Abstract: Objective The bactericidal/permeability-increasing(BPI) protein is an important protein expressed in some cells, which has bactericidal activity on gram-negative organisms. It is involved in the defense against gram-negative bacterial infections and binds to LPS with high affinity. Its expression profile in human tissues has been revealed by previous studies in our laboratory and other laboratories. But no reports about its expression profile in mouse, the most popularly used animal model were published. This study aimed to reveal the expression profile of BPI protein in various tissues from mice in physiological condition and by LPS stimulation. Methods BPI protein expression was detected with immunohistochemical staining using anti-muBPI polyclonal anti-serum. Pre-bleeding rabbit serum was served as negative control. Different tissues from mice treated with LPS(550 ng per mouse) and untreated mice were examined, including testis, small intestine, heart, liver, lung, spleen, kidney, bone marrow, peritoneal enterocoelia clysis(PECs) and bone marrow-derived dendritic cells(BMDCs). Results 1 Murine BPI protein is weakly expressed in testis, small intestine, kidney, bone marrow, PECs and BMDCs in control group(untreated with LPS), but its expression increased dramatically after LPS stimulation; 2 The expression of BPI protein could not be detected in liver and lung in control mice, but could be detected after LPS stimulation; 3 Expression of BPI protein could not be detected in the other examined tissues, no matter with or without LPS stimulation. Conclusion This study has successfully revealed the expression profile of BPI protein in some tissues from mice in physiological condition or by LPS stimulation. Our results showed that BPI protein expressed physiologically in some tissues and cells in mice, and its expression level could be increased or induced by LPS stimulation.

Key words: lipopolysaccharide, bactericidal/permeability-increasing, anti-muBPI polyclonal anti-serum, immunohistochemistry