Evaluation of four commercial antibodies

Flow cytometer-derived fluorescence measurements were used to evaluate lot- to-lot variability, cross-reactivity, and avidity of four antibodies. Varia bility within kit 3 and 4 antibody lots was great, whereas kits 1 and 2 sta ined parasites consistently. Kit 3 and 4 antibodies cross-reacted with non- parvum Cryptosporidium; kit 1 and 4 antibodies cross-reacted with Giardia m uris Kit 1 (primary only) 2, and 3 anti-Cryptosporidium antibodies formed l ow-avidity complexes, unlike those in kits 1 (secondary) and 4 and all Giar dia antibodies. Additionally, the authors quantified the ability of antibod ies to bind stressed and unstressed parasites following methodological proc essing. The studies identified significant differences in antibody characte ristics and performance.