Heterologous booster vaccination enhances antibody responses to SARS-CoV-2 by improving Tfh function and increasing B-cell clonotype SHM frequency.

Heterologous prime-boost has broken the protective immune response bottleneck of the COVID-19 vaccines. however, the underlying mechanisms have not been fully elucidated. Here, we investigated antibody responses and explored the response of germinal center (GC) to priming with inactivated vaccines and boosting with heterologous adenoviral-vectored vaccines or homologous inactivated vaccines in mice. Antibody responses were dramatically enhanced by both boosting regimens. Heterologous immunization induced more robust GC activation, characterized by increased Tfh cell populations and enhanced helper function. Additionally, increased B-cell activation and antibody production were observed in a heterologous regimen. Libra-seq was used to compare the differences of S1-, S2- and NTD-specific B cells between homologous and heterologous vaccination, respectively. S2-specific CD19+ B cells presented increased somatic hypermutations (SHMs), which were mainly enriched in plasma cells. Moreover, a heterologous booster dose promoted the clonal expansion of B cells specific to S2 and NTD regions. In conclusion, the functional role of Tfh and B cells following SARS-CoV-2 heterologous vaccination may be important for modulating antibody responses. These findings provide new insights for the development of SARS-CoV-2 vaccines that induce more robust antibody response.

Circular RNA CircZNF644 Facilitates Circulating Follicular Helper T Cells Response in Patients with Graves' Disease.

Aberrant accumulation of circulating follicular helper T cells (cTfh) has been found in the peripheral blood mononuclear cells (PBMCs) of Graves' disease (GD) patients. However, the underlying mechanism that contributes to the imbalance of cTfh cells remains unknown. Previously, studies described a GD-related circular RNAs (circRNAs)-circZNF644 that might be associated with cTfh cells. This study aimed to investigate the role of circZNF644 on cTfh cells in GD patients. Here, we found that circZNF644 was highly stable expression in the PBMCs of GD patients, which was positively correlated with the serum levels of TSH receptor autoantibodies (TRAb). Knockdown of circZNF644 caused a reduction of the proportion of cTfh cells in vitro. Mechanistically, circZNF644 served as a ceRNA for miR-29a-3p to promote ICOS expression, resulting in increased cTfh cells. In the PBMCs of GD patients, circZNF644 expression was positively correlated with ICOS expression and the percentage of cTfh cells, but negatively related to miR-29a-3p expression. Additionally, a strong relationship between circZNF644 and IL-21 was revealed in GD patients, and silencing of circZNF644 inhibited IL-21 expression. Our study elucidated that elevated expression of circZNF644 is a key feature in the development of GD and may contribute to the pathogenic role of cTfh cells in GD.

Coordinated expansion of memory T follicular helper and B cells mediates spontaneous clearance of HCV reinfection.

Introduction: Follicular helper T cells are essential for helping in the maturation of B cells and the production of neutralizing antibodies (NAbs) during primary viral infections. However, their role during recall responses is unclear. Here, we used hepatitis C virus (HCV) reinfection in humans as a model to study the recall collaborative interaction between circulating CD4 T follicular helper cells (cTfh) and memory B cells (MBCs) leading to the generation of NAbs. Methods: We evaluated this interaction longitudinally in subjects who have spontaneously resolved primary HCV infection during a subsequent reinfection episode that resulted in either another spontaneous resolution (SR/SR, n = 14) or chronic infection (SR/CI, n = 8). Results: Both groups exhibited virus-specific memory T cells that expanded upon reinfection. However, early expansion of activated cTfh (CD4+CXCR5+PD-1+ICOS+FoxP3-) occurred in SR/SR only. The frequency of activated cTfh negatively correlated with time post-infection. Concomitantly, NAbs and HCV-specific MBCs (CD19+CD27+IgM-E2-Tet+) peaked during the early acute phase in SR/SR but not in SR/CI. Finally, the frequency of the activated cTfh1 (CXCR3+CCR6-) subset correlated with the neutralization breadth and potency of NAbs. Conclusion: These results underscore a key role for early activation of cTfh1 cells in helping antigen-specific B cells to produce NAbs that mediate the clearance of HCV reinfection.

