Differential Antigen Sensitivity and Costimulatory Requirements in Human Th1 and Th2 Antigen-Specific CD4+ Cells with Similar TCR Avidity

Abstract

The differentiation of naive CD4+ Th cells into Th1 and Th2 phenotypes is influenced by cytokines, concentration of Ag, accessory molecules, and the affinity of the MHC-TCR interaction. To study these factors in human memory T cells, T cell lines with Th1 or Th2 phenotypes specific for the peptide hemagglutinin (HA)307–319 in the context of DRB1*0401 were established from the peripheral blood of an individual previously vaccinated for influenza virus. Flow cytometric analysis with fluorescent-labeled MHC class II tetramers was used to analyze TCR avidity: the Th2 line bound the HLA-DR*0401-HA307–319 tetramers with higher mean avidity, although the range of binding avidity largely overlapped with the Th1 line. High-affinity Th1 and Th2 lines were established for further study by FACS sorting. When activated with plate-bound HLA-DR*0401-HA307–319 monomers, the Th1 line proliferated and produced IFN-γ without additional costimulation whereas the Th2 line required the addition of soluble anti-CD28 Ab to induce proliferation and IL-5 production, but this requirement could be overcome with high concentrations of plate-bound monomer alone. IL-2 production was dependent on costimulation in both cell lines. These findings demonstrate that upon antigenic rechallenge, Th1 and Th2 cells differ in their response to Ag-specific stimulation. Th2 cells were sensitive to the strength of signal to a greater degree than Th1 cells and required costimulation through CD28 for maximal proliferation. These distinctions between Th1 and Th2 activation are not consistent with a simple avidity model of Ag recognition and indicate both qualitative and quantitative differences in determining cell lineage commitment.

Antigen-Specific CD4+T Cells Recognize Epitopes of Protective Antigen following Vaccination with an Anthrax Vaccine

“…In order to efficiently monitor this latter pathway, various lymphocyte activation assays have been used, often involving the activation or proliferation of CD4 ϩ T cells in vitro as an indirect measure of antigen-specific responses. With the development of pMHC class II tetramers, it is now possible to directly assay the CD4 ϩ T-cell population for antigen-specific phenotypes (2,3,7,(12)(13)(14)22).…”

Analysis of Autoreactive CD4 T Cells in Experimental Autoimmune Encephalomyelitis after Primary and Secondary Challenge Using MHC Class II Tetramers

“…MHC class II multimers have previously been used to detect CD4 T cells specific for viral Ags (27,28) and self Ags (29), including Ags expressed in the CNS (30). The specific binding of the tetramers was first assessed by flow cytometry of polyclonal, in vitro restimulated lymph node cells isolated 8 days after immunization with either of the respective Ags MBP84 -96 or PLP139 -151, (31).…”

The specific T-cell response to antigenic peptides is influenced by bystander peptides

“…However, this is unlikely for two reasons. First, such interactions were reported to be much more important for the induction of the antigen response in naive T cells than in effector T cells [16], although distinct functions of the latter seem to depend on accessory molecules to a different extent [17]. Secondly, an effect of possible differences in the expression of accessory molecules between the antigen-presenting fibroblast lines on T cell response seems unlikely in our experimental system because two independently produced A b wt+A b Ep transfectant cell lines, FT2A b wt+A b Ep and FT7.1A b wt+A b Ep, always stimulated our T cell hybridomas more strongly than the A b Ep transfectants presenting Ep only (Figs 2-6).…”