High levels of human antigen-specific CD4 T cells in peripheral blood revealed by stimulated coexpression of CD25 and CD134 (OX40)

Abstract

Ag-specific human CD4+ memory T lymphocytes have mostly been studied using assays of proliferation in vitro. Intracellular cytokine and ELISPOT assays quantify effector cell populations but barely detect responses to certain recall Ags that elicit strong proliferative responses, e.g., tetanus toxoid, that comprise non-Th1 CD4+ cells. We have found that culturing whole blood with Ag for 40-48 h induces specific CD4+ T cells to simultaneously express CD25 and CD134. This new technique readily detects responses to well-described CD4+ T cell recall Ags, including preparations of mycobacteria, CMV, HSV-1, influenza, tetanus toxoid, Candida albicans, and streptokinase, as well as HIV-1 peptides, w..