Antischistosome antibodies change NTPDase 1 activity from macrophages

NTPDases are enzymes that hydrolyse diphosphate and triphosphate nucleosides, regulating purinergic signalling in many organisms. The Schistosoma mansoni NTPDases, SmATPDases 1 and 2, are antigenic proteins and display a significant homology with the isoforms found in mammalian cells. In this work, we investigated whether anti-SmATPDase antibodies from S. mansoni-infected mice sera show cross-reactivity with the NTPDase 1 isoform from macrophages and how this event affects the cell proliferation. By Western blot, anti-SmATPDase antibodies present in serum from infected mice recognized 2 bands with approximately 53 and 58 kDa, corresponding to NTPDase 1. Additionally, the enzyme was identified in macrophages by immunofluorescence and the anti-SmATPDase antibodies were able to reduce activity enzyme (22%). Macrophages incubated with commercial polyclonal antibodies reactive with NTPDase 1 (anti-CD39) showed a reduction of 40% of the enzyme activity. In proliferation assays, macrophage proliferation was inhibited 11% and 90% by pooled sera from infected animals and anti-CD39, respectively. The results suggest that inhibition of NTPDase 1 in macrophages by antibodies produced against the isoforms of the S. mansoni ATPDases could be a mechanism of regulation in the immune response during experimental schistosomiasis.