Sera from Lupus Patients Inhibit Growth of P. Falciparum in Culture

Abstract

A large number of mal ariaimmun e persons from Eastern India were found to possess antibodies to the ribosomal phosphoprotein PO (PfPO) of the human malarial parasite Plasmodium falciparum. The characterization of PfPO has been reported recently, and it has been shown that antibodies against PfPO inhibit P. falciparum in vitro. About 0-15% of th e patients suffering from the autoimmune disorder Systemic Lupus Erythematosus (SLE) possess autoantibodies to the human ribosomal P proteins. Inorder to test the cross-reacti vity of the human and Plasmodium falciparwn PO prote in sand to compare the SLE patients’ and malaria immune persons’ response, serafrom 41 Indian SLE patients were tested against the P. falciparum PfPO by Western blot analysis. Four of these samples (9.75%) were found to be cross-reactive to the carboxy-termin al domain of PfPO , but not to the a mino-terminal do main of PfPO . The PfPO reactive SLE ser a inhibited the growth of Plasmodium falciparum in vitro. IgG purified from one such cross-reacti veserum sample inhibited the growth of P. falciparum. Depletion of anti-PO antibodies from this JgG preparati on resulted in the remova l of growth inhibition. Ser a samples werecollected from one of the PfPO positive SLE patient from Mumbai, fndia, at different stages of the di sease progression , and screened for the presence of anti-PfPO antibodies. This patient’s serum inhibited the parasite growth invitro only during the phase in which anti-PfPO antibodies were detected.