A study was made on five cases of multiple Bowen's disease observed in former workers of a poison gas factory which was in operation from 1929 to 1945 at Okunojima, Hiroshima, Japan. The age of these patients ranged from 63 to 70 years with an average of 66 years. The period engaged in poison gas production averaged 9.3 years. The averaged interval from initiation of the poison gas production to determination of diagnosis of Bowen's disease was 39.2 years. All five patients were engaged in the production of mustard gas which is a vesicant poison gas and an alkylic agent. The number of lesions of Bowen's disease in a patient ranged from 2 to 7. Ten lesions were found on the trunk and 13 on the extremities. In addition, there were numerous pigmented and depigmented spots and hyperkeratotic papular eruptions on the skin of all patients. There are no reports in the literature on Bowen's disease caused by mustard gas. The results of this study strongly suggest that multiple Bowen's disease in workers formerly engaged in the production of poison gas is caused by exposure of mustard gas experimentally demonstrated to be a carcinogen.

The magnitude of antigen-induced histamine release from actively sensitized rat tissues in vitro was compared with the amount of specific reagin in the serum. There was no quantitative correlation between either, suggesting that the antigen-induced histamine release from sensitized tissues might depend on the ability of sensitized target cells to release histamine. In addition, the magnitude of antigen-induced histamine release was different in each tissue of sensitized rats. This also suggested that there might be some differences in the ability of sensitized target cells in each tissue to release histamine by antigen.

Intradermal skin tests and in vitro antigen‐induced histamine release from leucocytes were carried out using mite, house dust and candida allergens in 49 patients with chronic urticaria in whom the cause was not identifiable from the history. None of them had other atopic diseases. Among the 49 cases, the number of patients who gave positive skin reactions to different allergens was as follows: mite, 24; house dust, 18; candida, 17. Significant histamine release from leucocytes by mite antigen was observed in 8 out of 12 patients who had 2+ or 3+ skin reactions. The present results suggest that mite, house dust and candida allergens may play a role in chronic urticaria, and especially that the mite may be one of the possible allergens in chronic urticaria.

A tissue plasminogen activator was extracted from skin lesions with allergic vasculitis and purified by successive column chromatography on Sephadex G-200, DEAE-cellulose, Hydroxyaptite-cellulose and polyacrylamide gel electrophoresis. By these procedures, 160 micrograms of enzyme with a specific activity of 843.8 international units/mg protein was obtained from 5 g of original skin. The purified material was homogeneous as ascertained by sodium dodecyl sulfate polyacrylamide gel electrophoresis and had an apparent molecular weight of 110,000 as measured by gel filtration on Sephadex G-200. Its identity with human urokinase was investigated and was found to possess the same plasminogen activator activity as that of urokinase. It had high amindolytic activity, but only slight N-alpha-acetyl-glycyl-L-lysine methyl ester esterolytic activity. This tissue plasminogen activator was confirmed to be immunologically identical to human urokinase.

SummarySix different plasmins were prepared by incubating human plasminogen with various amounts of streptokinase or urokinase. It was confirmed that the six different plasmins possessed similar caseinolytic activities, and the inhibitory effects of α 1-antitrypsin on caseinolytic activities of the six different plasmins were all the same. On the other hand, interactions between the six different plasmins and α2-macroglobulin were complicated. Plasmins activated by cleavage of plasminogen were almost immediately or effectively inhibited by α2-macroglobulin. However, plasmin activated by complex formation of plasminogen with streptokinase was not so immediately or effectively inhibited by α2- macroglobulin. It was supposed that the difference between these two results on the interaction between plasmin and α2-macroglobulin might be due to the difference in molecular form of plasmin. In the present study, it was also confirmed that streptokinase or urokinase, in free form in the reaction mixture, interfered with the interaction between plasmin and α2-macroglobulin. The cause for such interference was discussed.