There are limited studies of glutamine and B-lymphocyte function. It was demonstrated that differentiation of B lymphocytes into antibody producing cells in vitro is dependent upon glutamine and increases over the physiological range of glutamine concentration (Crawford and Cohen, 1985).
Monocytes and Macrophages
Spittler et al. (1995, 1997) demonstrated that the expression of various molecules involved in phagocytosis and in antigen presentation on the surface of human blood monocytes is influenced by the concentration of glutamine in which the cells are cultured. This was linked with increased function, including increased phagocytosis and antigen presentation, with increasing glutamine availability (Spittler et al., 1995, 1997). Other studies have demonstrated that glutamine availability influences phagocytosis by cultured murine macrophages (Parry-Billings et al., 1990a; Wallace and Keast, 1992). Glutamine also influences production of cytokines by monocytes and macrophages. For example, Wallace and Keast (1992) demonstrated that glutamine increased the IL-1 response to murine macrophages to bacterial lipopolysaccharide (LPS). Similarly, rat macrophages showed increased production of tumor necrosis factor (TNF)-a with increasing glutamine availability (Murphy and Newsholme, 1999). Glutamine addition to the culture medium of rat macrophages
increased LPS-stimulated IL-1 and IL-6 gene expression and secreted protein (Yassad et al., 2000). Glutamine also increased LPS-stimulated IL-8 production by cultured human blood monocytes (Murphy and Newsholme, 1999).
Wells et al. (1999) reported that feeding mice a diet containing about 2.5 times the normal amount of glutamine increased the production of TNF-a, IL-10, and IL-6 by LPS-stimulated macrophages.