PHA and ConA lymphocyte response in normal, hyperplastic and neoplastic human thymus: morphologic and functional correlations.

In the present work the in vitro response to PHA and ConA was determined for thymus lymphocytes from normal, hyperplastic, and neoplastic conditions as well as for peripheral blood lymphocytes from normal control donors. Our investigation has revealed these results: (1) lymphocytes from normal thymus are less responsive to both mitogens than lymphocytes from peripheral blood and abnormal thymus. (2) Lymphocytes from thymic benign lymphoid hyperplasia show an increased response only to PHA regardless of the extent of hyperplasia. (3) Lymphocytes from thymic neoplasia display an increased response to both mitogens regardless of the histologic pattern of the tumor studied. (4) Thymic lymphocytes from patients with myasthenia gravis have a mitogenic response higher than that from thymic lymphocytes from nonmyasthenic subjects. (5) In patients with myasthenia gravis, lymphocytes from neoplastic thymus show a response to PHA higher than that observed for lymphocytes from hyperplastic thymus. It seems clear that two conditions maximally enhance mitogenic response of thymus lymphocytes: thymomas and myasthenia.