales/inmunología , Linfocitos T CD8-positivos/inmunología , Vacunas contra la COVID-19/inmunología , COVID-19/prevención & control , Proteínas de la Nucleocápside de Coronavirus/inmunología , SARS-CoV-2/inmunología , Animales , Anticuerpos Neutralizantes/inmunología , COVID-19/inmunología , Línea Celular , Chlorocebus aethiops , Cricetinae , Femenino , Memoria Inmunológica/inmunología , Recuento de Linfocitos , Masculino , Ratones , Ratones Endogámicos C57BL , Fosfoproteínas/inmunología , Vacunación , Células VeroRESUMEN
Lung-localized CD4 T cells play a critical role in the control of influenza virus infection and can provide broadly protective immunity. However, current influenza vaccination strategies primarily target influenza hemagglutinin (HA) and are administered peripherally to induce neutralizing antibodies. We have used an intranasal vaccination strategy targeting the highly conserved influenza nucleoprotein (NP) to elicit broadly protective lung-localized CD4 T cell responses. The vaccine platform consists of a self-assembling nanolipoprotein particle (NLP) linked to NP with an adjuvant. We have evaluated the functionality, in vivo localization, and persistence of the T cells elicited. Our study revealed that intranasal vaccination elicits a polyfunctional subset of lung-localized CD4 T cells that persist long term. A subset of these lung CD4 T cells localize to the airway, where they can act as early responders following encounter with cognate antigen. Polyfunctional CD4 T cells isolated from airway and lung tissue produce significantly more effector cytokines IFN-γ and TNF-α, as well as cytotoxic functionality. When adoptively transferred to naive recipients, CD4 T cells from NLP:NP-immunized lung were sufficient to mediate 100% survival from lethal challenge with H1N1 influenza virus. IMPORTANCE Exploiting new, more efficacious strategies to potentiate influenza virus-specific immune responses is important, particularly for at-risk populations. We have demonstrated the promise of direct intranasal protein vaccination to establish long-lived immunity in the lung with CD4 T cells that possess features and positioning in the lung that are associated with both immediate and long-term immunity, as well as demonstrating direct protective potential.
Asunto(s)
Antígenos Virales/inmunología , Linfocitos T CD4-Positivos/inmunología , Vacunas contra la Influenza/inmunología , Pulmón/inmunología , Infecciones por Orthomyxoviridae/prevención & control , Vacunación/métodos , Adyuvantes Inmunológicos/administración & dosificación , Adyuvantes Inmunológicos/química , Administración Intranasal , Traslado Adoptivo , Animales , Antígenos Virales/administración & dosificación , Antígenos Virales/química , Linfocitos T CD4-Positivos/trasplante , Inmunidad Mucosa , Inmunización Secundaria , Memoria Inmunológica , Subtipo H1N1 del Virus de la Influenza A/inmunología , Vacunas contra la Influenza/administración & dosificación , Vacunas contra la Influenza/química , Lipoproteínas/administración & dosificación , Lipoproteínas/química , Lipoproteínas/inmunología , Pulmón/irrigación sanguínea , Ratones , Nanopartículas/administración & dosificación , Nanopartículas/química , Proteínas de la Nucleocápside/química , Proteínas de la Nucleocápside/inmunología , Infecciones por Orthomyxoviridae/inmunología , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/trasplanteRESUMEN
The ability to identify T cells that recognize specific peptide antigens bound to major histocompatibility complex (MHC) molecules has enabled enumeration and molecular characterization of the lymphocytes responsible for cell-mediated immunity. Fluorophore-labeled peptide:MHC class I (p:MHCI) tetramers are well-established reagents for identifying antigen-specific CD8+ T cells by flow cytometry, but efforts to extend the approach to CD4+ T cells have been less successful, perhaps owing to lower binding strength between CD4 and MHC class II (MHCII) molecules. Here we show that p:MHCII tetramers engineered by directed evolution for enhanced CD4 binding outperform conventional tetramers for the detection of cognate T cells. Using the engineered tetramers, we identified about twice as many antigen-specific CD4+ T cells in mice immunized against multiple peptides than when using traditional tetramers. CD4 affinity-enhanced p:MHCII tetramers, therefore, allow direct sampling of antigen-specific CD4+ T cells that cannot be accessed with conventional p:MHCII tetramer technology. These new reagents could provide a deeper understanding of the T cell repertoire.
