We report the detection of an interleukin-4 (IL-4) variant whose expression is tightly associated with deprivation apoptosis. It is detected with the 8D4 anti-IL-4 monoclonal antibody (mAb) not only in T helper-2 (Th2) but also in Th1 clones, and primary T cells, and it is a nonsecreted molecule. It is not expressed during primary necrosis. Our data suggest that de novo IL-4 transcription of an alternative IL-4 mRNA (IL-4 delta(13)) is induced during deprivation apoptosis. In HIV-infected patients, increased expression of IL-4 in T cells is highly correlated to increased apoptosis, restricted to 8D4 reactivity (r(2) = 0.84 between % 8D4-8(+) and % 7- amino-actinomycin D-positive [7-AAD(+)] peripheral T cells, P <.0001), and associated with disease progression. The particular reactivity of apoptotic T cells to 8D4 mAb may explain some discordances among studies analyzing the Th1/Th2 balance in HIV infection and questions the function of this intracellular type 2 signal.