Effects of chelating agents on the initial interaction of phytohemagglutinin with lymphocytes and the subsequent stimulation of amino acid uptake

The chelating agents, ethylene glycol bis-(β-aminoethyl ether)-N,N′-tetraacetic acid (EGTA) and EDTA, had no effect on the initial interaction of phytohemagglutinin with lymphocytes at concentrations which have been shown previously to inhibit the development of the phytohemagglutinin response completely. However, they had a marked inhibitory effect on uptake of the amino acid analog, α-aminoisobutyric acid in both unstimulated and phytohemagglutinin-stimulated cells. The inhibition of amino acid uptake by EGTA could be reversed by adding Ca²⁺ but not Mg²⁺. These results demonstrated that Ca²⁺ is not essential to the initial interaction of phytohemagglutinin with the cell, but does influence amino acid transport which may be a critical preparatory event for later increased protein synthesis.