Response to Comment on "Tumor-initiating cells establish an IL-33-TGF-{beta} niche signaling loop to promote cancer progression"

Kamphuis et al. argue that macrophages accumulated in the proximity of tumor-initiating cells do not express the high-affinity immunoglobulin E receptor FcRIα. Although we cannot exclude the possibility of nonspecific binding of anti-FcRIα antibody (clone MAR-1), we provide evidence that macrophages in squamous cell carcinomas express FcRIα and that IL-33 induces FcRIα expression in bone marrow cell–derived macrophages.