Impairment of Phytohaemagglutinin-Induced Blastic Transformation in Lymphnodes from Thymectomized Mice

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Abstract
In mice, the injection of phytohemagglutinin (PHA) into a footpad leads to proliferation of large pyroninophilic cells in the draining lymph nodes. Automated analysis of the cell-size distribution in suspensions of lymphnode cells, using an electronic particle counter, constitutes a simple and rapid method of quantitating the blastoid response in stimulated lymphnodes. The calculated transformation rates displayed a close correlation with the weight, thymidine incorporation and histological appearance of the organs at various times after the administration of PHA. Following neonatal thymectomy or following adult thymectomy combined with whole-body irradiation, the reactivity of the lymphatic tissue to PHA was largely abolished. Thymus grafting succeeded in preventing the effects of thymectomy. PHA may possess an immunological mechanism of action. Determination of the transformation rates in PHA-stimulated lymphnodes furnishes a new model for ascertaining the immunological reactivity of an organism.