Interleukin-1 regulates follicular T cells during the germinal center reaction.

Introduction: Antibody production and the generation of memory B cells are regulated by T follicular helper (Tfh) and T follicular regulatory (Tfr) cells in germinal centers. However, the precise role of Tfr cells in controlling antibody production is still unclear. We have previously shown that both Tfh and Tfr cells express the IL-1R1 agonist receptor, whereas only Tfr cells express the IL-1R2 decoy and IL-1Ra antagonist receptors. We aimed to investigate the role of IL-1 receptors in the regulation of B cell responses by Tfh and Tfr. Methods: We generated mice with IL-1 receptors inactivated in Tfh or Tfr and measured antibody production and cell activation after immunisation. Results: While IL-1ß levels are increased in the draining lymph node after immunisation, antigen-specific antibody levels and cell phenotypes indicated that IL-1ß can activate both Tfh and Tfr cells through IL-1R1 stimulation. Surprisingly, expression of IL-1R2 and IL-1Ra on Tfr cells does not block IL-1 activation of Tfh cells, but rather prevents IL-1/IL-1R1-mediated early activation of Tfr cells. IL-1Rs also regulate the antibody response to autoantigens and its associated pathophysiology in an experimental lupus model. Discussion: Collectively, our results show that IL-1 inhibitory receptors expressed by Tfr cells prevent their own activation and suppressive function, thus licensing IL-1-mediated activation of Tfh cells after immunisation. Further mechanistic studies should unravel these complex interactions between IL-1ß and follicular helper and regulatory T cells and provide new avenues for therapeutic intervention.

TIGIT+Tfh show poor B-helper function and negatively correlate with SARS-CoV-2 antibody titre.

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.

Modifying T cell phenotypes using TYK2 inhibitor and its implications for the treatment of systemic lupus erythematosus.

OBJECTIVES: The tuning effects of JAK/TYK2 inhibitors on the imbalance between T follicular helper (Tfh) and T regulatory (Treg) cells, related to systemic lupus erythematosus (SLE) pathogenesis, were investigated using human peripheral blood samples. METHODS: Peripheral blood mononuclear cells from untreated patients with SLE and healthy controls were analysed. Tfh1 cells were identified in nephritis tissue, and the effect of Tfh1 cells on B-cell differentiation was examined by coculturing naïve B cells with Tfh1 cells. RESULTS: Tfh1 cell numbers were increased in the peripheral blood of patients, and activated Treg cell counts were decreased relative to Tfh1 cell counts. This imbalance in the Tfh to Treg ratio was remarkably pronounced in cases of lupus nephritis, especially in types III and IV active nephritis. Immunohistochemistry revealed Tfh1 cell infiltration in lupus nephritis tissues. Co-culture of Tfh1 cells (isolated from healthy individuals) with naïve B cells elicited greater induction of T-bet+ B cells than controls. In JAK/TYK2-dependent STAT phosphorylation assays using memory CD4+ T cells, IL-12-induced STAT1/4 phosphorylation and Tfh1 cell differentiation were inhibited by both JAK and TYK2 inhibitors. However, phosphorylation of STAT5 by IL-2 and induction of Treg cell differentiation by IL-2+TGFß were inhibited by JAK inhibitors but not by TYK2 inhibitors, suggesting that TYK2 does not mediate the IL-2 signalling pathway. CONCLUSIONS: Tfh1 cells can induce T-bet+ B cell production and may contribute to SLE pathogenesis-associated processes. TYK2 inhibitor may fine-tune the immune imbalance by suppressing Tfh1 differentiation and maintaining Treg cell differentiation, thereby preserving IL-2 signalling, unlike other JAK inhibitors.

Biologics targeting IL-17 sharply reduce circulating T follicular helper and T peripheral helper cell sub-populations in psoriasis.

