Peritoneal macrophages from adjuvant arthritic rats enhance tumour cell growth in vitro

Summary Peritoneal macrophages from rats with adjuvant arthritis enhance the incorporation of³H-thymidine in 2 tumour cell lines in vitro. Maximal enhancement is found during the development of the secondary lesions, and it is suggested that the immunologic commitment of the macrophages could interfere with their regulation of tumour cell proliferation in vivo.Acknowledgments. The authors thank Drs P.F. Engel and M.P. Andreasen from the Finsen Institute, Copenhagen, for their gift of tumour cells and Ms E. Greve Petersen, Ms B. Hasselriis and Ms F. Norris for excellent technical assistance.