遅延型アレルギー感作リンパ球のcytotoxic factorに関する検討
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概要
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Studies were made to elucidate the mechanism of production of cytotoxic factor by sensitized lymphocytes in delayed-type allergy and the substantial entity of this factor in the chicken. Neonatally thymectomized or bursectomized chickens were immunized against Mycobacterium BCG, or human γ-globulin in Freund's complete adjuvant. The supernatants of cultures of sensitized splenic lymphocytes collected from them were examined for cytotoxic activities on chickembryo fibroblasts. The results obtained are as follows.1) Delayed-type hypersensitivity was induced in bursaless birds having the T cell system but lacking the B cell system, but not in thymectomized birds lacking the T cell system. Cytotoxic factor began to be produced about 6 hours after the corresponding antigen had been added to the culture of sensitized lymphocytes. Then it was produced intensively for about 24 hours. Thereafter, its production was suppressed probably due to the presence of a feedback mechanism. It was also found that this factor exhibited "autotoxic" activity on sensitized lymphocytes themselves in the culture continually for more than 48 hours.2) When sensitized lymphocytes were exposed to metabolic inhibitors, such as actinomycin D, puromycin, and 2, 4-dinitrophenol, the production of cytotoxic factor was markedly suppressed. This fact indicates that this factor is biosynthetized de novo in the sensitized lymphocytes and secreted into the extracellular medium.3) Experiments were carried out by the fractionation of cytotoxic factor by gel-filtration with Sephadex G 200, DEAE-cellulose column chromatography of the culture supernatant, degradation with trypsin, and ultrafiltration by the Diaflo membrane of the cytotoxic fraction. From the results obtained, it was confirmed that the cytotoxic factor was a substance of protein nature contained in the α-globulin fraction, and had a molecular weight ranging from 50, 000 to 100, 000.Discussion was made on the findings mentioned above in relation to some already known chemical mediators produced by sensitized mammalian lymphocytes, and on the biological significance of these findings in immune responses.
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