AJP - Cell Physiology, Vol 266, Issue 2 C541-C551, Copyright © 1994 by American Physiological Society
19F-NMR study of primary human T lymphocyte activation: effects of mitogen on intracellular pH
M. Bental and C. Deutsch
Department of Physiology, School of Medicine, University of Pennsylvania, Philadelphia 19104.
Intracellular pH of purified human T lymphocytes was studied using nuclear
magnetic resonance (NMR) spectroscopy under physiological conditions. In
this paper we introduce a new improved 19F-NMR pH probe,
2-amino-3,3'-difluoroisobutyric acid (vic-difluoro-alpha-methylalanine),
which has a pKa of approximately 7.0, sensitivity of 0.83 ppm/pH, is
noncytotoxic, and provides better signal-to-noise ratio for intracellular
pH determinations. Quiescent and stimulated lymphocytes display different
homeostatic intracellular pH values. Quiescent cells maintain intracellular
pH of 7.04 +/- 0.03 at extracellular pH values between 6.9 and 7.3, and
stimulated cells maintain intracellular pH of 7.25 +/- 0.05 at
extracellular pH values between 7.0 and 7.5. Stimulation with ionomycin
plus phorbol 12-myristate 13-acetate leads to intracellular alkalinization
within 90 min, reaching the more alkaline steady-state value of 7.25 within
7-10 h. Proliferation, but not viability, of lymphocytes is dependent on
extracellular pH in the range of 6.4-8.0, and this dependence is not due to
limiting interleukin-2 elaboration. The mechanisms of pH regulation and the
possible implications of a permissive pH for T lymphocyte proliferation are
discussed.
