Serum markers of rheumatoid arthritis in visceral leishmaniasis: Rheumatoid factor and anti-cyclic citrullinated peptide antibody

Rheumatoid factor (RF) has been described in visceral leishmaniasis (VL). However, there is no report of RF-isotype or other rheumatoid arthritis (RA) autoantibody in VL. This work investigated RF and anti-cyclic citrullinated peptide antibody (CCP-Ab) in sera from 35 inhabitants from a VL area: 15 from healthy persons (HIEA); 10 from VL patients (VL), and 10 from subjects cured of VL (CVL). The controls were represented by sera from 15 healthy individuals (HI) and from 10 RA patients from a VL free area. IgM-RF was investigated by immunoturbidimetry, while IgA-RF and CCP-Ab by enzyme-linked immunosorbent assay (ELISA). Increased RF-IgM production was found in 9 out of 10 sera from both VL and RA groups (median level 100 and 182 IU/ml respectively); in three out of CVL-sera (level 94 IU), and in only one HIEA-serum (level 58 IU). IgA-RF was only detected in RA-sera (5/10, 50%), while CCP-Ab was found in three VL and in four RA sera (median level 36.5 U and 161.5 U respectively). A strong correlation was observed between RF-IgM and VL in endemic area (P < 0.0001). We concluded that an increased IgM-RF production associated with sporadic and moderate CCP-Ab synthesis is an autoimmune characteristic of VL.