Diffuse alveolar hemorrhage (DAH) is characterised by the presence of red blood cells and free hemoglobin in the alveoli and complicates a number of serious medical and surgical lung conditions including the pulmonary vasculitides and acute respiratory distress syndrome. In this study we investigated the hypothesis that exposure of human alveolar epithelial cells to hemoglobin and its breakdown products regulates chemokine release via iron and oxidant mediated activation of the transcription factor NF-B. Methemoglobin alone stimulated the release of IL-8 and MCP-1 from A549 cells via activation of the NF-B pathway, additionally IL-8 required ERK activation and MCP-1, JNK activation. Neither antioxidants nor iron chelators and knockdown of ferritin heavy and light chains affected these responses, indicating that iron and reactive oxygen species are not involved in the response of alveolar epithelial cells to methemoglobin. Incubation of primary cultures of human alveolar type 2 cells with methemoglobin resulted in a similar pattern of chemokine release and signaling pathway activation. In summary we have shown for the first time that methemoglobin induced chemokine release from human lung epithelial cells independent of iron and redox mediated signaling involving the activation of the NF-B and MAPK pathways. Decompartmentalisation of hemoglobin may be a significant pro-inflammatory stimulus in a variety of lung diseases.