title: Vitamin C acts indirectly to modulate isotype switching in mouse B cells.
abstract: Vitamin C, one of essential micronutrients, has been reported to modulate the humoral immune responses in some mammals. We investigated whether vitamin C might modulate this response in mice by directly affecting B cells. Splenic B cells were isolated and activated by CD40- and B cell receptor-ligation in vitro. The cells were cultured with a pretreatment of vitamin C from 0 to 1 mM of concentrations. Vitamin C slightly increased apoptosis of B cells dose-dependently and behaved as an antioxidant. We found that in vivo administration of vitamin C by intraperitoneal injection affected isotype switching as previously reported: the titer of antigen-specific IgG1 antibody was decreased, while that of IgG2a was unaffected. Somewhat different from those observed in vivo, in vitro exposure to vitamin C slightly decreased isotype switching to IgG1 and increased isotype switching to IgG2a. Pretreatment with vitamin C in the safe range did not affect either proliferation of cultured B cells or the expression of CD80 and CD86 in those cells. Taken together, in vivo results suggest that vitamin C acts to modulate isotype switching in the mouse. However, because of our in vitro results, we suggest that the modulation exerted by vitamin C in vivo is by indirectly affecting B cells, perhaps by directly influencing other immune cells such as dendritic cells.
authors.affiliation: Department of Anatomy and Tumor Immunity Medical Research Center, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Ami
authors.initials: A
authors.lastname: Woo
authors.forename: Jin-Hee
authors.initials: JH
authors.lastname: Kim
authors.forename: Young-Joo
authors.initials: YJ
authors.lastname: Jeong
authors.forename: Hyung Gun
authors.initials: HG
authors.lastname: Maeng
authors.forename: Yong-Taek
authors.initials: YT
authors.lastname: Lee
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Kang
authors.forename: Wang Jae
authors.initials: WJ
authors.lastname: Lee
authors.forename: Young-Il
authors.initials: YI
authors.lastname: Hwang