The phenotype of type 1 and type 2 CD8+ T cells activated in vitro is affected by culture conditions and correlates with effector activity.

We used various culture conditions to generate type 1 (Tc1) or type 2 (Tc2) cytotoxic T cells in vitro. T-cell receptor (TCR) transgenic T cells were cultured with antigen and spleen cells, or antigen and dendritic cells (DC), or anti-CD3 and anti-CD28. Tc1 cultures contained interleukin (IL)-2 and IL-6, and Tc2 cultures contained IL-2, IL-6 and IL-4. Tc2 cells generated in each culture condition acquired a CD62L(low) CD44(high) phenotype, had high cytotoxic activity, and secreted IL-4, IL-5 and moderate amounts of interferon-gamma (IFN-gamma). In contrast, the phenotype and function of Tc1 cells varied depending on culture conditions. Tc1 cells from anti-CD3 and anti-CD28 cultures had high cytotoxic activity and were CD62L(low) CD44(high), while Tc1 cells from antigen and spleen cell cultures had low cytotoxic activity and were CD62L(high) CD44(low). Tc1 cells from antigen and DC cultures had an intermediate phenotype. All Tc1 cells secreted high amounts of IFN-gamma, but only Tc1 from anti-CD3 and anti-CD28 cultures had antitumour activity in vivo. Differences were not caused by suboptimal culture conditions, as Tc1 cells divided at a similar rate whether cultured with antigen and spleen cells or with anti-CD3 and anti-CD28. We conclude that IL-4 not only induces 'type 2' cytokine secretion in CD8(+) T cells, but also affects their expression of surface markers and cytotoxic activity.