Lower levels of IgG1 in comparison with IgG2a are associated with protective immunity against Leishmania tropica infection in BALB/c mice

Background/Purpose: Leishmania (L.) tropica is the causative agent of different forms of human leishmaniasis. There is little information about the role of Leishmania-specific antibodies in the immune response against L. tropica infection. The aim of this study is to evaluate the role of Leishmania-specific antibodies and their immunoglobulin G (IgG) isotypes in L. tropica infection. Methods: L. tropica at two different doses (high dose, 10(6) parasites/mouse and low dose, 10(3) parasites/mouse) were used for infection of BALB/cmice. BALB/c mice infected with Leishmania major were used for comparison. Anti-Leishmania antibodies of the IgG1 and IgG2a isotypes were assayed by enzyme-linked immunosorbent assay. Results: Our data showed that (1) a higher parasite dose results in higher levels of antibody. (2) L. tropica infection results in a lower IgG1 antibody response, compared with L. major infection. (3) The IgG2a/IgG1 antibody response in L. tropica infection is higher than that in L. major infection. Conclusion: A higher IgG2a/IgG1 ratio is associated with protective immune response in L. tropica infection. These data can help to approach the complex profile of immunity against L. tropica infection. Copyright (C) 2015, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC.