Increased HSP70-mediated phagocytosis enhances antigen presentation. (A) Yeast (S cerevisiae) was coated with ovalbumin (the whole protein) by coincubation at 37°C for 20 minutes. The complexes (Ova-coated yeast) were administered to macrophages treated with HSP70 (100 μg/mL) or control proteins in the presence or absence of cytochalasin-D. After 2 hours, the macrophages were washed, irradiated (to prevent macrophage-proliferation), and cocultured with CSFE-labeled CD4⁺ T cells purified from spleens of DO11.10 mice (I-A^d-restricted DO11.10 TCR-αβ-transgenic). (The DO11.10 strain is transgenic against a specific MHC-II epitope of ovalbumin protein.) Resultant CD4⁺ proliferation was measured using FACS as an indicator of the amount of the ovalbumin peptide presented in context of MCH-II antigen presentation. (B) Concurrent production of interferon γ (IFNγ) by the CD4⁺ T cells was quantified using ELISA as a measure of their effector function. The data shown represents 1 of 3 independent experiments.