The data presented here indicate that the C5 reaction step may proceed via the specific attachment of C5 to EAC1,4,2,3 and the formation of a hemolytically active C5 intermediate complex. During this process only a minor proportion (less than 4%) of C5 offered to EAC1,4,2,3 becomes bound, although the remaining C5 also participates in the reaction as evidenced by its inactivation in the fluid p...

Hydrosalpinx is a pathological hallmark of tubal infertility associated with chlamydial infection. However, the mechanisms of hydrosalpinx remain unknown. Here, we report that complement factor 5 (C5) contributes significantly to chlamydial induction of hydrosalpinx. Mice lacking C5 (C5(-/-)) failed to develop any hydrosalpinx, while ∼42% of the corresponding wild-type mice (C5(+/+)) did so fol...

Sexual dimorphism of mouse complement component 5 (C5) was detected by isoelectric focusing of desialated ethylenediamine tetraacetic acid (EDTA)-plasma on agarose gel, followed by immunofixation with anti-mouse C5. Male plasma displayed two C5 bands, basic and acidic, while female plasma had only a basic C5 band. In all mouse strains tested except C5-deficient strains, the identical patterns o...

Eculizumab inhibits the terminal, lytic pathway of complement by blocking the activation of the complement protein C5 and shows remarkable clinical benefits in certain complement-mediated diseases. However, several reports suggest that activation of C5 is not always completely suppressed in patients even under excess of eculizumab over C5, indicating that residual C5 activity may derogate the d...

A unique experimental model is described, where natural immunologic tolerance to a well-defined soluble native antigen (murine C5) is examined in congenic strains of mice that differ only by the presence or the absence of C5. A highly sensitive hemolytic assay was developed to detect nanogram amounts of C5 as well as an assay of anti-C5 inhibition of C5 hemolytic activity. The latter was more s...

Experimental conditions required for the expression of maximum C5 activation upon limited trypsin hydrolysis were determined to be 0.008 mol of trypsin/mol C5 in a reaction mixture containing 1 mg C5/ml veronal-buffered saline incubated at 37 degrees C for 30 min. Employing these optimal incubation conditions, the primary or preferred site of trypsin hydrolysis of the C5 alpha-chain resulted in...

Leptospirosis is considered one of the most important zoonosis worldwide. The activation of the Complement System is important to control dissemination of several pathogens in the host. Only a few studies have employed murine models to investigate leptospiral infection and our aim in this work was to investigate the role of murine C5 during in vivo infection, comparing wild type C57BL/6 (B6 C5+...

Complement C5-deficient (C5(-/-)) macrophages derived from B.10 congenic mice were found to be defective in killing intracellular Mycobacterium tuberculosis (MTB). They were bacteriostatic after activation with IFN-gamma alone but bactericidal in the combined presence of IFN-gamma and C5-derived C5a anaphylatoxin that was deficient among these macrophages. Reduced killing correlated with a decr...