Introduction: Circulating T follicular helper (cTfh) cells and circulating T peripheral helper (cTph) cells (which share common characteristics with the cTfh population) are implicated in the pathogenesis of immune-mediated and autoimmune diseases such as psoriasis (Ps). Their close interplay with the interleukin 17 (IL-17) axis and the ex vivo effect of IL-17-targeting biologic agents used to treat Ps on them are elusive. This study aimed to investigate the effect of biologics targeting IL-17 on cTfh and cTph cell subpopulations isolated from the blood of patients with Ps. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from patients with Ps at treatment initiation and three months later. Samples were also collected from controls. Cells were stained using monoclonal antibodies. Flow cytometry assessed the fraction of cTfh (CD3+CD4+CXCR5+) and cTph (CD3+CD4+CXCR5-PD-1hi) cells.. Results: Flow cytometric analysis showed increased fractions of activated cTfh subsets including ICOS+ and ICOS+PD-1+ expressing cells, in patients compared to controls. Biologic blocking of IL-17A diminished the cTfh population. Furthermore, ICOS+ and ICOS+PD-1+ sub-populations were also inhibited. Finally, the cTph cell fraction significantly decreased after three months of successful treatment with biologics. Conclusion: Early anti-IL-17-mediated clinical remission in Ps is associated with decreased cTfh and cTph cell subpopulations.

In Situ Characterization of Human Follicular Helper CD4 T Cells.

The development of an effective humoral response to pathogens and immunogens is a multiphase biological process, which is mediated by the coordinated function of specialized immune cell types in secondary lymphoid organs and particularly in T cell and follicular areas. More specifically, within the follicular/germinal center area, the orchestrated interplay between B cells, follicular helper CD4 T cells (Tfh), and stromal cells triggers a cascade of immune reactions leading to the development of memory B cells and plasma cells able to generate effective, antigen-specific antibodies. The role of Tfh cells in this process is critical. Given the need for vaccines capable to induce antibodies of high affinity, neutralizing activity, and durability, understanding the cellular and molecular mechanisms regulating Tfh cell development is of great importance. Here, we describe novel approaches for the comprehensive understanding of these cells and possible implications for future studies in vaccine development and the understanding of the pathogenesis of relevant diseases.

ETV5 promotes lupus pathogenesis and follicular helper T cell differentiation by inducing osteopontin expression.

Follicular helper T (TFH) cells mediate germinal center reactions to generate high affinity antibodies against specific pathogens, and their excessive production is associated with the pathogenesis of systemic autoimmune diseases such as systemic lupus erythematosus (SLE). ETV5, a member of the ETS transcription factor family, promotes TFH cell differentiation in mice. In this study, we examined the role of ETV5 in the pathogenesis of lupus in mice and humans. T cell-specific deletion of Etv5 alleles ameliorated TFH cell differentiation and autoimmune phenotypes in lupus mouse models. Further, we identified SPP1 as an ETV5 target that promotes TFH cell differentiation in both mice and humans. Notably, extracellular osteopontin (OPN) encoded by SPP1 enhances TFH cell differentiation by activating the CD44-AKT signaling pathway. Furthermore, ETV5 and SPP1 levels were increased in CD4+ T cells from patients with SLE and were positively correlated with disease activity. Taken together, our findings demonstrate that ETV5 is a lupus-promoting transcription factor, and secreted OPN promotes TFH cell differentiation.

Pathogenic roles of follicular helper T cells in IgG4-related disease and implications for potential therapy.

IgG4-related disease (IgG4-RD) is a recently described autoimmune disorder characterized by elevated serum IgG4 levels and tissue infiltration of IgG4+ plasma cells in multiple organ systems. Recent advancements have significantly enhanced our understanding of the pathological mechanism underlying this immune-mediated disease. T cell immunity plays a crucial role in the pathogenesis of IgG4-RD, and follicular helper T cells (Tfh) are particularly important in germinal center (GC) formation, plasmablast differentiation, and IgG4 class-switching. Apart from serum IgG4 concentrations, the expansion of circulating Tfh2 cells and plasmablasts may also serve as novel biomarkers for disease diagnosis and activity monitoring in IgG4-RD. Further exploration into the pathogenic roles of Tfh in IgG4-RD could potentially lead to identifying new therapeutic targets that offer more effective alternatives for treating this condition. In this review, we will focus on the current knowledge regarding the pathogenic roles Tfh cells play in IgG4-RD and outline potential therapeutic targets for future clinical intervention.

