Fig. 5.

Leukocyte infiltration in established S180 tumors. s.c. tumors were established in WT mice, which then received AT of SR/CR leukocytes. Regressing S180 tumors were sectioned, fixed, and stained with hematoxylin and eosin 24 days after receiving AT of SR/CR leukocytes. (A) Tumor cells are surrounded by MΦ and an outer layer of neutrophils, whereas a surprising number of plasma cells are observed in the outermost layer. (B and C) At higher power, small, scattered islands of surviving tumor cells are observed surrounded by MΦ and PMNs, with plasma cells seen in the periphery. Areas of scar tissue formation with fibroblast proliferation were also noticed. T, S180 tumor; M, MΦ; PMN, neutrophil; p, plasma cell; f, fibroblast. The brackets in C delineate the layers of infiltrating leukocytes.