However, the expression of IL-33 by the tumours appeared to prevent the accumulation of these immune-suppressive cells, and promoted intensive infiltration by CD68+ tumour-associated macrophages (Fig. 5i–k) and neutrophils (Fig. 5l–n) in IL-33-expressing A9 tumours compared to unmodified A9 tumours. Here, IL33 is linked to neoplasm.