High interleukin-6 levels induced by COVID-19 pneumonia correlate with increased circulating follicular helper T cell frequency and strong neutralization antibody response in the acute phase of Omicron breakthrough infection.

Background: Acute immune responses to coronavirus disease 2019 (COVID-19) are influenced by variants, vaccination, and clinical severity. Thus, the outcome of these responses may differ between vaccinated and unvaccinated patients and those with and without COVID-19-related pneumonia. In this study, these differences during infection with the Omicron variant were investigated. Methods: A total of 67 patients (including 47 vaccinated and 20 unvaccinated patients) who were hospitalized within 5 days after COVID-19 symptom onset were enrolled in this prospective observational study. Serum neutralizing activity was evaluated using a pseudotyped virus assay and serum cytokines and chemokines were measured. Circulating follicular helper T cell (cTfh) frequencies were evaluated using flow cytometry. Results: Twenty-five patients developed COVID-19 pneumonia on hospitalization. Although the neutralizing activities against wild-type and Delta variants were higher in the vaccinated group, those against the Omicron variant as well as the frequency of developing pneumonia were comparable between the vaccinated and unvaccinated groups. IL-6 and CXCL10 levels were higher in patients with pneumonia than in those without it, regardless of their vaccination status. Neutralizing activity against the Omicron variant were higher in vaccinated patients with pneumonia than in those without it. Moreover, a distinctive correlation between neutralizing activity against Omicron, IL-6 levels, and cTfh proportions was observed only in vaccinated patients. Conclusions: The present study demonstrates the existence of a characteristic relationship between neutralizing activity against Omicron, IL-6 levels, and cTfh proportions in Omicron breakthrough infection.

Osteomyelitis is associated with increased anti-inflammatory response and immune exhaustion.

Introduction: Osteomyelitis (OMS) is a bone infection causing bone pain and severe complications. A balanced immune response is critical to eradicate infection without harming the host, yet pathogens manipulate immunity to establish a chronic infection. Understanding OMS-driven inflammation is essential for disease management, but comprehensive data on immune profiles and immune cell activation during OMS are lacking. Methods: Using high-dimensional flow cytometry, we investigated the detailed innate and adaptive systemic immune cell populations in OMS and age- and sex-matched controls. Results: Our study revealed that OMS is associated with increased levels of immune regulatory cells, namely T regulatory cells, B regulatory cells, and T follicular regulatory cells. In addition, the expression of immune activation markers HLA-DR and CD86 was decreased in OMS, while the expression of immune exhaustion markers TIM-3, PD-1, PD-L1, and VISTA was increased. Members of the T follicular helper (Tfh) cell family as well as classical and typical memory B cells were significantly increased in OMS individuals. We also found a strong correlation between memory B cells and Tfh cells. Discussion: We conclude that OMS skews the host immune system towards the immunomodulatory arm and that the Tfh memory B cell axis is evident in OMS. Therefore, immune-directed therapies may be a promising alternative for eradication and recurrence of infection in OMS, particularly in individuals and areas where antibiotic resistance is a major concern.

Resolvin D1 inhibits T follicular helper cell expansion in systemic lupus erythematosus.

OBJECTIVE: Resolvin D1 (RvD1) is one of the specialized pro-resolving lipid mediators, which control inflammation resolution and regulate immune responses. Previous research showed that RvD1 could block the progression of systemic lupus erythematosus (SLE). However, the detailed mechanism remains to be fully understood. METHOD: Plasma RvD1 levels, and proportions of T follicular helper cells (Tfh cells) were measured in SLE patients and healthy controls. Plasma RvD1 levels and proportions of Tfh cells were quantitated in an MRL/lpr mouse model of lupus treated with RvD1. Naïve CD4+ T cells were purified from MRL/lpr mice to study the effect of RvD1 on Tfh cell differentiation in vitro. RESULTS: In patients, there were significant negative correlations between plasma RvD1 levels and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score, as well as between plasma RvD1 and anti-double-stranded DNA antibody levels, and numbers of peripheral Tfh cells and plasma cells. In MRL/lpr mice, the expected amelioration of disease phenotype and inflammatory response with RvD1 treatment correlated with decreased percentages of Tfh cells and plasma cells. In addition, the differentiation and proliferation of Tfh cells were markedly suppressed by RvD1 in vitro. CONCLUSION: RvD1 may control SLE progression through the suppression of Tfh cell differentiation and subsequent inhibition of B-cell responses.

