Effect of levamisole on autologous rosette-forming cells in nude mice

Levamisole depresses the number of autologous rosette-forming cells (ARFC) in the spleen of nude (congenitally athymic) mice. Intravenous administration of 2.5 mg/kg of levamisole produces maximal depression. This effect appears 15 h after injection and is transient, partially disappearing after 48 hr. Dexamisole is devoid of this depressing activity. Thymopoietin, a thymic hormone, is also shown to lower the level of autologous rosette formation. These results suggest a stereospecific interference of levamisole with the maturation of immature T-cell precursors in a manner resembling the action of thymic hormones.