Project description:A range of current candidate AIDS vaccine regimens are focused on generating protective HIV neutralizing antibody responses. Many of these efforts rely on the rhesus macaque animal model. Understanding how protective antibody responses develop and how to increase their efficacy are both major knowledge gaps. Germinal centers (GC) are the engines of antibody affinity maturation. GC T follicular helper (GC Tfh) CD4 T cells are required for GCs. Studying vaccine-specific GC Tfh cells after protein immunizations has been challenging, as antigen-specific GC Tfh cells are difficult to identify by conventional intracellular cytokine staining (ICS). Cytokine production by GC Tfh cells may be intrinsically limited in comparison to other T helper effector cells, as the biological role of a GC Tfh cell is to provide help to individual B cells within the GC, rather than secreting large amounts of cytokines bathing a tissue. To test this idea, we developed a cytokine-independent method to identify antigen-specific GC Tfh cells. RNAseq was performed using TCR stimulated GC Tfh cells to identify candidate markers based on differentially expressed genes and other criteria. Validation experiments determined CD25 (IL2Ra) and OX40 to be highly upregulated activation induced markers on the surface of GC Tfh cells after stimulation. In comparison to ICS, the activation induced marker (AIM) assay identified > 10-fold more antigen-specific GC Tfh cells in HIV Env protein immunized macaques (BG505 SOSIP). Additionally, the AIM assay detected antigen-specific CXCR5+ and CXCR5- CD4 T cells in peripheral blood. Thus, AIM demonstrates that antigen-specific GC Tfh cells are intrinsically stingy producers of cytokines, which is likely an essential part of their biological function. Total RNA obtained from GC Tfh cells from 3 rhesus macaque lymph node cell samples stimulated with Staphylococcal Enterotoxin B compared with 2 unstimulated cell samples.
Project description:A range of current candidate AIDS vaccine regimens are focused on generating protective HIV neutralizing antibody responses. Many of these efforts rely on the rhesus macaque animal model. Understanding how protective antibody responses develop and how to increase their efficacy are both major knowledge gaps. Germinal centers (GC) are the engines of antibody affinity maturation. GC T follicular helper (GC Tfh) CD4 T cells are required for GCs. Studying vaccine-specific GC Tfh cells after protein immunizations has been challenging, as antigen-specific GC Tfh cells are difficult to identify by conventional intracellular cytokine staining (ICS). Cytokine production by GC Tfh cells may be intrinsically limited in comparison to other T helper effector cells, as the biological role of a GC Tfh cell is to provide help to individual B cells within the GC, rather than secreting large amounts of cytokines bathing a tissue. To test this idea, we developed a cytokine-independent method to identify antigen-specific GC Tfh cells. RNAseq was performed using TCR stimulated GC Tfh cells to identify candidate markers based on differentially expressed genes and other criteria. Validation experiments determined CD25 (IL2Ra) and OX40 to be highly upregulated activation induced markers on the surface of GC Tfh cells after stimulation. In comparison to ICS, the activation induced marker (AIM) assay identified > 10-fold more antigen-specific GC Tfh cells in HIV Env protein immunized macaques (BG505 SOSIP). Additionally, the AIM assay detected antigen-specific CXCR5+ and CXCR5- CD4 T cells in peripheral blood. Thus, AIM demonstrates that antigen-specific GC Tfh cells are intrinsically stingy producers of cytokines, which is likely an essential part of their biological function.
Project description:Identification and isolation of antigen-specific T cells is important for many immunological research areas, including cancer, infectious diseases, and vaccines. We optimized an activation-induced markers (AIM) assay that facilitated detection and scRNA analysis of HCV-specific T cells.
Project description:The identification and study of antigen-specific CD4 T cells, both in peripheral blood and in tissues, is key for a broad range of immunological research, including vaccine responses and infectious diseases. Detection of these cells is hampered by both their rarity and their heterogeneity, in particular with regards to cytokine secretion profiles. These factors prevent the identification of the total pool of antigen-specific CD4 T cells by classical methods. We have developed assays for the highly sensitive detection of such cells by measuring the upregulation of surface activation induced markers (AIM). Here, we compare two such assays based on concurrent expression of CD69 plus CD40L (CD154) or expression of OX40 plus CD25, and we develop additional AIM assays based on OX40 plus PD-L1 or 4-1BB. We compare the relative sensitivity of these assays for detection of vaccine and natural infection-induced CD4 T cell responses and show that these assays identify distinct, but overlapping populations of antigen-specific CD4 T cells, a subpopulation of which can also be detected on the basis of cytokine synthesis. Bystander activation had minimal effect on AIM markers. However, some T regulatory cells upregulate CD25 upon antigen stimulation. We therefore validated AIM assays designed to exclude most T regulatory cells, for both human and non-human primate (NHP, Macaca mulatta) studies. Overall, through head-to-head comparisons and methodological improvements, we show that AIM assays represent a sensitive and valuable method for the detection of antigen-specific CD4 T cells.
Project description:To elucidate differential preventive roles of the blood apoptosis inhibitor of macrophage (AIM) protein in fat deposition and hepatocarcinoma development, we have performed microarray analysis to assess putative difference in expression of genes related to carcinnogenesis in the liver of AIM+/+ and AIM-/- fed a high-fat diet (HFD) for various periods.
Project description:Since T cells are key mediators in the adaptive immune system, evaluating antigen-specific T cell immune responses is pivotal to understanding immune function. Commonly used methods for measuring T cell responses include Activation-Induced Marker (AIM) assays and Intracellular Cytokine Staining (ICS). However, combining these approaches has rarely been reported. This study describes a combined AIM + ICS assay and the effect of collecting the supernatant. Peripheral blood mononuclear cells (PBMCs) from seven healthy donors were stimulated with DMSO (negative control), Epstein-Barr virus (EBV) peptide pools, and PHA (positive control). The AIM markers OX40 + CD137+ were used for CD4+ T cells and CD69 + CD137+ and CD107a + CD137+ for CD8+ T cells. Cytokine-secreting cells were identified as CD40L+ cytokine+ for CD4+ and CD69+ or CD107 + cytokine+ for CD8+ T cells. Half of the supernatant was collected before adding the BFA/Monensin/CD137 antibody solution to assess the impact on T cell responses. The CD107a + CD137+ AIM markers combination had a lower background than CD69 + CD137+, making CD107a+ a more sensitive marker for CD8+ AIM markers. Collecting half of the supernatant did not significantly affect the immune responses. Our AIM + ICS combined protocol enables the simultaneous assessment of activation and cytokine release reducing the sample volume for testing T cell responses. We also show that collecting half of the supernatant does not significantly interfere with immune responses detection.