Glutamine Metabolism in Lymphoid Tissues
When lymphocytes are suitably stimulated either specifically (by an antigen) or non-specifically (by mitogens), they are transformed into a state of high biochemical activity which initiates production of various mediators of immunity including antibodies if they are B-lymphocytes and the mediators of cellular immunity (e.g., lymphotoxin, chemotactic factors, mitogenic factors) if they are T-lymphocytes. To perform this activity lymphocytes require an increased rate of ATP generation and it has generally been assumed that glucose was the only quantitatively important fuel (see Hume and Weidemann 1980). Recently Ardawi and Newsholme (1982) have provided evidence to suggest that other fuels can be utilised by lymphocytes. This suggestion is based on the maximal activities of key enzymes of the energy-producing pathways in lymphocytes, the ability of these cells to utilise glutamine, ketone bodies (3-hydroxybutyrate and acetoacetate) and long-chain fatty acids (oleate and palmitate) (Table 1) and the effects of these fuels on oxygen consumption by lymphocytes. Of these fuels glutamine may be quantitatively the most important.
KeywordsPyruvate Alanine Cardiol Pyrimidine Oleate
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