Cellular immunity and complement levels in hosts with brain tumours.

As a major defence mechanism against cancer, host immunological surveillance is composed of a cellular immunity as well as humoral immunity including antibody and a complement system. In the course of the progress of brain tumours alone, serum complement level (CH 50) as a humoral immunological factor and the tuberculin skin reactivity as an index of cellular immune activity, were serially measured in brain tumour patients. One hundred and fifty-seven cases of brain tumours, including 75 cases of glioma, 25 benign tumours, and 42 metastatic tumours, were examined. Most cases of benign tumour belong to stage I oder II, in which both tuberculin reaction and complement are active. Many cases of glioblastoma and metastatic tumour belong to stage III; that is, they show negative tuberculin reaction and increased complement activity. The relation of immunological response to the tumour size and the clinical severity in patients with gliomas is revealed by the fact that complement titres rise in accordance with the degree of progress of the tumour and a negative tendency in the tuberculin reaction runs parallel to this. All cases of glioma, even in the terminal stages, remain in stage III. On the other hand, cases of metastatic tumour progress to stage IV and V, in which the tuberculin reaction is negative and complement titres decrease. The combined results of elevated complement level and depressed status of tuberculin reaction in patients with gliomas may be explained by the concept that complement activity rises to compensate for depressed cell-mediated immunity, in order to preserve the activity of the biophylaxis mechanism against cancer.