Antigen- and receptor-driven regulatory mechanisms. X. The induction and suppression of hapten-specific granulomas.

We have investigated the induction and suppression of granuloma formation elicited by the azobenzenearsonate (ABA) determinant in A/J Mice. ABA-derived syngeneic spleen cells (ABA-SC) administered subcutaneously induced hapten-specific delayed hypersensitivity (DTH), detected by footpad swelling, upon challenge with ABA-bovine serum albumin (BSA) coupled to polyacrylamide beads (PAB). The reactions elicited by ABA-BSA-PAB reached maximal intensity at 24 hours but were relatively persistent and were still marked at 96 hours. Histopathologic examination of footpad responses at 24 and 48 hours after challenge revealed compact collections around beads of mononuclear cells and granulocytes, which were characteristic of DTH reactions. Discrete epithelioid granulomas became apparent by 72 or 96 hours. Unprimed mice or mice primed with ABA-SC and challenged with uncoupled beads did not develop either substantial leukocytic infiltrates or granulomas. Persistent delayed responses were only apparent if the mice were challenged with the homologous hapten-coupled bead, indicating the fine specificity of the reaction. Immune cells were shown to be capable of transferring DTH and granulomatous responsiveness to ABA; the cells were sensitive to anti-Thy 1.2 antiserum and complement, which indicates that the response was thymic-dependent. The intravenous injection of ABA-SC, which is known to induce suppressor cells, prevented the development of DTH or granulomatous responsiveness followinggg subcutaneous immunization with ABA-SC. In addition, the transfer of suspensions containing suppressor T cells into syngeneic mice primed with ABA-SC prevented the development of DTH reactions and granuloma formation followin challenge with ABA-BSA-PAB. Furthermore, only hapten-specific suppressor T cells limited persistent delayed hypersensitivity responses. Having successfully developed granulomas in the footpad, the authors induced and suppressed granulomatous lesions in the gastrointestinal tract in a similar fashion. These experiments establish a model in inbred mice for the study of granulomatous diseases, including those of the gastrointestinal tract.