[Plasmodium lactate dehydrogenase activity assay and its preliminary application in therapeutic efficacy monitoring of drugs].

OBJECTIVE: To evaluate the activity of Plasmodium lactate dehydrogenase (pLDH) in relation to the degree of parasitemia and laboratory culture time of the parasite, and explore the feasibility of using the activity assessment in monitoring the effect of drug therapies. METHOD: Using enzymatic colorimetric method, pLDH activities were assayed in the blood samples of different degrees of parasitemia and of varied in vitro culture time. Blood samples from a patient with P.falciparum and P.vivax infection were also collected before and after chemotherapy for pLDH activity assay. RESULTS: pLDH activity increased as parasitemia escalated and the culture time prolonged. The strongest activity was observed between 36 and 48 h of incubation when the trophozoites and schizonts were predominant. pLDH activities were reduced in the blood sample of the patient collected after chemotherapy, completely undetectable after 5 d. CONCLUSION: pLDH activity assay would potentially be of value in detecting specific Plasmodium clones and monitoring efficacy of drug therapy.