HYPERTONIC SALINE ENHANCES CELLULAR IMMUNE FUNCTION

Hypertonic saline (HTS) resuscitation improves outcome after trauma. W e studied the effect of HTS on immune function. In vitro T-cell prolif eration of human and rabbit peripheral blood mononuclear cells (PBMC) was doubled at 25 mM increased extracellular Na+ concentrations. Furth er increased hypertonicity (more than 40 mM with human cells, and 80 m M with rabbit cells) caused progressive suppression of proliferation. Human and rabbit monocyte functions (tumor necrosis factor production) were augmented by 300% at 30 mM hypertonicity, indicating that HTS-en hanced accessory cell function of monocytes may cause increased T-cell proliferation. Substitution of HTS with KCl also enhanced T-cell prol iferation, suggesting an involvement of osmotic effects. HTS (up to 30 mM) increased Ca-i(2+) of nonstimulated human PBMC. HTS injection in rabbits increased cell-mediated immune function (delayed-type hypersen sitivity reaction). Our findings suggest that increased plasma osmolal ity may up-regulate cellular immune function. HTS resuscitation of tra uma patients may thus reverse posttraumatic immunosuppression and redu ce the risk of sepsis. (C) 1994 Wiley-Liss, Inc.