The main objective of the study is to analyse at the healthy voluntary subjects the systematic immunizing answer induced after nasal, oral or sublingual administration of the CTB from blood samples - the lymphoid "compartment" the most accessible at the man- from saliva and from nasal wash. The immune response after administration of the CTB By sublingual way should be comparable in that of two other ways in term of intensity of the response, however, with a different IgA / IgG report.