Pneumococcal vaccination following splenectomy is widely used as prophylaxi
s against overwhelming postsplenectomy infection. There remains controversy
however, over the timing of vaccination. We hypothesized that delaying vac
cination would increase the antibody response. Pneumococcal vaccinations we
re given at designated intervals to rats that had undergone either a sham a
bdominal surgery or splenectomy. Sixty male Sprague-Dawley rats, 250 to 400
g, were divided into three groups for vaccination: I, 1 day postoperativel
y; II, 7 days postoperatively; and III, 28 days postsplenectomy/sham. Serum
antibody levels were then determined by enzyme-linked immunosorbent assay
at 5 and 21 days after vaccination. Immunoglobulin (Ig) levels after delaye
d vaccination at 1 week postoperatively and 1 month postoperatively were si
gnificantly higher than levels from rats vaccinated 1 day postoperatively.
IgM levels after vaccinations 1 week and 1 month postoperatively were also
significantly higher than levels of rats vaccinated 1 day postoperatively (
P < 0.05 for both IgG and IgM). On the basis of these results, we conclude
that delaying vaccination after splenectomy enhances antibody responses.