CD2 marginally improves the proliferative response of H-2^b 2C CD4⁻CD8⁺ thymocytes and lymph node cells to stimulation by H-2^d antigens. Equivalent number of CD4⁻CD8⁺ thymocytes or lymph node cells from the indicated mice were cultured with the indicated spleen cells with or without added IL-2. The proliferative responses of the responder cells to stimulation by (C57BL/6 × DBA/2)F₁ (bd) and C57BL/6 (bb) spleen cells are shown.