The early uptake of radioactive calcium by human lymphocytes treated with phytohaemagglutinin

Abstract

Phytohaemagglutinin (PHA) is presumed to react initially with receptors on the surface of lymphocytes and may cause permeability or other changes in the lymphocyte cell membrane. The uptake of radioactive calcium (⁴⁵Ca) by normal human blood lymphocytes increased within 38 minutes of adding PHA, and there was little further increase in ⁴⁵Ca uptake between 38 and 78 minutes. This effect of PHA was demonstrated at pH 7.2 and pH 7.5. There was no detectable uptake of ⁴⁵Ca by human erythrocytes under the same conditions, with or without PHA. The observations are compatible with an early uptake of calcium when PHA initiates cell division, analogous to the role of calcium in muscle and secretory cells.