In order to clarify the factors responsible for the cellular infiltrate characteristic of
anterior uveitis, the authors have induced
inflammation in rabbits by the
intravitreal injection of 100 ng of Escherichia coli or
Salmonella endotoxin (ET). A 2% concentration of aqueous humor 18 to 24 hr after ET consistently induced monocyte migration as measured in modified Boyden chambers. Activity was significantly greater in these samples than in aqueous after saline injection or 3 hr after
endotoxin injection (prior to cellular infiltrate). Using either
sephadex G-75 molecular sieve chromatography or a cibacron blue column, the vast majority of migratory activity co-eluted with
albumin.
Serum albumin, however, at a comparable concentration did not induce migration. Activity was largely heat- and
acid-stable and was maximal in the presence of a concentration gradient, indicating that it was chemotactic rather than chemokinetic. A second peak of activity eluted from the G-75 column just prior to a marker with molecular weight of 427 and was also present in eluates from normal aqueous humor.
Chloroform:
methanol extraction, radioimmunoassay, and high performance liquid chromatography indicated that a small portion of the chemotactic activity could be ascribed to
lipid including
leukotriene B4. In contrast to the prominence of
complement (C5a) derived chemotactic activity resulting from intravenous ET, C5a was not a major contributor to aqueous chemotactic activity subsequent to local ET. These observations demonstrate that leukocyte migration factors in aqueous humor can be characterized and compared. This approach can be used to test the hypothesis that subsets of anterior uveal
inflammation might be distinguished on the basis of associated
chemotactic factors.