Dermal granulomatous hypersensitivity in Q fever: comparative studies of the granulomatous potential of whole cells of Coxiella burnetii phase I and subfractions.

Dermal granulomatous reactivity to Q fever antigens in guinea pigs has been described as a model for vaccine reactions seen in previously sensitized humans. This model has now been applied to study the ability of subfractions of Coxiella burnetii to produce granulomas. Q fever organisms in phase I, trichloroacetic acid-soluble and -insoluble fractions, and the extract and residue of chloroform-methanol extraction were tested for their relative ability to elicit and immunize for dermal granulomatous reactions and specific lymphocyte proliferative responses in guinea pigs. The results suggest that a determinant(s) causing granulomas can be removed by chloroform-methanol extraction of phase I whole cells. The chloroform-methanol residue elicited strong delayed-type hypersensitivity without subsequent granuloma formation. The chloroform-methanol residue appears to possess a determinant(s) for lymphocyte stimulation equivalent to that of whole phase I organisms.