Influence of hydroxyethyl starch on humoral and cell-mediated immune responses in mice.

The immunotoxicity of hydroxyethyl starch (HES), a reagent used in leukocytapheresis or as a plasma expander, was assessed. HES did not significantly alter host resistance to Listeria monocytogenes or Streptococcus pneumoniae. HES (4-32 ml/kg), as well as a physiological saline solution (32 ml/kg), did inhibit the in vitro lymphoproliferation of spleen cells from mice intravenously injected 1 hour prior to removal of the spleens; the proliferation induced by a T-cell and B-cell mitogen was suppressed. However, this suppression was transient, in that, HES and saline injections given 4 and 24 hours prior to removal of the spleens produced no significant inhibition. Unlike the HES effects on lymphoproliferation, HES did suppress the in vivo humoral immune response to sheep erythrocytes (SRBC) when given 24 hours prior to antigen, but this inhibition was obtained only with the 32 ml per kg dose. Interestingly, a similar dose of mouse albumin significantly enhanced the response. In vitro analysis of humoral and cell-mediated immune responsiveness with in vivo treated spleen cells produced results that were not dose dependent. Although HES was more suppressive than saline, both saline and HES were inhibitory. The lack of a dose-dependent effect suggests that the in vitro analysis of in vivo treated cells was not a good index of their in vivo reactivities. The greater variability and apparent sensitivity of the in vitro analysis probably reflect the transient effects of in vivo dilution of serum factors by relatively large intravenous injections and/or the transient effects of injection trauma.