In vitro effect of 5-hydroxytryptamine on concanavalin-A agglutinability and multiplication of Entamoeba histolytica.

Six isolates of E. histolytica isolated and maintained by serial passage in modified Boeck and Drbohlav's medium were used in this study. When five of the isolates were grown in the above medium with 5-hydroxytryptamine (5-HT) added to the overlay, the agglutinability of the amoebae by concanavalin- A (con-A) was significantly increased compared to corresponding control cultures. Four isolates of E. histolytica grown with 5-HT had 1.5 to 2 times higher counts than the control cultures. Similarly the con-A agglutinability and counts of cultures of NIH-200 (an axenic strain of E.histolytica) were enhanced when grown in association with 5-HT.