Cell culture in vivo. II. Behavior of L-fibroblasts in diffusion chambers in resistant hosts.

The growth of L-fibroblasts in diffusion chambers implanted intraperitoneally in C3H mice was inhibited by "hyperimmunizing" the host with L-fibroblasts; no significant inhibition was found while reactions analogous to first-set and second-set rejections presumably were occurring in the host outside the diffusion chamber. The serum from "hyperimmunized" C3H mice contained a diffusible (soluble) factor(s) which, when injected into isologous mice, inhibited the growth of L-fibroblasts in diffusion chambers in these animals. These results are consistent with the hypothesis that a circulating growth-inhibitory factor(s), presumably an antibody, may play an important role in the rejection of fibroblast-type cells as well as leukotic-type cells.