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Over-expression of the folate receptor (FR) has been shown on the vascular side of cancerous cells including those of the breast, ovaries, testes, and cervix. However, FR over-expression has not yet been explored fully in melanoma. We hypothesized that folate receptor is over-expressed on melanoma and that a novel folate-conjugated immunoglobulin G (F-IgG) would bind the FR to target melanoma cells for lysis by natural killer (NK) cells. Folate receptor expression was confirmed in the Mel-39 (human melanoma) cell line by flow cytometry and immunoblot analysis, using KB (human oral epithelial) and F01 (human melanoma) as a positive and negative control, respectively. FR positive and negative cell lines were coated with F IgG or control immunoglobulin G (C-IgG) in the presence or absence of cytokines in order to determine NK cell ability to lyse FR-positive cell lines. NK cell activation was significantly upregulated and lysis of Mel 39 tumor cells enhanced following treatment with F IgG, as compared to C-IgG at all effector:target (E:T) ratios (p<0.01). This trend was further enhanced by the addition of interleukin-12 (IL-12). NK cell production of cytokines such as interferon-gamma (IFN-γ), macrophage inflammatory protein 1 alpha (MIP-1α), and regulated on activation normal T-cell expressed and secreted (RANTES) were also significantly increased in response to IL 12 stimulation and F IgG coated Mel 39 target cells, as compared to controls (p<0.01). In contrast, F-IgG did not bind to F01 (FR-negative cell line) and had no significant effect on NK cell lysis or cytokine production. This research indicates the potential use of F-IgG for its ability to induce an immune response from NK cells against FR-positive melanoma tumor cells which can be further enhanced by the addition of cytokines.