Practice question

RPMI 1640 medium formulated by George Moore and colleagues at Roswell Park Memorial Institute in 1966 specifically for suspension culture of human leukocytes and hematopoietic cells, exhibits unique formulation low in calcium 100 mg per L and magnesium reduced to minimize aggregation, enriched with vitamins and reduced glutathione. Crucially it relies on sodium bicarbonate buffer system 2.0 g per L interacting with gas phase carbon dioxide via equilibrium CO2 plus H2O equilibrates to H2CO3 equilibrates to H+ plus HCO3- described by Henderson-Hasselbalch equation. Five percent CO2 atmosphere providing partial pressure approximately 38 mmHg at sea level sustains pH 7.2 to 7.4 optimal for lymphocyte proliferation, balancing bicarbonate without causing alkaline drift seen at 1 percent or acidosis at 10 percent. Incubators equipped with IR CO2 sensors, HEPA filtration, humidity pans maintain constant conditions at 37 Celsius. Many hybridoma fusions, peripheral blood mononuclear cells and leukemia lines like Jurkat thrive in this buffering regime. Some media such as DMEM with higher bicarbonate 3.7 g per L require 10 percent CO2, but RPMI standard remains 5 percent providing physiological resemblance to venous blood CO2 tension.