The role of mast cells in endotoxin-induced uveitis.
OBJECTIVE
To investigate the role of mast cells in the induction of endotoxin-induced uveitis (EIU).


METHODS
We previously showed that the mean mast cell number in the anterior uvea was greatest for Lewis rats, lowest for Brown Norway (BN) rats, and intermediate for LBNF1 rats. In the current experiment, we assessed the time of onset and severity of EIU in these three rat strains. We then studied changes in mast cell numbers in the anterior uvea during the induction period of EIU.


RESULTS
Time of onset and severity of EIU were related to the number of mast cells in the anterior uvea. EIU occurred earliest in the Lewis rats, and the maximum mean grade of ocular inflammation on a scale of 0 (no inflammation) to 4 (severe inflammation) +/- standard error of the mean was 3.87 +/- 0.13 for Lewis rats, 1.06 +/- 0.06 for BN rats, and 1.19 +/- 0.12 for LBNF1 rats. The difference between the mean grade of inflammation in the Lewis rats and the other two strains was highly statistically significant (P < .001). In the Lewis rats, mast cell numbers +/- SEM decreased from 68.9 +/- 10.8 at baseline to 49.6 +/- 5.9 4 hr after lipopolysaccharide (LPS) injection and to 27.6 +/- 8.4 8 hr after LPS injection, suggesting that mast cell degranulation occurs before the development of EIU.


CONCLUSIONS
Mast cells in the anterior uvea appear to potentiate endotoxin-induced ocular inflammation.
Li
Q
Q
Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892.
Whitcup
S M
SM
Fujino
Y
Y
Nussenblatt
R B
RB
Chan
C C
CC
D000818:Animals; D001427:Bacterial Toxins; D002452:Cell Count; D002924:Ciliary Body / Q000473:pathology; D004731:Endotoxins; D005260:Female; D007498:Iris / Q000473:pathology; D008407:Mast Cells / Q000502:physiology*; D051381:Rats; D011914:Rats, Inbred BN; D011917:Rats, Inbred Lew; D014606:Uveitis, Anterior / Q000209:etiology*
D001427:Bacterial Toxins; D004731:Endotoxins; C027952:salmonella toxin