Figure 4.

APC function of Percoll-isolated B cell fractions. Spleen cells from unprimed B10.S mice were depleted of T cells and fractionated on Percoll density gradients as indicated. Varying numbers (0.6–300 × 10³) of nonirradiated or irradiated (2500R) whole spleen cells or Percoll gradient fractionated cells were used as APC and cultured with the I-A^s-restricted, HBcAg-specific T cell hybridoma 3E3–5G4 (1.2 × 10⁴) and HBcAg (0.2 μg/ml). This HBcAg concentration was chosen to minimize non-B cell APC function. The minimum number of APC per well required to elicit three times the background (i.e., without HBcAg) level of IL-2 production by the T cell hybridoma is shown.