Some plant polysaccharides are well known to possess immunostimulatory effects.Aloe vera possesses confirmed curative or healing actions. The aim of this study was to evaluate the effect of the administration of A. vera plant extract on cellular and humoral immune response in rabbits. 20 healthy male New Zealand white rabbits were randomly divided into five treatment groups: Groups consisted of: 1) control group (normal saline); 2) A. vera control; 3) vaccine control; 4) 50 mg A. vera extract + vaccine; 5) 150 mg A. vera extract + vaccine. The used vaccine was for myxomatosis. Blood samples were obtained at four time points: days 0, 7, 14 and 21 of the study. CD⁴⁺ and CD⁸⁺ lymphocytes frequency and serum immunoglobulin concentrations were evaluated. According to the results, oral administration of A. vera affected the composition of lymphocyte subsets and serum immunoglobulins positively. These findings demonstrated that A. vera may stimulate both cellular and humoral immune responses after immunization.

Key words: Aloe vera, cellular and humoral immune, immunization, rabbits.