Serum immunoglobulin abnormalities in patients with respiratory tract disease.

Serum immunoglobulin concentrations in patients representing four different categories of respiratory diseases are compared with each other and with an age related group of healthy voluntees. Natural immune stimulation of the respiratory tract results in a significant rise in serum IgA and IgG but not IgM. A comparision with their respective normal serum control values further indicates that the major increase is within the IgA class and, that although significant, the rise in IgG is relatively minor. The preferential serum IgA response observed in the patient population suggests that bronchial associated lymphoid tissue in the diseased lung is an important source of circulating IgA.