Role of host's antitumor immunity in exercise-dependent regression of murine T-cell lymphoma

We have reported that the ascitic growth of a transplantable T cell lymphoma of spontaneous origin, designated as Dalton's lymphoma (DL), is associated with a concomitant immunosuppression. We have also reported that progressive in vivo growth of DL resulted in an inhibition of macrophage functions. In present investigation we report that physical exercise by DL-bearing mice, on a treadmill on a daily basis for various time durations for 10 days, increased the life span along with an inhibition of tumor growth. A significant decrease in the volume of ascitic fluid and number of cells in the tumor was obtained in mice, which underwent exercise. DL cells obtained from exercised groups showed a decreased proliferation in vitro. An augmentation in the percent of cells showing apoptotic morphology and percent specific DNA fragmentation was observed, suggesting that physical exercise increased the incidence of apoptosis in tumor cells. Moreover, macrophages obtained from tumor-bearing mice, which underwent exercise training, showed an augmented tumoricidal activity and production of tumoricidal molecules like interleukin-1 (IL-1), tumor necrosis factor (TNF) and nitric oxide (NO). On the basis of this study it is suggested that the regression of tumor growth consequent to physical exercise training of tumor bearing host, may be due to an exercise-dependent augmentation of macrophage tumoricidal functions. Nous avons obervé que la croissance progressive d'un lymphome de cellule T d'origine spontanée désigné sous le nom de ‘lymphome de Dalton’ est associée à une immunodépression concomitante. Nous avons aussi observé que la croissance progressive du ‘Lymphome de Dalton’ résulte d'une inhibition des functions des macrophages. Dans la présente étude, nous avons observé que l'exercice physique chez les souris porteuses de lymphomas de Dalton sur un tapis roulant, quotidiennement pendant des temps variés et pendant dix jours augments lad durée de vie et permet une inhibitlion de la croissance des tumeurs. Une diminution significative du volume du liquide d'acide et du nombre de cellules dans la tumeur a été soumises à cet exercice. Les cellules de lymphome de Dalton obtenues à partir des groupes soumis à l'exercice ont montré une diminution de leur prolifération in vitro. Une augmentation du pourcentage de cellules montrant une morphologie apoptotique et un morcellement de l'AND spécifique a été observée, suggérant qu'un exercice physique augmente l'incidence de l'apo