Abstract: Objective To explore the ability of combination of Helicobacter pylori (Hp) and its' L-form with Surfactant protein D(SP-D), and the function of SP-D in Hp infection and immunity. Methods SP-D were extracted from the lung of rats by Tris-HCl-EDTA and maltose-agarose affinity column. The combination of Hp and SP-D were detected by slide and tube agglutination tests, and the agglutination inhibition with SP-D immune sera was carried out. The L-form of Hp was induced by Ceftriaxon sodrum and identified by PCR and sequencing of the 16SrDNA fragment.The combination of SP-D and the L-form was detected by the slide agglutination test. Results Agglutination of Hp NCTC11637 and SP-D could be observed on slide, while which of NCTC11639, SS1 and the L-form couldn't. Agglutination could be detected 45 minutes after reaction and could be inhibited by SP-D immune sera. Conclusions The ability of combination with SP-D could be different between strains of Hp.The combination could be weakened or vanished when Hp lost the cell wall.

Key words: Helicobacter pylori, cell wall deficient, Surfactant protein D