Abstract
Antitoxins are frequently equine IgA (T) immunoglobulins which fix complement poorly and form soluble complexes in antitoxin excess. Such antisera produce unusual vascular clearance of toxin-antitoxin complexes. Clearance in rats of staphylococcal enterotoxin-equine antitoxin complexes has been examined throughout the range of antigen to antibody ratios by varying the amount of passively administered antitoxin. In toxin excess, clearance of the complexes was slow and independent of antisera concentration until sufficient antitoxin was present to bind 80% of the toxin. At equivalence, clearance was rapid; cellular localization revealed the majority of complexes in reticuloendothelial system (RES) cells. In antibody excess, high molecular weight non-precipitating complexes were formed yet the clearance rate slowed, decreasing further with additional excess antisera. Clearance rate correlated with the amount of precipitate formed in vitro at equivalent antitoxin to toxin ratios. These observations suggest that rapid removal of toxin and its catabolism by RE cells cannot be an important mechanism of detoxification by antibody in vivo. In fact, equine antitoxin functioned as an opsonin only when it reacted with toxin to produce aggregates whose solubility in plasma appeared to be the critical determinant to recognition by the RES.
- Received July 6, 1971.
- Copyright, 1972, by The Williams & Wilkins Company
- Copyright © 1972 by The American Association of Immunologists, Inc.
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