Modulation of growth-stimulating and antitumor activity of macrophages by BCG and cyclophosphamide

Recently it has been shown that some tumours require macrophage-derived growth factors for in vitro and in vivo proliferation, as well as tumour growth stimulation by macrophages. Furthermore, it has been reported that several biological response modifiers (BRM) stimulated some growth factor production in macrophages. In the present study we tried to define whether some BRM can modulate production of macrophage-derived growth factors for stimulating tumour cells. Results obtained indicate that: 1) growth stimulating activity of macrophages may be co-expressed with antitumor activity; 2) growth stimulating activity could prevail over antitumor effects in the outcome of tumour cell/macrophage interaction in vitro; 3) Some BRM and antitumor drugs can modulate the balance between antitumor and growth stimulating activity of macrophages. It is therefore proposed that growth factors modulation assessment is necessary for new BRM characterization.