Purpose: To examine conditions that determine the nature of the blood-borne, ACAID-inducing signal produced after intracameral injection of antigen.
Methods: Balb/c mice were splenectomized, rested, and injected in the anterior chamber with various antigens. Two days later the animals were bled, the plasma and white cells were isolated, and these fractions were transferred to naive mice (with spleens). Recipients were immunized subcutaneously within 2 to 7 days and delayed type hypersensitivity was assessed 10 to 14 days after immunization by challenge with the appropriate antigen.
Results: The antigens HSV-1, TNP-coupled cells, and P815 tumors cells induced a soluble ACAID-inducing signal found in the plasma portion of blood. The soluble protein antigens bovine serum albumin (BSA) and conalbumin induced a cell-associated signal. When T-cells were included with protein antigens, a soluble (not cellular) ACAID-inducing signal was induced.
Conclusions: Particulate antigens, such as HSV-1 and P815, that elicit intraocular T-cell responses or antigens that contain T-cells (e.g., TNP cells) induce a soluble, ACAID-inducing signal. Soluble antigens (e.g., BSA and conalbumin) induce a cell-associated ACAID signal. Additionally, T-cells are capable of modulating the type of ACAID signal produced. These results show that two methods of delivering the ACAID signal exist that are dependent on the nature of the antigen and the presence of T-cells. The authors conclude that the eye shows great versatility in regulating potentially damaging immune responses.