Distribution of alpha 1-antitrypsin in normal, granuloma, and tumor tissues in rats.

Purified rat alpha 1-antitrypsin and albumin were radiolabeled, and their distribution and catabolism in various tissues were studied in rats with inflammatory granuloma or transplanted sarcoma. Intravenously administered labeled alpha 1-antitrypsin accumulated remarkably in extravascular spaces of the granuloma or sarcoma tissues. Among the normal organs examined, the lung preferentially incorporated alpha 1-antitrypsin. Furthermore, most of the alpha 1-antitrypsin accumulated in these three tissues remained in a TCA-precipitable form throughout the observation period. Since alpha 1-antitrypsin is incorporated in large amounts into inflammatory or tumor tissues, it could play a role in regulation of inflammatory processes or in controlling the proliferation of a tumor. The studies on TCA fractionation also suggest that liver and kidney provide the main sites for degradation of this protein. Although the accumulation of labeled albumin in granuloma and sarcoma was less marked, it showed essentially the same distribution and degradation pattern as alpha 1-antitrypsin in both morbid states.