Local IgA and IgG response to intratracheal immunization with Pseudomonas aeruginosa antigens

We have experimentally immunized rats intratracheally with sonicated Pseudomonas aeruginosa to develop a high antibody response systemically and locally. The systemic antibodies were measured by a standard enzyme-linked immunosorbent assay (ELISA) on serum samples, whereas the local antibodies were measured on eluates from paper discs containing saliva. High levels of IgA antibodies were elicited in saliva whereas only traces of IgG antibodies were detected; the opposite results were found in serum. The saliva disc method permits serial measurements from the same animal and therefore offers the possibility to follow post-immunization antibody responses.