Cell-mediated immune response to dog pulp tissue altered by 6.5% paraformaldehyde via the root canal

Pulp tissue from three experimental dogs was tested for its antigenicity before and after incubation with 6.5% paraformaldehyde. Reactions to cell-mediated skin tests showed an increased response to pulp that had been incubated in paraformaldehyde, washed, and then injected, as compared with pulp or paraformaldehyde alone. In vitro, analysis of cell-mediated immune response (lymphocyte proliferation) showed a distinct increase when pulp tissue was incubated in paraformaldehyde and washed as compared with saline-treated pulp. The increase in radioactivity was statistically significant at P