• IMMUNE NETWORK
• /
• v.13 no.6
• /
• pp.264-274
• /
• 2013

The unrestricted population of $CD4^+Foxp3^+$ regulatory T (Treg) cells, which have been known to control the expression of autoimmune diseases and protective immunity to inflammatory reactions, has led to greater appreciation of functional plasticity. Detecting and/or isolating Ag-specific $CD4^+Foxp3^+$ Tregs at the single cell level are required to study their function and plasticity. In this study, we established and compared both MHC class II tetramer and intracellular CD154 staining, in order to detect $CD4^+Foxp3^+$ Treg specific for foreign Ag in acute and chronic infections with lymphocytic choriomeningitis virus (LCMV). Our results revealed that MHC class II tetramer staining showed a lower detection rate of LCMV $GP_{66-77}$-specific $CD4^+$ T cells because most of MHC class II tetramers were unbound and unstable when combined staining was performed with intracellular cytokines. In contrast, intracellular CD154 staining was revealed to be easier and simple for detecting LCMV $GP_{66-77}$-specific $CD4^+$ T cells, compared to MHC class II tetramer staining. Subsequently, we employed intracellular CD154 staining to detect LCMV $GP_{66-77}$-specific $CD4^+Foxp3^+$ Tregs using $Foxp3^{GFP}$ knock-in mouse, and found that LCMV $GP_{66-77}$-specific $CD4^+Foxp3^+$ Tregs and polyclonal $CD4^+Foxp3^+$ Tregs showed differential expansion in mice infected with LCMV Arms or Cl13 at acute (8 and 13 days pi) and chronic phases (35 days pi). Therefore, our results provide insight into the valuable use of intracellular CD154 staining to detect and characterize foreign Ag-specific $CD4^+Foxp3^+$ Treg in various models.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.12
• /
• pp.1955-1964
• /
• 2007

A recent report showed that analysis of CD154 expression in the presence of the secretion inhibitor Brefeldin A (Bref A) could be used to assess the entire repertoire of antigen-specific $CD4^+\;T$ helper cells. However, the capacity of intracellular CD154 expression to identify antigen-specific $CD8^+\;T$ cells has yet to be investigated. In this study, we compared the ability of intracellular CD154 expression to assess antigen-specific $CD8^+\;T$ cells with that of accepted standard assays, namely intracellular cytokine IFN-${\gamma}$ staining (ICS) and MHC class I tetramer staining. The detection of intracellular CD154 molecules in the presence of Bref A reflected the kinetic trend of antigen-specific $CD8^+\;T$ cell number, but unfortunately showed less sensitivity than ICS and tetramer staining. However, ICS levels peaked and saturated 8 h after antigenic stimulation in the presence of Bref A and then declined, whereas intracellular CD154 expression peaked by 8 h and maintained the saturated level up to 24 h post-stimulation. Moreover, intracellular CD154 expression in antigen-specific $CD8^+\;T$ cells developed in the absence of $CD4^+\;T$ cells changed little, whereas the number of IFN-${\gamma}$-producing $CD8^+\;T$ cells decreased abruptly. These results suggest that intracellular CD154 could aid the assessment of antigen-specific $CD8^+\;T$ cells, but does not have as much ability to identify heterogeneous $CD4^+\;T$ helper cells. Therefore, the combined analytical techniques of ICS and tetramer staining together with intracellular CD154 assays may be able to provide useful information on the accurate phenotype and functionality of antigen-specific $CD8^+\;T$ cells.

• IMMUNE NETWORK
• /
• v.11 no.5
• /
• pp.268-280
• /
• 2011

Background: Dengue virus, which belongs to the Flavivirus genus of the Flaviviridae family, causes fatal dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) with infection risk of 2.5 billion people worldwide. However, approved vaccines are still not available. Here, we explored the immune responses induced by alternating prime-boost vaccination using DNA vaccine, adenovirus, and vaccinia virus expressing E protein of dengue virus type 2 (DenV2). Methods: Following immunization with DNA vaccine (pDE), adenovirus (rAd-E), and/or vaccinia virus (VV-E) expressing E protein, E protein-specific IgG and its isotypes were determined by conventional ELISA. Intracellular CD154 and cytokine staining was used for enumerating CD4+ T cells specific for E protein. E protein-specific CD8+ T cell responses were evaluated by in vivo CTL killing activity and intracellular IFN-${\gamma}$ staining. Results: Among three constructs, VV-E induced the most potent IgG responses, Th1-type cytokine production by stimulated CD4+ T cells, and the CD8+ T cell response. Furthermore, when the three constructs were used for alternating prime-boost vaccination, the results revealed a different pattern of CD4+ and CD8+ T cell responses. i) Priming with VV-E induced higher E-specific IgG level but it was decreased rapidly. ii) Strong CD8+ T cell responses specific for E protein were induced when VV-E was used for the priming step, and such CD8+ T cell responses were significantly boosted with pDE. iii) Priming with rAd-E induced stronger CD4+ T cell responses which subsequently boosted with pDE to a greater extent than VV-E and rAd-E. Conclusion: These results indicate that priming with live viral vector vaccines could induce different patterns of E protein-specific CD4+ and CD8+ T cell responses which were significantly enhanced by booster vaccination with the DNA vaccine. Therefore, our observation will provide valuable information for the establishment of optimal prime-boost vaccination against DenV.