Surface IgE and phagocytic activity of eosinophils from patients with American cutaneous leishmaniasis: relation to...

Eosinophils were isolated from the blood of American cutaneous leishmaniasis (ACL) patients and healthy controls from the same endemic rural area (ERA) or from a non-endemic urban area (UA). For the purification of eosinophils a Percoll discontinuous gradient method was used. We obtained a good cell viability (between 90 to 95%) and the more pure layers, which were the densest, ranged from 85 to 95% eosinophils. A high proportion of the ACL patients and individuals from the ERA, had eosinophils in the low density layers (< 1.090 g/ml) and particularly at 1.070 g/ml. Using the immunoperoxidase (IP) staining and monoclonal antihuman IgE, surface IgE could be detected on eosinophils of different densities, and the hypodense fraction was the more positive. The phagocytic capacity for Leishmania promastigotes of eosinophils was also assessed. Eosinophils from the ERA group demonstrated the highest percentage of phagocytosis followed by the ACL patients. The UA group showed the lowest percentage, and the normodense fractions the lower phagocytic capacity. We found therefore that the hypodense layers had the highest percentage of detectable surface IgE and also the highest phagocytic capacity. We suggest that the surface IgE of activated eosinophils can contribute to their phagocytic function.