<p>A LAT assay was performed as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0048635#s2" target="_blank">materials and methods</a> section. Seven days after AC injection, mice were s.c. immunized with CII/CFA. On day 14, putative regulatory spleen cells were isolated and mixed with immune spleen cells (isolated from s.c. immunized mice) and 500 µg CII before injection into the left ear pinna of naïve mice. Positive control mice received immune and naïve spleen cells along with CII. Two negative controls were included; one received only naïve spleen cells along with CII and the other received only CII. The regulatory activity of spleen cells was confirmed by inhibition of ear swelling responses induced by immune spleen cells after 24 hr (panel ‘a’) and 48 hr (panel ‘b’).</p