01504nas a2200217   4500000000100000008004100001260000900042653002900051653003100080653001100111653002700122653001200149653002300161653002200184100001300206245005800219300001100277490000700288520097700295022001401272       1988                            d  c198810aFalse Positive Reactions10aHost-Parasite Interactions10aHumans10aImmunologic Techniques10aleprosy10aParasitic Diseases10aRheumatoid Factor1 aHarboe M00aRheumatoid factors in leprosy and parasitic diseases.  a309-130 v753 a<p>Rheumatoid factors (RFs) occur with higher frequency and in higher titres in multibacillary forms of leprosy and several parasitic diseases than in healthy controls. The selection of controls is essential in studies of this kind. They should be individuals without signs of the disease under study living under similar socioeconomic conditions as the patients in the endemic country. In three studies where this matter was considered, RFs in lepromatous leprosy and Chagas' disease reacted more strongly with rabbit than human IgG, a feature generally considered to be quite restricted to rheumatoid arthritis. RFs interfere in various test systems, particularly in inducing false positive reactions for specific IgM antibodies in parasitic and other infectious diseases. Model experiments in rats, in vitro culture studies, and observations in humans indicate that RFs may have a protective role in trypanosome infections, malaria and schistosomiasis respectively.</p>  a0301-3847