The serum immunoglobulin levels of 110 patients with pulmonary tuberculosis hospitalized at our Hospital were assayed by single radial immunodiffusion technique and the correlation with immunoglobulin levels in the serum and several factors in pulmonary tuberculosis were investigated. The results were as follows:
1. In the average of the serum immunoglobulin levels of 110 cases, IgG levels were increased but IgM and IgA showed no definite tendency.
2. All immunoglobulin levels were increased in the cases with cavities or active lesions.
3. In the improved cases on the chest X-ray, IgM and IgA levels were decreased but IgG had no definite tendency. On the other hand, in the unchanged cases on the chest X-ray, IgG levels were increased. IgM levels were increased in the cases with infiltrative lesions but decreased in the cases with sclerotic lesions.
4. Generally, the tendency of increasing in the IgG levels was observed according to the activity of the tuberculous lesions. Of particular relevance was the fact that IgM levels as well as IgG had a relation to the activity of tuberculous lesions.
