Intralesional plasma cells and serological responses in human cutaneous leishmaniasis

Intralesional plasma cells and serological responses were investigated in 20 Brazilian cases of cutaneous leishmaniasis. Plasma cell numbers varied from less than 10% to more than 50% of cells in inflammatory infiltrates, in general with greater numbers of such cells present in lesions of longer duration. Direct fluorescence examination with anti-IgG, -IgA and -IgM sera of trypsin-treated sections of formalin-fixed biopsy tissue revealed that most intralesional plasma cells contained IgG. Russell bodies were detected in eight cases, in seven of which these bodies fluoresced only with anti-IgM serum. There was no correlation between serum levels of total IgG, IgA and IgM (detected by radial immunodiffusion) or antileishmanial antibodies (detected by class-specific indirect immunofluorescence and by direct agglutination with and without 2-mercaptoethanol) and numbers of intralesional plasma cells of the same globulin class. No striking or consistent alterations in complement components were noted in the serum of these patients.