For synchronization, mostly ring stage parasites (10 to 12 h post-invasion) wen~ used. The parasite culture was centrifuged at 200g for 5min and the supernatant was discarded. To the pellet, 4 ml of 5% sorbitol was added, mixed gently and incubated for 15min at 37°C. The mix was shaken 2 or 3 times and centrifuged at 200g followed by washing 3 times in complete medium (list I). The culture was then maintained at 5% hematocrit in a 37°C incubator

All antisera were obtained from the reagent bank at National Institute of Immunology, New Delhi.