Inhibition of cellular cytotoxicity of leukocytes for herpes simplex virus-infected cells in vitro and in vivo by intralipid.

The effect of intralipid, a lipid emulsion used in total parenteral nutrition, on cellular cytotoxicity for herpes simplex virus (HSV)-infected cells was analyzed. In vitro, intralipid inhibited antibody-dependent cellular cytotoxicity (ADCC) of lymphocytes, monocytes-macrophages, and polymorphonuclear leukocytes and natural killer cytotoxicity of lymphocytes for radiolabeled HSV-infected liver cells. This was due to an effect on the leukocytes, rather than on the target cells. Intralipid did not affect leukocyte viability but inhibited the expression of leukocyte Fc receptors necessary for cytotoxicity. In vivo, intralipid inhibited murine ADCC and completely nullified the protection against lethal infection with HSV in neonatal mice afforded by the administration of human leukocytes and antibody. These data suggest that high levels of circulating intralipid may interfere with antiviral immunity in humans and predispose hosts who are already compromised to severe viral infections.