Asunto(s)
Linfocitos T CD4-Positivos , Colorantes Fluorescentes , Antígenos de Histocompatibilidad Clase II , Animales , Antígenos CD4/química , Antígenos CD4/metabolismo , Linfocitos T CD4-Positivos/citología , Linfocitos T CD4-Positivos/metabolismo , Células Cultivadas , Femenino , Citometría de Flujo , Colorantes Fluorescentes/química , Colorantes Fluorescentes/metabolismo , Antígenos de Histocompatibilidad Clase II/química , Antígenos de Histocompatibilidad Clase II/metabolismo , Ratones , Ratones Endogámicos BALB CRESUMEN
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the COVID-19 pandemic. Neutralizing antibodies target the receptor binding domain of the spike (S) protein, a focus of successful vaccine efforts. Concerns have arisen that S-specific vaccine immunity may fail to neutralize emerging variants. We show that vaccination with HAd5 expressing the nucleocapsid (N) protein can establish protective immunity, defined by reduced weight loss and viral load, in both Syrian hamsters and k18-hACE2 mice. Challenge of vaccinated mice was associated with rapid N-specific T cell recall responses in the respiratory mucosa. This study supports the rationale for including additional viral antigens, even if they are not a target of neutralizing antibodies, to broaden epitope coverage and immune effector mechanisms.
RESUMEN
Naive CD4+ T cells become memory cells after proliferating in response to their cognate major histocompatibility complex class II (MHCII)-bound peptide and passing through an effector cell stage. The process by which CD4+ memory T cells emerge from the effector cell pool, however, is less well understood than in the case of CD8+ T cells. During certain acute infections, naive CD4+ T cells proliferate and differentiate into various forms of type 1 (Th1) and follicular helper (Tfh) effector cells. We review the evidence that about 10% of the cells in each of these subsets survive to become memory cells that resemble their effector cell precursors. The roles that asymmetric cell division, the TCF-1 transcription factor, metabolic activity, reactive oxygen species, and the IL-7 receptor play in the effector to memory cell transition are discussed. We propose a speculative model in which the metabolic activity needed for rapid clonal expansion also generates toxic products that induce apoptosis in most effector cells. Memory cells then arise from the effector cells in each subset that are at the low end of the metabolic activity spectrum.
Asunto(s)
Linfocitos T CD8-positivos , Memoria Inmunológica , Linfocitos T CD4-Positivos , Células T de MemoriaRESUMEN
Interferon-γ (IFN-γ)-producing CD4+ T helper-1 (Th1) cells are critical for protection from microbes that infect the phagosomes of myeloid cells. Current understanding of Th1 cell differentiation is based largely on reductionist cell culture experiments. We assessed Th1 cell generation in vivo by studying antigen-specific CD4+ T cells during infection with the phagosomal pathogen Salmonella enterica (Se), or influenza A virus (IAV), for which CD4+ T cells are less important. Both microbes induced T follicular helper (Tfh) and interleukin-12 (IL-12)-independent Th1 cells. During Se infection, however, the Th1 cells subsequently outgrew the Tfh cells via an IL-12-dependent process and formed subsets with increased IFN-γ production, ZEB2-transcription factor-dependent cytotoxicity, and capacity to control Se infection. Our results indicate that many infections induce a module that generates Tfh and poorly differentiated Th1 cells, which is followed in phagosomal infections by an IL-12-dependent Th1 cell amplification module that is critical for pathogen control.
Asunto(s)
Diferenciación Celular/inmunología , Células TH1/inmunología , Animales , Linfocitos T CD4-Positivos/inmunología , Línea Celular , Drosophila/inmunología , Femenino , Interferón gamma/inmunología , Interleucina-12/inmunología , Activación de Linfocitos/inmunología , Masculino , Ratones Endogámicos C57BL , Linfocitos T Colaboradores-Inductores/inmunologíaRESUMEN
OBJECTIVES: To avoid the significant risks posed by the use of COVID-19 serology tests with supply chain constraints or poor performance characteristics, we developed an in-house SARS-CoV-2 total antibody test. Our test was compared with three commercial methods, and was used to determine COVID-19 seroprevalence among healthcare workers and outpatients in Minnesota. METHODS: Seventy-nine plasma and serum samples from 50 patients 4-69 days after symptom onset who tested positive by a SARS-CoV-2 PCR method using a nasopharyngeal (NP) swab were used to evaluate our test's clinical performance. Seropositive samples were analyzed for IgG titers in a follow-up assay. Thirty plasma and serum from 12 patients who tested negative by a SARS-CoV-2 PCR method using a nasopharyngeal (NP) swab and 210 negative pre-pandemic serum samples were also analyzed. Among samples from patients > 14 days after symptom onset, the assay had 100% clinical sensitivity and 100% clinical specificity, 100% positive predictive value and 100% negative predictive value. Analytical specificity was 99.8%, indicating minimal cross-reactivity. A screening study was conducted to ascertain COVID-19 seroprevalence among healthcare workers and outpatients in Minnesota. RESULTS: Analysis of serum collected between April 13 and May 21, 2020 indicated a COVID-19 seroprevalence of 2.96% among 1,282 healthcare workers and 4.46% among 2,379 outpatients. CONCLUSIONS: Our in-house SARS-CoV-2 total antibody test can be used to conduct reliable epidemiological studies to inform public health decisions during the COVID-19 pandemic.
