Louis, MO, USA) in a volume of 100 μL RPMI 1640 (Nissui) without antibiotics for 5 hr. Amounts of CRAMP in the culture supernatant were determined by ELISA as described above. Results expressed as means and SD were compared using one-way analysis of variance. The differences between learn more each group were compared by multiple comparisons (Bonferroni t test). Differences were considered significant at P < 0.05. Cathelin-related antimicrobial peptide was examined for its antimicrobial activity against M. pneumoniae. As shown in Figure 1, CRAMP exerted antimicrobial

activity against M. pneumoniae M129 and FH strains in a dose dependent manner in the range of 10 to 20 μg/mL. At a concentration of 20 μg/mL the number of mycoplasmal colonies was reduced by 100 to 1000-fold as compared with the control. These results show that CRAMP possesses antimicrobial activity against M. pneumoniae. To determine whether M. pneumoniae infection induces CRAMP production, CRAMP concentrations in BALF of M. pneumoniae-infected mice were determined using a sandwich ELISA. As shown in Figure 2, CRAMP concentrations in BALF of M. pneumoniae-infected mice were 20–25 ng/mL, whereas the corresponding concentrations Selleck Ku0059436 for control uninfected mice were 0.7–1.1 ng/mL. To further confirm the presence of CRAMP in the supernatant of

the BALF, Western blotting was performed using a rabbit anti-CRAMP Ab. As shown in Figure 3, the 3.8 kDa band of the mature form of CRAMP and a 18 kDa band corresponding to the CRAMP immature form were detected. Synthetic CRAMP peptide was

Idoxuridine detected at 3.8 kDa in accordance with its molecular weight. The results showed that M. pneumoniae infection induces CRAMP in the BALF of M. pneumoniae-infected mice. It is, however, still unknown which cells are responsible for CRAMP production. Approximately 90% of the cells in the BALF were neutrophils, the rest being monocytic cells. CRAMP expression of the neutrophils in the BALF was also examined. As shown in Figure 4, expression of CRAMP was evident fairly widespread throughout the neutrophils, particularly in the area of the nuclear membranes. The neutrophils were confirmed to have polynuclear morphology by Hoechst 33342 staining. In contrast, CRAMP was not detected within neutrophils by normal serum. These results indicate that neutrophils are a primary source of CRAMP in M. pneumoniae-infected BALF. In the next experiments, we examined whether M. pneumoniae can induce the release of CRAMP from neutrophils. Neutrophils induced by thioglycolate were used in this experiment. Cells that had already been activated by thioglycolate released small amounts of CRAMP, approximately 1.7 ng/mL. Addition of M. pneumoniae induced CRAMP of approximately 20 ng/mL in the supernatant after 5 hr (Fig. 5). The viability of neutrophils after 5 hr incubation was approximately 95% as judged by the trypan blue exclusion test.