Immune Responses against Streptococcus pyogenes in Human Palatine Tonsils

AbstractWe investigated cellular immunity against Streptococcus pyogenes in human tonsils by measuring antigen‐specific immunoglobulin‐secreting cells and the production of cytokines from CD4+ T cells in response to M proteins. The incidence of S pyogenes in tonsils was significantly higher in patients with recurrent tonsillitis (RT) than in patients with tonsillar hypertrophy (TH). M protein‐specific immunoglobulin A (IgA) and immunoglobulin G spot‐forming cells were increased in patients with RT compared with patients with TH. In RT the number of M protein‐specific IgA spot‐forming cells was significantly greater in the S pyogenes‐negative subjects than in the S pyogenes‐positive subjects. Proliferation of CD4+ T cells and production of interferon‐gamma (IFN‐γ) and interleukins−2,− 4, −5, and −6 (IL‐2, IL‐4, IL‐5, and IL‐6) from those T cells were observed in response to M protein. The concentrations of IFN‐γ and IL‐4 were higher in RT than in TH. These findings suggest thatS pyogenes is associated with the pathogenesis of RT and that immune responses against M protein may play an important role in preventing the colonization of this bacteria in tonsils.