Aggravation of conjunctival early-phase reaction by Staphylococcus enterotoxin B via augmentation of IgE production.

PURPOSE: To investigate whether Staphylococcus enterotoxin B (SEB) affects the early-phase reaction (EPR) in experimental conjunctivitis.

METHODS

Nc/Nga mice were sensitized to ragweed (RW) or phosphate-buffered saline (PBS) in alum. The mice were subsequently treated three times a day with eye drops adulterated with SEB or vehicle on postimmunization days 29 to 31. On postimmunization day 32, the mice were administered eye drops adulterated with RW, and the EPR was evaluated. Ninety minutes after the RW challenge, the eyes were harvested for histological evaluation of degranulation of mast cells, and blood was drawn for subsequent measurement of serum antibody levels.

RESULTS

The total EPR score was significantly higher in the RW-sensitized mice than in the PBS-sensitized mice. Among the RW-sensitized mice, the SEB-treated mice had significantly higher EPR scores than did the vehicle-treated mice. Treatment with SEB significantly increased the degranulated mast cells in the eyes of the RW-sensitized mice. Serum levels of RW-specific IgG1 and IgG2a were significantly higher in the RW-sensitized mice than in the control mice. The total IgE level was significantly higher in the RW-sensitized, SEB-treated mice than in the other three groups of mice.

CONCLUSIONS

Topical SEB treatment upregulated systemic IgE production, which may augment conjunctival EPR.