title: The role of immunoglobulin and complement in enhancing the respiratory burst of neutrophils against Trichomonas vaginalis.
abstract: Human neutrophils, alone, did not kill Trichomonas vaginalis. More than 90% of T. vaginalis (10(5)/ml) survived in the presence of 10% normal human serum (NHS) while 90% of these organisms were killed in the presence of a combination of neutrophils (10(6)/ml) and 10% NHS. Mechanisms responsible for this serum-mediated neutrophil killing of T. vaginalis were demonstrated through a process of lucigenin-amplified neutrophil chemiluminescence. As evidenced by indirect immunofluorescence, NHS showed specific immunoglobulin G (IgG) titre of 1:8 for T. vaginalis. Purified IgG, at 1.6 mg/ml, showed no direct opsonizing or lytic effect on this organism. Formalin-fixed trichomonads opsonized by C2 deficient human serum promote 4 times more neutrophil chemiluminescence than those opsonized by Factor B deficient human serum. With the addition of purified IgG (5 mg/ml) neutrophil chemiluminescence was increased by 4 times and further improved trichomonal killing by neutrophils (from 5 +/- 4% to 78 +/- 16%) via activation of the classical complement pathway, but did not alter that due to activation of the alternative complement pathway. These studies indicate that both an IgG-enhanced classical complement pathway activation and an antibody-independent alternative complement pathway activation provide opsonin (C3) for T. vaginalis to facilitate the neutrophil killing mechanism.
authors.affiliation: Department of Parasitology and Tropical Medicine, National Defense Medical Center, Taipei, Taiwan, Republic of China.
authors.forename: M F
authors.initials: MF
authors.lastname: Shaio
authors.forename: F Y
authors.initials: FY
authors.lastname: Chang
authors.forename: S C
authors.initials: SC
authors.lastname: Hou
authors.forename: C S
authors.initials: CS
authors.lastname: Lee
authors.forename: P R
authors.initials: PR
authors.lastname: Lin
mesh_terms: D000328:Adult; D000818:Animals; D003167:Complement Activation / Q000276:immunology; D015941:Complement Hemolytic Activity Assay; D003165:Complement System Proteins / Q000276:immunology*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D008297:Male; D009504:Neutrophils / Q000276:immunology*; D009895:Opsonin Proteins; D014246:Trichomonas vaginalis / Q000254:growth & development*
chemical_list: D007074:Immunoglobulin G; D009895:Opsonin Proteins; D003165:Complement System Proteins