Abstract
Purpose: :
The intracameral injection of antigen recruits circulating F4/80+ cells to the anterior chamber that recirculate through the anterior chamber (AC) to the thymus and to the spleen where CD8+ regulatory T cells are induced. Because these regulatory T cells specifically suppress active cell-mediated immunity, it is likely that there is a quantifiable increase in the number of these regulatory T cells during immunization. To test this hypothesis, we quantified the number of splenic, antigen-specific CD8+ regulatory T cells induced by the injection of antigen into the AC of naïve and immunized mice.
Methods: :
Mice were immunized one week after receiving an intracameral injection of TNP-BSA or ovalbumin (OVA) or were not immunized. The suppression of the expression of contact sensitivity to the immunizing antigen in immunized mice by splenic regulatory T cells was quantified by the injection of graded numbers of AC-induced total splenic or CD8+ T cells concurrent with the challenge antigen into the footpads of immunized mice. The number of splenic regulatory cells required to effect a 50% reduction in the swelling of the challenge site was taken as a metric to quantify the regulatory T cells.
Results: :
The antigen-specific suppression of the expression of contact sensitivity by AC-induced regulatory spleen cells was proportional to the number of cells injected into a footpad challenged by antigen. The intracameral injection of antigen induces only antigen-specific CD8+ regulatory T cells that are specifically increased at least 3-4 fold when the mice are immunized. Splenic CD8+ regulatory spleen cells induced by the intracameral injection of antigen are stable at the challenge site no more than 3 days after injection.
Conclusions: :
The intracameral injection of antigen quantitatively expands splenic CD8+ regulatory T cells induced by immunization. Quantifying these regulatory T cells provides an improved basis for quantifying anterior chamber-associated immune deviation (ACAID).
Keywords: ACAID • immunomodulation/immunoregulation • immune tolerance/privilege