Evaluation and characterization of partially purified skin test antigens prepared from Leishmania panamensis promastigotes.

Abstract

The present study was designed to evaluate skin test preparations prepared from Leishmania panamensis promastigotes in 30 active cutaneous leishmaniasis patients. The crude antigen preparation (CA) used was 10, 000×g supernatant of the parasiteshomogenate. The soluble extract was further resolved into 4 preparations (FA-1 to-4) with the aid of a Sephacryl S-200 gel filtration. There was no significant difference in the positive ratio and the average induration size between CA (10 μg protein/test) and Montenegro's antigen (MA;5×106 parasites/test). The reactivity of the delayed-type hypersensitivity to 10 μg dose of CA was shown with much the same intensity in the 25 μg dose of CA. In FAs (10 μg protein dose, except for 7.5 μg. in FA-4), the positive ratio was as follows : 90.0% in FA-1, 77.8% in FA-2, 75.0% in FA-3 and 37.5% in FA-4. The positive ratio and the intensity of skin test response in FA-4 were remarkably low in comparison with those in CA or MA. Significant difference was found in the intensity of response between FA-3 and CA or MA. Based on these results, therefore, we concluded that 10 pg protein dose of CA of L. panamensis and same dose of the fractionated preparations, FA-1 and-2, were very suitable for the diagnosis of cutaneous leishmaniasis in endemic areas of the New World. Furthermore, it was estimated that at least some or all of the 5 proteins, approximately 66, 55, 45, 28, and 26 kD, were related to a specific delayed-type hypersensitivity in cutaneous leishmaniasis of the New World.