The vast majority of patients with active Hodgkin's disease display a defect in cell-mediated immunity. The defect is progressive, and in the patient with advanced disease it contributes to the variety of common bacterial and unusual viral, fungal, and protozoal infections60 to which these patients are prone. In experimental animals, small lymphocytes of thymic origin are concerned with cell-mediated immunity, and the deficiency of the thymectomized animal closely resembles that of the individual with Hodgkin's disease.61,62 The class of immune reactions mediated by antibody is relatively unimpaired, in Hodgkin's disease.
Cell-mediated immune responses include bacterial (delayed) hypersensitivity, contact sensitivity, graft vs host phenomena, and the homograft reaction. The very use of the word anergy to denote a defect in cellular immunity in man attests to the imperfect and qualitative nature of tests available to evaluate this type of immunity. Methods of assessing delayed hypersensitivity are listed in Table