Antibodies reacting with chloroquine in human sera

Presence of antibodies in human sera reacting with chloroquine (CQ) was dem onstrated from a malaria endemic belt. The study groups consisted of 53 hea lthy volunteers, receiving regular chloroquine prophylaxis [2 tablets of CQ (150 mg)/wk, single dose], 105 individuals with a history of frequent CQ i ntake for any febrile attack and 95 individuals from a non-endemic area who had neither a history of malaria nor of previous consumption of CQ. Sixty six per cent individuals taking regular prophylactic chloroquine and about ten per cent of those with a history of taking frequent chloroquine due to febrile illness in the malaria endemic area showed antibodies reacting to c hloroquine. However, antichloroquine antibodies were either insignificant o r nondetectable in serum samples collected from persons without any history of chloroquine intake. The results indicate a possible interaction of CQ i n vivo.