Asunto(s)
Prueba Serológica para COVID-19/métodos , COVID-19/diagnóstico , COVID-19/epidemiología , Personal de Salud , Pacientes Ambulatorios , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Anticuerpos Antivirales/sangre , COVID-19/inmunología , Niño , Preescolar , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Inmunoglobulina G/sangre , Lactante , Masculino , Persona de Mediana Edad , Minnesota/epidemiología , SARS-CoV-2/aislamiento & purificación , Estudios Seroepidemiológicos , Adulto JovenRESUMEN
The magnitude of SARS-CoV-2-specific T cell responses correlates inversely with human disease severity, suggesting T cell involvement in primary control. Whereas many COVID-19 vaccines focus on establishing humoral immunity to viral spike protein, vaccine-elicited T cell immunity may bolster durable protection or cross-reactivity with viral variants. To better enable mechanistic and vaccination studies in mice, we identified a dominant CD8 T cell SARS-CoV-2 nucleoprotein epitope. Infection of human ACE2 transgenic mice with SARS-CoV-2 elicited robust responses to H2-Db/N219-227, and 40% of HLA-A*02+ COVID-19 PBMC samples isolated from hospitalized patients responded to this peptide in culture. In mice, i.m. prime-boost nucleoprotein vaccination with heterologous vectors favored systemic CD8 T cell responses, whereas intranasal boosting favored respiratory immunity. In contrast, a single i.v. immunization with recombinant adenovirus established robust CD8 T cell memory both systemically and in the respiratory mucosa.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Vacunas contra la COVID-19/inmunología , COVID-19/inmunología , COVID-19/prevención & control , Epítopos de Linfocito T/inmunología , SARS-CoV-2/inmunología , Vacunación/métodos , Enzima Convertidora de Angiotensina 2/genética , Enzima Convertidora de Angiotensina 2/metabolismo , Animales , COVID-19/virología , Células Cultivadas , Proteínas de la Nucleocápside de Coronavirus/inmunología , Modelos Animales de Enfermedad , Femenino , Vectores Genéticos/inmunología , Antígeno HLA-A2/inmunología , Humanos , Ratones , Ratones Endogámicos C57BL , Ratones TransgénicosRESUMEN
BACKGROUND: The transfer of passive immunity with convalescent plasma is a promising strategy for treatment and prevention of COVID-19, but donors with a history of nonsevere disease are serologically heterogenous. The relationship between SARS-Cov-2 antigen-binding activity and neutralization activity in this population of donors has not been defined. STUDY DESIGN AND METHODS: Convalescent plasma units from 47 individuals with a history of nonsevere COVID-19 were assessed for antigen-binding activity of using three clinical diagnostic serology assays (Beckman, DiaSorin, and Roche) with different SARS-CoV-2 targets. These results were compared with functional neutralization activity using a fluorescent reporter strain of SARS-CoV-2 in a microwell assay. RESULTS: Positive correlations of varying strength (Spearman r = 0.37-0.52) between antigen binding and viral neutralization were identified. Donors age 48 to 75 years had the highest neutralization activity. Units in the highest tertile of binding activity for each assay were enriched (75%-82%) for those with the highest levels of neutralization. CONCLUSION: The strength of the relationship between antigen-binding activity and neutralization varies depending on the clinical assay used. Units in the highest tertile of binding activity for each assay are predominantly comprised of those with the greatest neutralization activity.
Asunto(s)
SARS-CoV-2/inmunología , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , COVID-19/inmunología , COVID-19/terapia , Prueba Serológica para COVID-19 , Ensayo de Inmunoadsorción Enzimática , Humanos , Inmunización Pasiva , Inmunoglobulina G/inmunología , SARS-CoV-2/patogenicidad , Pruebas Serológicas , Sueroterapia para COVID-19RESUMEN
Immunodominance to nonneutralizing epitopes is a roadblock in designing vaccines against several diseases of high interest. One hypothetical possibility is that limited CD4 T cell help to B cells in a normal germinal center (GC) response results in selective recruitment of abundant, immunodominant B cells. This is a central issue in HIV envelope glycoprotein (Env) vaccine designs, because precursors to broadly neutralizing epitopes are rare. Here, we sought to elucidate whether modulating the quantity of T cell help can influence recruitment and competition of broadly neutralizing antibody precursor B cells at a physiological precursor frequency in response to Env trimer immunization. To do so, two new Env-specific CD4 transgenic (Tg) T cell receptor (TCR) mouse lines were generated, carrying TCR pairs derived from Env-protein immunization. Our results suggest that CD4 T cell help quantitatively regulates early recruitment of rare B cells to GCs.
