Antibodies reactive with liposomal phospholipids are produced during experimental Trypanosoma rhodesiense infections in rabbits.

Antibodies against phospholipids appeared spontaneously during the course of experimental Trypanosoma rhodesiense infections in rabbits. These antibodies were observed in rabbits infected either with a lethal strain or with a strain newly discovered to give a spontaneous self-cure. Serum antibodies reacting with liposomes containing dimyristoyl phosphatidylcholine (DMPC), phosphatidylinositol (Pl), phosphatidylinositol phosphate (PlP), or cardiolipin were detected at 3 to 4 wk by complement-mediated release of trapped marker from liposomes. Antibodies were also detected against a trypanosomal lipid fraction (TrF2) that contained Pl as a major constituent. The antibody activities against DMPC, Pl, or TrF2 all reacted (or cross-reacted) with DMPC, and were removed from the serum by adsorbing with liposomes containing DMPC as the only phospholipid. Phosphocholine inhibited the antibodies reactive with liposomes containing either DMPC or DMPC and Pl as phospholipids. Antibodies against PlP, however, reacted only with liposomes containing PlP and were not removed by adsorbing with liposomes lacking PlP. We conclude that anti-phospholipid antibodies appear during the course of trypanosomal infections that either undergo apparent self-cure or are lethal, and at least two anti-phospholipid antibody specificities can be detected.