Promotion of anti-keyhole limpet hemocyanin IgM and IgG antibody productions in vitro by red bell pepper extract

Red bell pepper (Capsicum annuum L.), eaten as vegetables, is a rich source of vitamin C and E, provitamin A, beta-carotene, and numerous phenolic compounds. Its antioxidant, antimutagenic and anti-inflammatory properties have been reported. However, scientific report on its immunomodulatory activities is scarce. We, for the first time, reported the promotion of polyclonal immunoglobulin (Ig) M production by red bell pepper extract (RBPE). The present study was aimed to investigate the activity of RBPE on keyhole limpet hemocyanin (KLH)-specific IgM and IgG antibody productions in vitro. Anti-KLH antibodies, anti-KLH IgM secreting cells, and viable cells were determined by ELISA, ELISPOT and MTT assays, respectively. RBPE (0.75 and 1.5 mg/mL) significantly enhanced the production of anti-KLH IgM in cultured splenocytes of non-immunized (189 and 184%, respectively) and immunized mice (145% at 1.5 mg/mL). The same doses promoted the formation of anti-KLH IgM secreting cells 185 and 232%, respectively. Moreover, RBPE (0.375 mg/mL) augmented anti-KLH IgG production by 145 and 157% in cultured splenocytes collected from mice 1 and 3 weeks after a booster injection. Thus, RBPE induced KLH-specific antibody productions. The findings of the present study suggest that consumption of RBPE or vegetables may be beneficial to strengthen humoral immune responses. (C) 2013 Elsevier Ltd. All rights reserved.