Experimental allergic gingivitis: I. Local non‐reactivity of the rat gingiva following multiple antigenic challenges

One to eight injections of BSA or saline were given into the gingiva of sensitized or nonsensitized rats. The mucous membrane of untreated rats was found to be mildly inflamed. A single injection of BSA or saline caused moderate to severe gingivitis. The severity and incidence of gingivitis decreased with increasing number of injections of BSA or saline into the mucosa. This phenomenon of induced “local non‐reactivity” is similar to that observed in the parotid gland after multiple introductions of antigen.