Murine granulocytes control human tumor growth in SCID mice

Severe combined immunodeficient (SCID) mice generally do not reject allogen eic or xenogeneic organ grafts and represent a unique model for investigati ng in vivo the behaviour of both normal and neoplastic human cells. However , cells from human primary tumors often do not grow in SCID mice. We have p reviously shown that the major reaction of SCID mice to the engraftment of human peripheral blood leukocytes is a massive granulocyte recruitment into the site of transplantation. In this study, we have investigated the role of murine granulocytes in the control of human tumor cell growth in SCID mi ce. We report here that murine granulocytes infiltrate and delimit the huma n tumor mass and that treatment of SCID mice with anti-murine granulocyte a ntibody markedly improves the growth of human tumor cell lines of different origin through suppression of the host granulocyte reaction. This finding provides a new tool for improving the human tumor take in SCID mice, thus o pening new perspectives for a practical in vivo preclinical test of anti-tu mor strategies. Moreover, this study, even with the limits of the known nat ural reaction against xenotransplants, further supports the importance of g ranulocytes in the control of tumor take and growth. Int. J. Cancer 87:569- 573, 2000. (C) 2000 Wiley-Liss, Inc.