Experiences with lymphocyte immunotherapy in experimental tumor systems

Despite few laboratory studies concerning the effects of sensitized lymphocytes on experimental tumor growth, interest in the use of such cells for the treatment of human neoplasms is increasing. The present study presents findings concerning the effects of sensitized isologous, allogeneic, and xenogeneic lymphocytes on transplanted small (5 mm) methylcholanthrene (MC)‐induced and spontaneous mammary tumors in isogeneic hosts and on the growth of cells from such tumors inoculated into appropriate syngeneic recipients. Such lymphocytes were either those circulating in blood and lymph or those obtained from lymph nodes, spleen, or thymuses of tumor‐sensitized animals. In a number of studies, zymosan was employed alone and with lymphocytes. Despite a variety of therapeutic regimens, these studies have been disappointing in that they have failed to convincingly demonstrate that the employment of such cells in the model systems utilized have influenced tumor growth either of an inoculum of cells or of a small‐growing tumor. Of the many experiments carried out, only one using sensitized isologous circulating lymphocytes in animals harboring MC‐induced tumor cell inocula was effective in this regard. Allogeneic and xenogeneic cells were uniformly ineffectual. Consideration is given to these findings in relation to those of other investigators, and it is concluded that more experimental evaluation of the use of immune lymphocytes is in order prior to the extensive application of their clinical use.