Immunological studies on bronchial secretion. I. Antigenic relationship between bronchial secretion and serum: bronchial secretion constituents detected in human sera.

Rabbit anti-human bronchial secretion serum yielded, by double gel-diffusion, 5 precipitation bands with the homologous antigen. This anti-bronchial secretion serum reacting with 150 human sera (86 from patients with asthma, 17 from patients with tuberculosis, 25 from patients with other diseases and 22 normal sera) showed 1 to 3 precipitation bands in 136 sera, 4 precipitation bands in 13 sera and 5 precipitation lines in 1 serum. Precipitation bands with identity reactions were obtained when the anti-sputum sera reacted simultaneously with human sera and bronchial secretion. Identity reactions were also obtained when the anti-bronchial secretion serum absorbed with normal human sera reacted with bronchial secretion and human sera from six patients and one normal individual. The number of precipitation bands in some sera was not the same after 1 or 2 years. Based on these immunological data, the physiological concept of expectoration, according to which part of the bronchial secretion may be absorbed, was discussed.