Antigen-specific mast cell degranulation in contact sensitivity to picryl chloride. An early event.

Mast cells from the peritoneum of mice painted with the contact sensitizing agent picryl chloride degranulate when exposed to antigen (TNP) in vitro. Degranulation was consistently demonstrated 4 days after painting which associated with the ability of mice to produce contact sensitivity reactions as measured by ear swelling and radiometric assays. Serum reagin or reagin-producing cells could not be detected until 6 days after painting but TNP-phage neutralizing activity was detected after 2 days. Mast cell degranulation could be elicited by TNP or DNP derivatives indicating the involvement of antibody.