gms | German Medical Science

Background: The diffuse nasal polyposis is in 70% of cases predominantly by inflammation caused by eosinophils. In the pass neutrophils were detected in the tissue of nasal polyps but their clinical relevance is unclear. The neutrophil activated peptid 2 (NAP-2) was measured in polyps and is generated by proteases from ß-thromboglobulin (ß-TG) precursors and not over gene expression.

Material and Methods: Human nasal polyps were homogenized and protein extraction was performed by treating with acid ethanolic solution. After centrifugation the supernatant was concentrated and diafiltrated. The ß-TG proteins (connective tissue activating peptide III (CTAP-III), NAP-2 and platelet basic protein (PBP)) were separated by using an immunoaffinity column. The eluated fractions were investigated concerning protein level and chemotactic activity by using the several methods: Western-blotting, ß-TG ELISA, Boyden-chamber assay. The ratio of chemokines on western blots was detected by infrared fluorescence (LI-COR).

Results: Western blotting has shown three protein bands which were indicated to CTAP-III, NAP-2 and PBP. The total ß-TG was determined by ELISA (about 1300ng/ml polyps). Additionally, we determined the ratio of CTAP-III to NAP-2 by using infrared fluorescence. With the ratio of 3:1 and the result of the ß-TG-ELISA the concentration of NAP-2 was estimated to 17ng / 1g nasal polyp wet tissue weight. The biological activity is due from NAP-2 because the precursor CTAP-III and PBS has not the potential to functionally activate neutrophils.

Conclusion: The isolation and characterisation of the biological active NAP-2 from human nasal polyps has been shown. Obviously the truncation caused by proteases plays an important role for the regulation of NAP-2.