Figure 2.

Alanine-substituted peptides: Ala-55, Ala-60, Ala-62, and Ala-63 can bind to I-A^g7 specifically. Different concentrations of alanine-substituted Eα 52–68 peptide (Ala-55, Ala-60, Ala-62, and Ala-63) or an unrelated nonbinding control peptide (HEL 48–61) were assayed for its ability to compete with OVA 323–339 peptide and block the T cell response of OVA-1 T cell clone. Competitor peptides plus 1 μM of 323–339 OVA peptide were incubated in the presence of 5 × 10³ OVA T cells and 5 × 10³ C3.G7 irradiated cells for 24 hr. Later, 25 μl of culture supernatant was removed and tested for IL-3 production by using FDCP3 cells as indicator cells.