Fig. 6
Paracrine release of IL-2 from Tmem may potentiate melanoma inhibition by Teff. The local interaction of Teff and Tmem was examined by performing in vitro melanoma inhibition assays. (a) Teff and Tmem and Teff + Tmem were co-cultured with B16GP33 for 8 h. Although melanoma inhibition was comparable between Teff and Tmem, significantly stronger inhibition of melanoma was observed with the combination of Teff + Tmem. (b) Conditioned media (CM) was collected from Tmem stimulated with GP33 for 5 h. The addition of CM enhanced the efficacy of Teff to a similar degree as the addition of Tmem. The effect of CM was negated by the addition of anti-IL-2 blocking antibody; the addition of anti-IL-2 blocking antibody alone did not affect the ability of Teff to inhibit melanoma. The addition of anti-IL-2 blocking antibody blunted the ability of Teff + Tmem to inhibit melanoma, but it could not be determined if this effect was exerted on Teff or Tmem (data not shown). This experiment was repeated twice with similar results, 3 samples per group. (p-values as shown on horizontal bars)