CD 1d knockout mice exhibit aggravated contact hypersensitivity responses due to reduced interleukin‐10 production predominantly by regulatory B cells

Conflicting observations have been reported concerning the role of CD 1d‐dependent natural killer T ( NKT ) cells in contact hypersensitivity ( CHS ), supporting either a disease‐promoting or downregulatory function. We studied the role of NKT cells in CHS by comparing the immune response in CD 1d knockout ( CD 1d KO ) and wild‐type (Wt) mice after contact allergen exposure. For induction of CHS , C57 BL /6 CD 1d KO mice ( n = 6) and C57 BL /6 Wt mice ( n = 6) were sensitised with 1% (w/v) dinitrochlorobenzene ( DNCB ) or vehicle for three consecutive days and subsequently challenged with a single dose of 0.5% DNCB (w/v) on the ears fifteen days later. We demonstrate that CD 1d KO mice, as compared with Wt littermates, have more pronounced infiltration of mononuclear cells in the skin (29.1% increase; P