Cytokines as adjuvants for the induction of mucosal immunity

Safe nasal vaccines capable of promoting both mucosal and systemic immunity are needed for effective protection against bacterial and viral pathogens. While parenteral cytokine treatment could lead to unwanted toxicity, the n asal delivery route results in low but biologically active serum cytokine l evels. Interleukin (IL)-6, IL-1 and IL-12, which promote either Th2- or Th1 -type responses, respectively, also enhance systemic immunity to co-adminis tered antigens. The chemoattractants lymphotactin (Lptn), RANTES and defens ins also exerted adjuvant activity for systemic immunity when nasally admin istered with antigens. However, each cytokine or innate factor promoted a d istinct pattern of T helper cell responses and corresponding IgG subclass r esponse. Interleukin-12, IL-1, and the chemokines Lptn and RANTES promote m ucosal immunity. In contrast, nasal IL-6 and defensins failed to induce muc osal S-IgA Ab responses, suggesting that mechanisms more complex than T cel l activation and chemotaxis are required for the development of mucosal imm unity after nasal delivery of cytokines. (C) 2001 Elsevier Science B.V. All rights reserved.