In vivo immnosuppressive effects of CRA. (A-B) BALB/c mice were sensitized on day −4 with OX and challenged on day 0 with the same hapten on the ears. CRA (10 μg/animal) or DMSO alone was intraperitonially injected during the sensitization phase (days −4 and −3) and/or the elicitation phase (days 0 and 1). Data shown are the ear-swelling responses on days 1 and 2 (mean ± SD, n = 10). (C) The mice examined in panel B were resensitized and rechallenged 1 month later with OX or DNFB. Data shown are the ear swelling responses on day 1 (mean ± SD, n = 5). Asterisks indicate statistically significant (**P < .01) differences compared with vehicle-treated mice. (D-E) BALB/c mice received intraperitoneal injection of CRA (10 μg/animal) or DMSO alone, followed immediately by topical application of 1.25% OX or vehicle (acetone/olive oil). The number of MHC class II-positive epidermal cells was counted 24 hours after OX application (mean ± SD, n = 10). (F) BALB/c mice were painted with 10% BAC or 30% EPP on the ears on day 0 and examined for ear-swelling responses. CRA (●) or DMSO alone (○) was injected intraperitonially on days 0 and 1 (mean ± SD, n = 5). All animal experimental data shown in this figure are representative of at least 3 independent experiments producing similar results.