Sera from lupus patients inhibit growth of P-Falciparum in culture

A large number of malaria immune persons from Eastern India were found to p ossess antibodies to the ribosomal phosphoprotein P0 (PfP0) of the human ma larial parasite Plasmodium falciparum. The characterization of PfP0 has bee n reported recently, and it has been shown that antibodies against PfP0 inh ibit P. falciparum in vitro. About 10-15% of the patients suffering from th e autoimmune disorder Systemic Lupus Erythematosus (SLE) possess autoantibo dies to the human ribosomal P proteins. In order to test the cross-reactivi ty of the human and Plasmodium falciparum P0 proteins and to compare the SL E patients' and malaria immune persons' response, sera from 41 Indian SLE p atients were tested against the P.falciparum PfP0 by Western blot analysis. Four of these samples (9.75%) were found to be cross-reactive to the carbo xy-terminal domain of PfP0, but not to the amino-terminal domain of PfP0. T he PfP0 reactive SLE sera inhibited the growth of Plasmodium falciparum in vitro. IgG purified from one such cross-reactive serum sample inhibited the growth of P. falciparum. Depletion of anti-P0 antibodies from this IgG pre paration resulted in the removal of growth inhibition. Sera samples were co llected from one of the PfP0 positive SLE patient from Mumbai, India, at di fferent stages of the disease progression, and screened for the presence of anti-PfP0 antibodies. This patient's serum inhibited the parasite growth i n vitro only during the phase in which anti-PfP0 antibodies were detected.