A comparison of mycelial filtrate - and yeast lysate - paracoccidioidin in patients with paracoccidioidomycosis.

A cytoplasmic antigen was obtained from P. brasiliensis yeast cells by water lysis and sonication, with the aim of detecting delayed hypersensitivity to the fungus. This antigen was studied in patients with paracoccidioidomycosis (active and inactive), tuberculosis and histoplasmosis as well as in normal individuals, and it was compared with a mycelial filtrate antigen employed in the past for the same purpose. The yeast paracoccidioidin proved superior to the mycelial preparation (62.0 vs 24.1%) in patients with active paracoccidioidomycosis; however, in inactive cases, both preparations gave similar results. The size of the reactions was also comparable for both products. In normal subjects and in patients with tuberculosis, skin reactivity was low (not over 10%) and within the expected range of the area. In contrast, patients with histoplasmosis proved highly reactive to both antigens. These results indicate that the newer paracoccidioidin has advantages over the mycelial product as it detects a higher proportion of reactors and as such, may be helpful in studies aimed at defining areas of endemicity in countries where paracoccidioidomycosis is present.