Chapter 7: The Iga Antibody System

Abstract

This chapter presents evidence that a local antibody system exists, that IgA is the immunoglobulin involved, and that there is biological advantage to such a system. By uniting the fragments of evidence into a general concept, the chapter suggests areas for additional studies. Viewing this system in functional and developmental perspectives, it is considered as a model for analysis of genetic control of development, transport of protein molecules, and the question of intimate relationship between man and his microbial flora in health and disease. Evidence has been presented that the IgA system is the last to develop both phylogenetically and ontogenetically, perhaps reflecting an adaptation of the immune system to terrestrial life. The evidence that particular antibodies are produced locally, that IgA is produced locally, and that these two may be one and the same response to a local stimulus, has been examined. Examination of the clinical course of persons lacking capacity to produce IgA has shown that many of these persons reveal a biological handicap. In combination with the demonstration of a specific transport mechanism for IgA, and of independence of IgA from the complement system, these pieces of evidence suggest that IgA is the immunoglobulin involved in a local antibody system.