MicroRNAs are expressed and processed by human primary macrophages

Macrophages are crucial to host defense, functioning in innate and cell-mediated immunity. MicroRNAs (miRNAs) are small non-coding RNA molecules that repress transcription and protein production. Little is known about miRNA expression in primary human macrophages, or about how macrophage miRNAs contribute to both normal macrophage function and to the pathogenesis of disease in humans. Using Western blot analyses, we demonstrated the production of miRNA machinery proteins by human primary macrophages. Using two different miRNA array techniques, we identified 119 miRNAs expressed by human primary macrophages, including hsa-let-7a, miR-16, -23a, 30b, -103, -146a, -212, and -378 and validated them by quantitative RT-PCR. Our findings provide a knowledge base to which macrophage miRNA expression in organ-specific macrophages or disease processes may be compared in humans.