Prevention of ultraviolet radiation-induced suppression of contact hypersensitivity by Aloe vera gel components

We have recently reported that Aloe vera gel contains small molecular weigh t immunomodulators, G1C2F1, that restore ultraviolet B (UVB)-suppressed acc essory cell function of epidermal Langerhans cells (LC) in vitro. In the pr esent study we evaluated the UVB-protective activity of G1C2F1 in vivo. Exp osure of the shaved abdominal skin of mice to 2.4 KJ/m(2) of UVB radiation resulted in suppression of contact sensitization through the skin to 41.1%, compared to normal unirradiated skin. Topical application of G1C2F1 immedi ately after irradiation reduced this suppression significantly. The percent age recovery of UVB-suppressed contact hypersensitivity (CHS) response was 52.3, 77.3, and 86.6% when the irradiated skin was treated once with 0.1, 0 .5, and 2.5 mg/ml of G1C2F1-containing cream, respectively. G1C2F1 did not show nonspecific stimulatory activity on CHS response. The present study, t ogether with the previous observation, show that Aloe vera gel contains sma ll molecular weight immunomodulators that prevent UVB-induced immune suppre ssion in the skin by restoration of UVB-induced damages on epidermal LC. (C ) 1999 International Society for Immunopharmacology. Published by Elsevier Science Ltd. All rights reserved.