Delayed vaccination does not improve antibody responses in splenectomized rats experiencing hypovolemic shock

Delayed vaccination after splenectomy has been shown to increase the antibo dy response in normotensive rats. The purpose of this experiment was to stu dy the effect of timing of vaccination on antibody responses in rats underg oing splenectomy and experiencing hypovolemic shock. Sixty male Sprague-Daw ley rats weighing 250 to 400 g underwent either a sham abdominal surgery or splenectomy after a 30-minute period of controlled hypovolemic shock. All rats then received pneumococcal vaccinations one day, 7 days, or 28 days po stoperatively. Antibody levels were determined by enzyme-linked immunosorbe nt assay 3 weeks after vaccination. Results were compared by analysis of va riance. Animals vaccinated one day postoperatively had similar or higher an tibody responses than did rats receiving delayed vaccinations after 7 or 28 days. These results were similar for immunoglobulins G and M and more impo rtantly were consistent for animals undergoing splenectomy and sham operati ons. Delayed vaccinations failed to improve antibody responses when hypovol emic shock preceded splenectomy. We propose that this is the result of comp lex cytokine responses to hypovolemic shock. These responses have been stud ied extensively in the setting of septic shock but not in the setting of hy povolemic or hemorrhagic shock.