CD154-based detection of food-specific T cells. A, Quantification of CD154+CD4+ T cells after 0, 6, or 18 hours of stimulation with milk, soy, or rice. B, Frequency of CD154+CD4+ T cells in the absence (−) or presence (+) of stimulation with milk, rice, or soy extract (extract matched to challenge food) in unchallenged healthy controls, or in those who reacted (FPIES) or not (outgrown) to a food challenge. C, Frequency of TNF-α+CD154+CD4+ T cells as in Fig 1, B. *P < .05 compared with media control. #P < .05 compared with FPIES.