Phosphatidylinositol 3-kinase inhibitors prevent mouse cytotoxic T-cell development in vitro

To become competent killer cells, CD8(+) T cells require stimulation throug h signal transduction pathways associated with the T-cell receptor, costimu latory molecules such as CD28, and cytokine receptors such as the interleuk in (IL)-2 receptor, We used wortmannin and LY294002, two inhibitors of phos phatidylinositol 3-kinase (PIS-K), to study the role of PI3-K in mouse cyto toxic T-lymphocyte (CTL) induction in response to mitogenic anti-CD3 antibo dy, Anti-CD3-induced CD8+ T-cell proliferation and CTL development were inh ibited dose dependently by both PIS-K inhibitors, IL-2 synthesis by anti-CD 3-activated CD8+ T cells was also diminished by PTS-K inhibition, PI3-K inh ibition resulted in a modest decrease in anti-CD3-induced CD4(+) T-cell pro liferation but failed to affect IL-2 expression by anti-CD3-activated CD4() T cells, PI3-K inhibition during CTL induction resulted in decreased leve ls of mRNAs coding for granzyme B, perforin, and Fas ligand. In addition, C TL induced in the presence of PI3-K inhibitors failed to conjugate normally with P815 target cells, Exogenous IL-2 did not reverse the effects of PIS- K inhibition on CD8+ T-cell proliferation and CTL induction. These results support the conclusion that PIS-K activation is involved in T-cell receptor , CD28, and IL-2 receptor signaling of CD8+ T cells. PIS-K is, therefore, a n important component of multiple signal transduction pathways involved in CTL generation.