Among the cytokines studied, IL-4 activates collagen synthesis, promotes fibrosis progression, and inhibits inflammatory cytokines production.18 Its secretion occurs in response to microorganisms, prosthetic material, volumetric or pressure overload.19 In this study, elevated levels of IL-4 were found in patients treated with a mechanical prosthetic implant; however, this increase was not associated with prosthetic dysfunction, rheumatic heart disease, gender or the time to progress after PrVA placement. Here, IL4 is linked to rheumatic heart disease.