Sequential determination of circulating immune complexes during progressive and regressive phases of mouse...

Circulating immune complexes were determined by 125I-C1q-binding and Raji cell-binding sequentially during distinct phases of progression and regression of a weakly immunogenic murine tumour. No increase in levels of circulating immune complexes was found at any time during tumour development, although reference complexes formed between tumour cell membrane antigens and a murine histocompatibility antigen-directed alloantibody were easily detected by both tests. These findings parallel the absence of humoral antibody during tumour development but are in some contradiction to the pronounced B cell proliferation which was observed in this tumour model. The results add evidence for a more critical evaluation of the role which levels of circulating immune complexes might play in tumour diagnosis and prognosis.