Glycyl-glutamine improves in vitro lymphocyte proliferation in AIDS patients.

ABSTRACT

BACKGROUND: Glutamine (Gln) is a major nutrient for rapidly proliferating cells. Unlike glutamine itself, the dipeptide glycyl-glutamine as a source for Gln is stable in aqueous solutions ex vivo. In order to evaluate the possible therapeutic role of glycyl-glutamine on lymphocyte proliferation we investigated its influence on lymphocytes of AIDS patients and healthy controls under stimulation with different mitogens. MATERIAL AND METHODS: Lymphocytes were collected from 11 adult patients suffering from AIDS according to the CDC definition and from 7 adult healthy donors. Glutamine (Gln) and glycyl-glutamine (GlyGln), respectively, were added to cell cultures at concentrations between 0 and 1.0 mmol/l. ConA or SAC served as T or B cell mitogens, respectively. Plasma amino acid levels were determined. RESULTS: Proliferation upon ConA-stimulation with GlyGln-supplementation was similar to Gln-supplementation and peaked dose dependently at 1.0 mmol/l. When SAC was used Gln seemed slightly superior to GlyGln with a peak at 0. 4 mmol/l but the results did not reach the level of statistical significance. An identical response pattern was demonstrated in HIV-patients, however at lower absolute proliferation rates. Normal values could not be restored. Overall, the use of either source of glutamine in equimolar concentrations did not result in major differences of proliferation. Glutamine and glycin plasma levels did not differ between HIV patients and controls. CONCLUSION: GlyGln can be used as a substitute for Gln with regard to lymphocyte proliferation. Lymphocytes from AIDS patients show, as controls do, an enhanced proliferation under supplementation either glutamine source. Supplementation of GlyGln might enhance lymphocyte proliferation and thus improve immunity.