Human Immunodeficiency Virus-Human Pegivirus Coinfected Individuals Display Functional Mucosal-Associated Invariant T Cells and Follicular T Cells Irrespective of PD-1 Expression.

Human pegivirus (HPgV) appears to alter the prognosis of HIV disease by modulating T cell homeostasis, chemokine/cytokine production, and T cell activation. In this study, we evaluated if HPgV had any 'favorable' impact on the quantity and quality of T cells in HIV-infected individuals. T cell subsets such as CD4lo, CD4hi, and CD8+ T cells, CD4+ MAIT cells, CD8+ MAIT cells, follicular helper T (TFH) cells, and follicular cytotoxic T (TFC) cells were characterized based on the expression of markers associated with immune activation (CD69, ICOS), proliferation (ki67), cytokine production (TNF-α, IFN-γ), and exhaustion (PD-1). HIV+HPgV+ individuals had lower transaminase SGOT (liver) and GGT (biliary) in the plasma than those who were HPgV-. HIV/HPgV coinfection was significantly associated with increased absolute CD4+ T cell counts. HIV+HPgV+ and HIV+HPgV- individuals had highly activated T cell subsets with high expression of CD69 and ICOS on bulk CD4+ and CD8+ T cells, CD4+ MAIT cells, CD8+ MAIT cells, and CXCR5+CD4+ T cells and CXCR5+CD8+ T cells compared with healthy controls. Irrespective of immune activation markers, these cells also displayed higher levels of PD-1 on CD4+ T and CD8+ T cells . Exploring effector functionality based on mitogen stimulation demonstrated increased cytokine production by CD4+ MAIT and CD8+ MAIT cells. Decrease in absolute CD4+ T cell counts correlated positively with intracellular IFN-γ levels by CD4lo T cells, whereas increase of the same correlated negatively with TNF-α in the CD4lo T cells of HIV+HPgV+ individuals. HIV/HPgV coinfected individuals display functional CD4+ and CD8+ MAIT, TFH, and TFC cells irrespective of PD-1 expression.

Effects of anti-CD20 therapy on circulating and intrathecal follicular helper T cell subsets in multiple sclerosis.

Follicular helper T (Tfh) cells and their interplay with B cells likely contribute to the pathogenesis of relapsing-remitting multiple sclerosis (RRMS). Tfh cells are enriched in cerebrospinal fluid (CSF) in RRMS, but effects of anti-CD20 therapy are unknown. We investigated Tfh cells in controls, untreated and anti-CD20-treated patients with RRMS using flow cytometry. CSF Tfh cells were increased in untreated patients. Compared to paired blood samples, CD25- Tfh cells were enriched in CSF in RRMS, but not in controls. Contrast-enhancing brain MRI lesions and IgG index correlated with CSF CD25- Tfh cell frequency in untreated patients with RRMS. Anti-CD20 therapy reduced the numbers of circulating PD1+ Tfh cells and CD25- Tfh cells, and the frequency of CSF CD25- Tfh cells. The study suggests that CD25- Tfh cells are recruited to the CSF in RRMS, associated with focal inflammation, and are reduced by anti-CD20 therapy.

[Process in the role of vasoactive intestinal peptide in the treatment of ulcerative colitis by regulating the balance of T follicular helper cells/T follicular regulatory cells].

Ulcerative colitis (UC) is an autoimmune disease based on the persistent damage of colonic mucosal barrier. It has been found that the abnormal expression of follicular helper T (Tfh) cells and follicular regulatory T (Tfr) cells is closely related to the occurrence and development of UC. Tfh cells can secrete pro-inflammatory factors and assist B cells to produce antibodies, which can promote the development of UC, while Tfr cells can inhibit the activity of Tfh cells and secrete anti-inflammatory factors. How to regulate the balance between them has become one of the potential therapeutic targets of UC. Vasoactive intestinal peptide (VIP) has preventive and therapeutic effect on UC, and its mechanism is closely related to the regulation of Tfh/Tfr cell balance, which can provide help for the treatment of UC.