Asunto(s)
Linfocitos B/inmunología , Linfocitos T CD4-Positivos/inmunología , Centro Germinal/inmunología , VIH-1/inmunología , Productos del Gen env del Virus de la Inmunodeficiencia Humana/inmunología , Vacunas contra el SIDA/inmunología , Animales , Anticuerpos Neutralizantes/inmunología , Antígenos Virales/inmunología , Línea Celular , Epítopos/inmunología , Femenino , Células HEK293 , Anticuerpos Anti-VIH/inmunología , Infecciones por VIH/inmunología , Infecciones por VIH/virología , Humanos , Inmunización/métodos , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Transgénicos , Vacunación/métodosRESUMEN
Although CD4+ T cell memory is a critical component of adaptive immunity, antigen-specific CD4+ T cell recall responses to secondary infection have been inadequately studied. Here we examine the kinetics of the secondary response in an important immunological model, infection with attenuated Listeria monocytogenes (Lm). We identify CD4+ T cell subsets that preferentially expand during a secondary response and highlight the importance of prime-boost strategies in expanding and maintaining antigen-specific, tissue-resident memory CD4+ T cells. Following intravenous infection with an attenuated strain of Lm, we found that total antigen-specific CD4+ T cells responded more robustly in secondary compared with primary infection, reaching near-peak levels in secondary lymphoid organs (SLOs) and the liver by three days post-infection. During the secondary response, CD4+ T cells also contracted more quickly. Primary Lm infection generated two main classes of effector cells: Th1 cells that assist macrophages and T follicular helper (Tfh) cells that aid B cells in antibody production. We found that during the secondary response, a population of Ly6C+ Tfh cells emerged in SLOs and was the basis for the skewing of this response to a Tfh phenotype. Deletion of T-bet in T cells precluded development of Ly6C+ Tfh cells, but did not alter anti-Lm antibody responses. Moreover, during recall responses, CD49a+ Th1 cells preferentially expanded and accumulated in the liver, achieving a new set point. Parabiosis experiments indicated that, in contrast to Tfh cells and most splenic Th1 cells, the majority of CD49a+ Th1 cells in the liver were tissue resident. Overall, these data demonstrate a robust secondary CD4+ T cell response that differs in kinetics and composition from the primary response and provide insight into targets to enhance both peripheral and tissue-resident CD4+ T cell responses.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Memoria Inmunológica , Listeriosis/inmunología , Subgrupos de Linfocitos T/inmunología , Animales , Epítopos , Inmunofenotipificación , Cinética , Listeria monocytogenes , Hígado/inmunología , Activación de Linfocitos , Tejido Linfoide/inmunología , Ratones , Ratones Endogámicos C57BL , Parabiosis , Organismos Libres de Patógenos Específicos , Proteínas de Dominio T Box/deficiencia , Proteínas de Dominio T Box/fisiología , Células TH1/inmunologíaRESUMEN
We determined the antigen binding activity of convalescent plasma units from 47 individuals with a history of non-severe COVID-19 using three clinical diagnostic serology assays (Beckman, DiaSorin, and Roche) with different SARS-CoV-2 targets. We compared these results with functional neutralization activity using a fluorescent reporter strain of SARS-CoV-2 in a microwell assay. This revealed positive correlations of varying strength (Spearman r = 0.37-0.52) between binding and neutralization. Donors age 48-75 had the highest neutralization activity. Units in the highest tertile of binding activity for each assay were enriched (75-82%) for those with the highest levels of neutralization.
RESUMEN
Deletion or Treg cell differentiation are alternative fates of autoreactive MHCII-restricted thymocytes. How these different modes of tolerance determine the size and composition of polyclonal cohorts of autoreactive T cells with shared specificity is poorly understood. We addressed how tolerance to a naturally expressed autoantigen of the central nervous system shapes the CD4 T cell repertoire. Specific cells in the tolerant peripheral repertoire either were Foxp3+ or displayed anergy hallmarks and, surprisingly, were at least as frequent as in the nontolerant repertoire. Despite this apparent lack of deletional tolerance, repertoire inventories uncovered that some T cell receptors (TCRs) were lost from the CD4 T cell pool, whereas others mediated Treg cell differentiation. The antigen responsiveness of these TCRs supported an affinity model of central tolerance. Importantly, the contribution of different diverter TCRs to the nascent thymic Treg cell population reflected their antigen reactivity rather than their frequency among precursors. This reveals a multilayered TCR hierarchy in CD4 T cell tolerance that separates deleted and diverted TCRs and assures that the Treg cell compartment is filled with cells of maximal permissive antigen reactivity.