CD4- and CD8-mediated DTH response in CD44^−/− mice. Four CD44^+/− (closed triangles) and four CD44^−/− (open triangles) mice were immunized (A) on shaved abdomen and rechallenged on one ear with DNFB. Ear thickness is shown as a percentage of swelling compared with the untreated ear. (B) CD44^+/− and CD44^−/− mice were infected with 100 pfu LCMV at day 0, and footpad swelling was measured every day or every other day. Swelling is given as percent increase compared with footpad size before infection.