Discussion

Abstract

I found all of these presentations very interesting and some of them most provocative. I would like to speak first to Dr. Lehner’s presentation. One of the things that may be very important in the differences in the effects of antibodies of IgM, IgG and IgA type, in addition to the differences in, for example, their bactericidal capacity, is their distribution. If one injects IgM intravenously, then that is where it stays; it doesn’t go anywhere else. On the other hand, IgG injected intravenously is distributed intravenously as well as interstitially in tissues, and some of it can come out in the secretions. When we gave IgA i.V., especially to immunodeficient patients, we simply did not detect it in the secretions; IgA stays intravenously. So one wonders whether it would not have been germane for passive immunization to give the IgA orally. I think this translates into other approaches and I wanted to ask the question of any of the speakers whether anyone has immunized orally with antigen or infecting agent and then followed with a local stimulation? I think this would be the ideal way of getting local IgA immunity that might be in the right place. It may very well be that in the caries situation it is a complicated matter of the attachment and penetration. So if you want to get an effective IgA-mediated protection, you must interfere at the very first phase of the pathogenesis, and the IgG antibody may be involved at another stage.