A morphometrical analysis of lymph node responses to tumors of different immunogenicity

An immunogenic tumor and a nonimmunogenic tumor were used in C57BL/Ka and CBA/Rij mice, respectively, in a study in which lymph node morphology was quantitatively measured. Lymph nodes were cut in semiseries, and a morphometrical analysis was done on the paracortical and cortical areas as major parts of the active lymph nodes. These parameters could be expressed with confidence in both absolute and relative numbers, since a strong correlation existed between the weight of lymph nodes and the summated surface areas. To determine whether the regional lymph node plays a major role in this response, we performed similar analyses of two nonregional lymph nodes. It was observed that immunogenicity, defined as the ability to evoke an immune response that significantly influences tumor cell take and tumor cell growth, was not relevant in evoking a morphologically evident response. In absolute numbers, the response evoked was strongest in the regional lymph nodes in both systems. However, the percentages of paracortical and cortical areas in the lymph nodes reacting were not essentially different from one node to another during the growth of both tumors. This observation was confirmed by an analysis of variance. These findings suggest that great caution must be exercised when one is interpreting morphological lymph node changes as evidence of an influence of immunological reactions on tumor cell growth.