We compared the expression of human α- and β-defensins by various human tissues. mRNA for α-defensins HNP1-3, abundant in bone marrow, was detected in peripheral blood leukocytes, spleen and thymus by RT-PCR, which revealed α-defensins HD5 and HD6 only in the small intestine. In contrast, the pancreas and kidney expressed high levels of hBD-1 and lower levels of this β-defensin were found in many organs by RT-PCR (salivary gland > trachea > prostate and placenta > thymus, testis, small intestine), hBD-1 mRNA was produced constitutively by cultured normal human epithelial cells derived from the trachea, bronchi, small airways and the mammary gland. These largely non-overlapping tissue distributions of human α- and β-defensins suggest that hBD-1 may be positioned to defend epithelial cells and mucosae from infection, whereas expression of HNP1-3 in neutrophils and HD5 and HD6 in Paneth cells allows these α-defensins to participate in systemic and small intestinal host defenses, respectively.
Zhao, C., Wang, I., & Lehrer, R. I. (1996). Widespread expression of beta-defensin hBD-1 in human secretory glands and epithelial cells. FEBS Letters, 396(2–3), 319–322. https://doi.org/10.1016/0014-5793(96)01123-4