A morphological and quantitative study of tumor blood flow. I. During growth and immune rejection

We have used serial microangiography and radioactive 133 Xe to study microvascular morphology and quantify blood flow in Walker 256 carcinomas implanted in rat tails during growth and immune rejection. No previous angiographic/quantitative studies during immune rejection are reported. Two tumor groups were identified. Group A grew rapidly, with a two- to six-fold increase in blood flow, and caused death in 10 days. Group B grew more slowly, and increased blood flow two to four times. At 6 to 8 days postimplant the B tumors diminished in size; blood flow decreased and extensive lymphocytic infiltration developed. By 21 days all evidence of the tumor had disappeared. The rejection appears to be cell-mediated, and the high incidence (65-70%) to be related to the number of tumor cells and/or presence of accumulated antigen in the innoculum. Microangiographic changes during immune rejection were specific, and included marked tortuosity of feeding vessels and a "ghostlike" fading out of tumor vessels, quite unlike the appearance of necrosis.