Serum antibodies blocked by glycan antigens in canine visceral leishmaniasis serology are mostly IgA immune complexes

Author(s)

Aparecida de Carvalho, Camila ^{[1, 2]} ; Mitsuyoshi Hiramoto, Roberto ^[3] ; Regina Meireles, Luciana ^[1] ; Franco de Andrade Junior, Heitor ^{[1, 2]}

Affiliation

^[1] Univ Sao Paulo, Lab Protozool, Fac Med, Inst Med Trop, Av Doutor Eneas Carvalho Aguiar 470, BR-05403000 Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Dept Patol, Fac Med, Av Doutor Eneas Carvalho Aguiar 470, BR-05403000 Sao Paulo, SP - Brazil

^[3] Adolfo Lutz Inst, Lab Parasitoses Sistem, Av Dr Arnaldo 355, BR-01246000 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Parasitology; v. 148, n. 12, p. 1509-1515, OCT 2021.
• Web of Science Citations: 0

Abstract

Immune complexes (ICs) are found in canine visceral leishmaniasis (CVL) and interfere with the serum detection of antibodies. Dissociation of these monovalent complexes by dissociative enzyme-linked immunosorbent assay (ELISA) removes false-negative results and allows some characterization of antibodies and antigens. We studied the serology of dogs with suspected CVL in an endemic area, testing two Leishmania (Leishmania) {[}L. (L.)] <full form> infantum antigens. We analysed the presence of immunoglobulin G (IgG), immunoglobulin A (IgA) and immunoglobulin M (IgM) antibodies specific to promastigote soluble extract (PSE) and low-molecular weight glycans (glycan-bovine serum albumin (BSA) complex - GBC) by conventional and dissociative ELISA. Our results showed a significant fraction of IgA ICs (46.5% for PSE and 47.6% for GBC), followed by IgG ICs (10% for PSE and 23.5% for GBC). IgM ICs were more frequent for PSE (22.7%). Hypergammaglobulinaemia in CVL would be related to the presence of IgA and IgG ICs, resulting in deficient elimination of these antibodies. Our data confirmed the presence of ICs that can generate false-negative results in conventional serology. The production of IgA antibodies and the high frequency of blockade by glycan antigens suggest the active participation of this immunoglobulin and its ICs in the immunopathology of CVL, indicating a new path for further research. (AU)

• FAPESP's process: 17/14675-0 - Humoral immune response to haptens of L. (L.) infantum chagasi by detection of specific and natural antibodies in experimental and natural visceral leishmaniasis
• Grantee: Camila Aparecida de Carvalho
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 17/26558-9 - Haptens in visceral leishmaniasis. Development of solid phase assays for diagnosis and its immunology in experimental models.
• Grantee: Heitor Franco de Andrade Junior
• Support Opportunities: Regular Research Grants