Anti-neutrophil cytoplasmic antibodies (ANCA) in malaria.

Various autoantibodies like anti-nuclear antibodies (ANA), anti-double stranded DNA (anti-dsDNA), anti-histone antibodies (AHA), anti-neutrophil cytoplasmic antibodies (ANCA), anti-myeloperoxidase (anti-MPO), anti-proteinase3 (anti-PR3) and anti-lactoferrin (anti-LF) antibodies were studied in 173 acute hospitalised patients suffering from malaria of which 160 patients had P. falciparum and remaining 13 had P. vivax infection. Standard methods like indirect immunofluorescence (IIF) microscopy along with Confocal microscopy and ELISA were used for identifying and quantifying the autoantibodies and IIF patterns on PMN and HL-60 cells were studied for ANCA classification. Also HEp-2 cells were used for ANA detection, while estimation of anti-dsDNA, AHA, anti-MPO, anti-PR3 and anti-LF were tested using ELISA. Sera from malaria patients showed prominent immunofluorescence staining patterns where 23.8% cases had ANA in P. falciparum group as compared to 15.4% in P. vivax group and ANCA was found to be present in 20% in P. falciparum and 15.4% in P. vivax group. An interesting observation was that, of the total ANCA positives, 59% had p-ANCA, 5.9% had c-ANCA and 44.1% of the cases showed the 'atypical' or X-ANCA pattern. When p-ANCA positivity was compared with c-ANCA positivity among these patients, a good statistical correlation was noted with OR = 16, chi 2 = 16.43, EF = 0.46 and p-value = 5.037E 0.5. ELISA showed 31.2% anti-MPO and 6.2% anti-PR3 in P. falciparum cases while the two ANCA positive cases in P. vivax had anti-MPO. Anti-LF was found to be present in 40.6% cases. Neither the P. falciparum nor P. vivax contained autoantibodies with specificities similar to the characteristic lupus autoantibodies such as double stranded DNA (dsDNA). ANCA positivity develops in some types of malarial infection also with the presence of various autoantibodies which is important from a clinical point of view and should be carefully evaluated in those geographic areas where malaria is endemic. It also alerts us to the fact, whether in cases of repeated malarial infections in susceptible individuals, vasculitic disorders, which through ANCA pathways develop, could lead to renal and other complications.