Measurement of Adhesion Force between a Human Neutrophil and a Candida albicans Hyphae Using a Micromanipulation Technique

Yeast infection (candidiasis) is a common and persistent threat to human health. Normally harmless, the fungus Candida albicans is present in 40-80% of normal human beings, but in immune-compromised individuals, it can proliferate and cause a variety of health problems including pneumonia, septicemia, or endo[[Unsupported Character - Codename ­]]carditis. The fundamental mechanism towards the control of candidiasis and other fungal infections involves understanding how human neutrophils interact with β-Glucan, a polysaccharide present in fungal cell walls, at the single cellu[[Unsupported Character - Codename ­]]lar level. We hypothesize that the complement receptor 3 (CR3), a member of the integrin family, can recog[[Unsupported Character - Codename ­]]nize the β-Glucan on the C. albicans hyphae, initiating neutrophil adhesion and caus[[Unsupported Character - Codename ­]]ing a respiratory burst. We test this hypothesis using a two-pipette micromanipulation technique to measure the adhesion force between a single neutrophil and a C. albicans hyphae. A micromanipulator attached to a suction pipette is used to trap a single C. albicans hyphae that is attached by a single neutrophil to a second, flexible pipette. The micromanipulator slowly pulls up on the hyphae, exerting an increasing force and causing the flexible pipette to bend until the hyphae detaches from the neutrophil. By measuring the deflection of the flexible pipette at the instant the hyphae detaches, Hooke's law can be used to calculate the adhesion force between the hyphae and the neutrophil. By measuring the average adhesion force of neutrophils from knock-out mice missing CR3 and compare with that from the wild type animals expressing CR3, we can determine the mechanical role the receptor plays in neutrophil adhesion.