Upper respiratory tract is the major site of antibody production in mycoplasmal induced chronic respiratory disease.

Chronic respiratory disease in rats, resulting from Mycoplasma pulmonis infection, provides a unique opportunity to study the interactions between systemic and mucosal immune systems in a naturally occurring infection of the respiratory tract. In the present studies, an ELISPOT assay specific for the determination of numbers of anti-M, pulmonis antibody forming cells (AFC) was developed. Using this assay, the numbers of IgG, IgM, and IgA AFC in respiratory and nonrespiratory associated lymphoid tissues were determined. The lymphoid tissues associated with the upper respiratory tract, which includes nasal passages and lymph nodes which drain various portions of the upper respiratory tract, were the major site of antibody production. Antibody responses within the lung were minimal. IgM and IgA were the major antibody isotypes produced in each of the tissues examined.