Chemokines are important in leukocyte homeostasis, inflammation, angiogenesis, and metastasis. Here, the molecular diversity of chemokines present in ovarian carcinoma was studied by purifying the proteins to homogeneity from ascitic fluid. Biologically active intact CCL2 and processed CXCL8, CCL3, and CCL18 isoforms were recovered. CCL7 and CCL20 were also purified, but their levels were 10-fold lower compared with CXCL8, CCL2, and CCL3 and even 100-fold lower than the amounts of CCL18 isolated. In ascitic fluids from patients with ovarian carcinoma (n ؍ 12), significantly higher levels of CXCL8 and CCL18 (2.0 versus 0.7 ng/ml (p ؍ 0.01) and 120 versus 44 ng/ml (p ؍ 0.0002), respectively) were detected compared with those in nonovarian carcinoma patients (n ؍ 12). In contrast to CXCL8, CCL18 was not inducible in carcinoma cell lines. Immunostaining showed CCL18 expression in tumor-infiltrating cells with monocyte/macrophage morphology but not in the ovarian carcinoma cells. Our data demonstrate that biochemically heterogenous but biologically active forms of several chemokines are present at different concentrations in ovarian carcinoma ascitic fluid. This points to a delicate balance of chemokines in epithelial ovarian cancer and to a potentially major role for CXCL8 and CCL18 in this tumor.Chemokines are small chemotactic cytokines that are structurally divided into C, CC, CXC, and CX 3 C subgroups according to the positioning of conserved cysteine residues (1). This classification corresponds only in part with a biological division of chemokines in groups that selectively attract specific subtypes of leukocytes. For example, CC chemokines are capable to activate and chemoattract multiple leukocytic cell types. Alternative attempts were made to classify chemokines as inflammatory chemokines (i.e. inducible proteins that attract leukocytes to sites of inflammation) or constitutively released homeostatic chemokines that regulate leukocyte homing in the lymphoid system (2). Besides their function in leukocyte migration, chemokines are involved in other normal or pathological processes, like hematopoiesis, angiogenesis, cancer growth, and metastasis (3, 4). This indicates that our understanding of the exact role of a number of chemokines remains limited. As a consequence, a systematic chemokine and chemokine receptor nomenclature based on protein structure rather than on function has been introduced recently (3), despite the fact that not all chemokines nor all their receptors have been identified. Indeed, for some recently cloned chemokines such as CCL18/ pulmonary and activation-regulated chemokine (PARC) 1 (5), the regulated production and function of the natural protein has not yet been investigated in detail, and its agonistic receptor remains unknown.Chemokines are produced by a variety of cell types including leukocytes and cancer cells (6, 7). Tumor-derived chemokines are important for the characteristic recruitment of leukocytes, such as tumor-associated macrophages (TAM) and lymphocytes, to the ...