Mycobacterium bovis bacillus Calmette-Guerin (BCG) induces human CC- and CXC-chemokines in vitro and in vivo

Both CC- and CXC-chemokines are known to be potent leucocyte activators and chemoattractants and play important roles in inflammatory responses. However, chemokine response to bacillus Calmette-Guerin (BCG) infection remains incompletely defined. In this study, we investigated human CC- [macrophage-derived chemokine (MDC), monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1 alpha and eosinophil chemoattractant activity (eotaxin)] and CXC-interferon-inducible protein (IP)-10 chemokine production in response to BCG stimulation. BCG efficiently induced all chemokines tested in the urine of four bladder cancer patients undergoing intravesical BCG immunotherapy. The peak urinary chemokine responses occurred generally between the fourth and sixth weekly treatment, except eotaxin, which was less predictable. To evaluate the effect of BCG on induction of chemokines in vitro, urothelial cell lines and peripheral blood mononuclear cells (PBMCs) were used. Although BCG induced no or marginal chemokines from urothelial SV-HUC-1, RT4 and T24 cells, BCG-derived cytokines [interleukin (IL)-1 beta, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha] induced all chemokines tested except eotaxin from these cell lines. BCG also efficiently induced all chemokines tested except eotaxin from PBMCs of both BCG-naive and BCG-vaccinated subjects. MCP-1 and MIP-1 alpha emerged at 4-5 h post-BCG exposure (early chemokines); IP-10 elevated at day 1 and peaked at day 2 (intermediate chemokine); and MDC elevated at day 1 and peaked at day 7 (late chemokine). This kinetic pattern was paralleled with that of BCG-induced cytokines [early: TNF-alpha; intermediate: IL-6 and IL-10; and late: IFN-gamma and granulocyte-macrophage colony-stimulating factor (GM-CSF)]. Taken together, these results indicate that BCG directly or indirectly induces human CC- and CXC-chemokine production, which may represent one of the mechanisms by which BCG exerts its anti-tumour activity.