Immunophenotypic classification regarding prognosis in peripheral T cell lymphoma, NOS, and nodal T follicular helper T cell lymphoma, angioimmunoblastic-type.

This study aimed to determine the clinicopathological predictive factors of peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS), and nodal T-follicular helper cell lymphoma, angioimmunoblastic-type (nTFH, AI-type). In this single-centered, retrospective study, medical records of 59 patients who were diagnosed with PTCL, NOS, or nTFH, AI-type from March 2007 to September 2022 were reviewed. The clinicopathological variables, including immunohistochemistry(IHC) subgroups, distinguishing TBX21 from the GATA3 subgroups were analyzed. Overall, 28 patients (75.7%) in the TBX21 group were PTCL, NOS. There were 9 (24.3%) patients in the GATA3 group. In univariable analyses, lymphoma subtype, age, and performance status were associated with progression-free survival (PFS), and overall survival (OS). In multivariable analyses, lymphoma subtype, and performance status were related to PFS and OS (P = 0.012, P < 0.001, P = 0.006, and P < 0.001, respectively). The GATA3 subgroup tended to have a worse prognosis in univariable analyses; however, it became more insignificant in multivariable when lymphoma subtype and performance status were adjusted (P = 0.065, P = 0.180, P = 0.972, and P = 0.265, respectively). The double-positive group showed variable prognoses of better PFS and worse OS. PD-1 and PD-L1 were associated with the EBV in situ hybridization (P = 0.027, and P = 0.005), and PD-1 was associated with CD30 expression (P = 0.043). This study demonstrated the potential of IHC classification to predict prognosis for PTCL, NOS, as well as nTFH AI-type, although further validation is necessary. Treatments targeting CD30, PD-1, and PD-L1 appear promising for lymphoma treatment.

Tfh cell-derived small extracellular vesicles exacerbate the severity of collagen-induced arthritis by enhancing B-cell responses.

Soluble components secreted by Tfh cells are critical for the germinal center responses. In this study, we investigated whether Tfh cells could regulate the B-cell response by releasing small extracellular vesicles (sEVs). Our results showed that Tfh cells promote B-cell differentiation and antibody production through sEVs and that CD40L plays a crucial role in Tfh-sEVs function. In addition, increased Tfh-sEVs were found in mice with collagen-induced arthritis (CIA). Adoptive transfer of Tfh cells significantly exacerbated the severity of CIA; however, the effect of Tfh cells on exacerbating the CIA process was significantly diminished after inhibiting sEVs secretion. Moreover, the levels of plasma Tfh-like-sEVs and CD40L expression on Tfh-like-sEVs in RA patients were significantly higher than those in healthy subjects. In summary, Tfh cell-derived sEVs can enhance the B-cell response, and exacerbate the procession of autoimmune arthritis.

Accessing Early Differentiation of Virus-Specific Follicular Helper CD4+ T Cell in Acute LCMV-Infected Mice.

Follicular Helper T (TFH) cells are perceived as an independent CD4+ T cell lineage that assists cognate B cells in producing high-affinity antibodies, thus establishing long-term humoral immunity. During acute viral infection, the fate commitment of virus-specific TFH cells is determined in the early infection phase, and investigations of the early-differentiated TFH cells are crucial in understanding T cell-dependent humoral immunity and optimizing vaccine design. In the study, using a mouse model of acute lymphocytic choriomeningitis virus (LCMV) infection and the TCR-transgenic SMARTA (SM) mouse with CD4+ T cells specifically recognizing LCMV glycoprotein epitope I-AbGP66-77, we described procedures to access the early fate commitment of virus-specific TFH cells based on flow cytometry stainings. Furthermore, by exploiting retroviral transduction of SM CD4+ T cells, methods to manipulate gene expression in early-differentiated virus-specific TFH cells are also provided. Hence, these methods will help in studies exploring the mechanism(s) underlying the early commitment of virus-specific TFH cells.