Résumé
The present study was undertaken to investigate the role of calcium ions (Ca2+) in the induction and secretion of the dengue type 2 virus induced cytotoxic factor and the cytotoxin. This was done by using calcium channel blocking drugs such as verapamil, nifedipine or diltiazem hydrochloride. The production of cytotoxic factor was significantly reduced by treatment of dengue type 2 virus infected mice with verapamil. Similarly, a dosedependent inhibition of the secretion of cytotoxic factor was observed, when spleen cells of the virus-primed mice were treated in vitro with the 3 calcium channel blockers. The production of cytotoxin by macrophages was abrogated by pretreatment with calcium channel blockers but had little effect on its secretion as shown by treatment of macrophages with verapamil at 1 h after the induction to later periods up to 18 h. The findings thus show that in the induction of both the cytokines Ca2+ plays a critical role; on the other hand it is required for the secretion of the cytotoxic factor but not for that of the cytotoxin.
Résumé
In this study,we presented data that K562,YAC-1 and LAC-1 cells or tumor-membrane-associated protein could stimulate BCG-treated macrophages from BALB/c mice to produce cy-totoxic factor (M?-CF). CF-inducing activity of K562 membrane or tumor cells remainde afterheat-treated at 100℃ for 20 min, but decreased by trypsin digestion or NaIO_4 oxidixa-tion. Thisactivity was also hibited by ConA or D-Man, but not by Gal. and Giu. The results suggested thatgiycoprotein containing D-Man on tumor cell surface was responsible for traggering M?s toproduce CF.
Résumé
Effects of the activiating and stimulating signals on the production of TNF-like cytotoxic factor (s) [Macrophage-derived cytotoxic factor(s), M?-CF] were investigated. Although activiating signals (Calcium ionophore A23187 and Macrophage-activiating factor, MAF) did not induce the production of M?-CF by themselves, they were significantly synergistic in the production of M?-CF induced by stimulators. Upon exposing to Iipopolysaccharide (LPS) M?-CF appeared in culture supernatant within 2 hrs, reached a peak after about 8 hrs and then declined gradually. In addition to LPS, opsonized zymasan A and several tumor cell lines also induced M?-CF production. whereas latex beads and normal allogenic spleen lymphocytes had no effect on the production. Finally the stimulating role of LPS, zymosan A and tumor ceils could not be mimicked by protein kinase C (PKc) activiators (phorbol myristate acetate, PMA and calcium ionophore A23187). These results suggested that the induction of M?-CF production be stimulus-specific and PKc-independent.
Résumé
The cellular sources of leukoregulin (LR) and lymphotoxin (LT) from human peripheral blood leukocytes or spleen cells were examined The ratios of LT activity to LR activity in lymphokine preparations from different individuals were not constant but varied over 640-fold, suggesting that LR and LT activities were mediated by distinctly different entities.Purified LR was used to examine the relative susceptibilities of human or mice cells to LR.Most human tumor cells were very sensitive to LR while human normal cells and mice normal or tumor cells were less sensitive or resistant.Crude preparations of human interferon (Hu IFN)-? or Hu IFN-? were more cytotoxic to human tumor cells than partially purified natural Hu IFN-? or highly purified rHu IFN-?D, and crude or purified LR were more cytotoxic to human tumor cells than Hu IFN-? Hu IFN-?.Hu IFN-? activity but not cytotoxic activity could be removed from preparatons containing Hu IFN-?,LR and LT activities with the aid of monoclonal antibody to Hu IFN-?. Natural killer cytotoxic factor (NKCF) supernatants from the co-culture of human spleen cells and NK susceptible cell line K562 or Molt-4 were strongly cytotoxic to various tumor cell lines.The NKCF activity was completely adsorbed after incubation with Molt-4 cells and completely inactivated by incubating at pH2 for 24 h.The putative receptor for LR or LT was studied using adsorption assay.The present study reveals that human LR activity can be adsorbed from crude LR supernatants by incubation with native or formalin-treated K562 or SMMC-7721 cells at 37℃ or 4℃; LT activity can be adsorbed with L929 cells.Therefore, LR appears to be a cytotoxic/cytostatic factor that is distinct from LT, 1FN and NKCF.