Effect of Physical State and Route of Inoculation of Diphtheria Toxoid on the Formation of Nasal Secretory and Serum Antibodies in Man¹

To determine whether the physical state and route of inoculation of an antigen influence the appearance of IgA secretory antibody in nasal secretions, seven adult male volunteers were given fluid diphtheria toxoid and seven others alum-precipitated diptheria toxoid either intranasally or intramuscularly. Fluid diphtheria toxoid nose drops stimulated both nasal secretory and serum antibody production while nose drops containing alum-precipitated diphtheria toxoid failed to stimulate antibody production at either site. Intramuscular immunization with both types of toxoid stimulated serum antibody formation, but no secretory antibody formation followed the alum-precipitated toxoid. These results suggest that the physical state and route of administration of an antigen determine whether or not secretory IgA antibody is produced, and that a non-replicating antigen applied locally in the proper physical state causes a substantial local secretory antibody response.