Abstract
Summary
HEPES [4-(2-hydroxyethyl)-1-piperazinyl-ethane-2-sulfonic acid] was studied as a possible hydrogen ion buffer in cultures of human peripheral blood lymphocytes. It was found the HEPES fulfills the demands required, namely:
1. It is not toxic to lymphocytes within the range of concentration (10-40 mM), which ensures excellent buffering capacity.
2. It does not itself stimulate lymphocytes.
3. It essentially does not affect the rate of lymphocyte stimulation induced by the nonspecific stimulant (phytohemagglutinin), antigen (tuberculin), or in mixed allogeneic cultures.
In comparison with bicarbonate buffer, HEPES offers greater buffering capacity within the physiological range of pH. Due to this, HEPES-buffered media maintained constant pH even in very crowded cultures, ensuring better cell survival and stimulation. The maximal stimulation of lymphocytes induced by PHA was observed in HEPES-buffered cultures at a pH range of 7.4-7.6.
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