Immunofluorescent and Clinical Studies in Idiopathic Interstitial Pneumonia (IIP) and IP with Collagen Disease

Abstract

We examined 35 cases of IP. Of these of 25IIP cases and 10IP cases with collagen diseases were examined by direct immunofluorescene microscopy.
Immunoglobulin lining alveolar walls and capillaries in a granular pattern was demonstrated in 7 of 25IIP patients, but complement components were all negative. All 10 patients of IP with collagen diseases had immunoglobulin deposition and 5 demonstrated complement. Circulating immune complexes were present in 6 out of 7 cases. According to these results, circulating immune complexes may play a role in the pathogenesis of IP with collagen diseases.
The immunofluorescence-positive IIP cases showed a high frequency in young women compared with the immunofluorescent negative ones. Extrapulmonary symptoms were noticed more frequently. Serum immunoglobulin level and a positive rate of autoantibosies were higher, but no difference were seen in pulmonary function between two groups. Above all in bronchoalveolar lavage there was a trend towards increased numbers of lymphocytes and a complementary fall in the percentages of macrophages. From the results these cases seem to be similar to IP with collagen diseases. They might be classified in a subgroup located between IIP and IP with collagen diseases. On the other hand, the duration from the onset to biopsy or autopsy were shorter in the immunofluorescent positive cases than in the immunofluorescent negative. Type I findings on chest X ray film were more frequent and Ga accumulation on scintigrams was observed in the former group. Slight fibrosis and moderate or severe cellular thickening of alveolar walls, were also observed more frequently. These results may be evidence of a difference in stage or activity of the same disease. Steroid responders were also seen more frequently in the former group, therefore, immunofluorescence microscopy of the lung might give some information on steroid effects.