Figure 4.

(A) Viable cell counts after culture of D011 CD4⁺ cells with H2-A^d Dros APC expressing the indicated costimulatory molecules. Purified D011 CD4⁺ cells (2 × 10⁶) were cultured with Dros APC and 1 μM ova peptide in 5-ml cultures. On the indicated day of assay, viable cell counts were determined by phase microscopy. (B) D011 CD4⁺ cells were labeled with CFSE as described before culture as above with Dros APC expressing the indicated accessory molecules. The results shown were analyzed on day 3 of culture.