Dental General 57f4102b It is likely that cell mediated immune reactions (delayed hypersensitivity) occur in periodontitis because subjects with periodontitis have A High levels of histamine in involved gingival tissue B IgG antibodies reactive with plaque bacterial antigens C Ttymphocytes sensitized to bacterial plaque antigens D High Levels of collagenase in gingival fluids High-Yield Explanation No explanation provided.