Frequencies of CD4+ and CD8+ T cells producing IL-4, IL-13 after in vitro stimulation were significantly higher in asthma patients than in the control group (IL-4: P < .00001, P < .00003 for CD4+ and CD8+ T cells, resp., IL-13: P < .00001 for CD4+ and CD8+ T cells). This evidence concerns the gene IL4 and asthma.