IL4 and neoplasm: In contrast to its growth stimulatory effect on lymphocytes, IL-4 has been shown to have a modest but direct inhibitory effect on the growth of tumour cells of haematopoietic and nonhaematopoietic origin in vitro and in vivo, including those derived from human melanoma, non-Hodgkin's malignant B-lymphoma, and colon, renal, gastric, and breast carcinoma (Defrance et al, 1992; Gallagher and Zaloom, 1992; Morisaki et al, 1992; Toi et al, 1992, Obiri et al, 1993).