Endotoxin-induced appearance of peroxidase-positive cells in the white pulp of the mouse spleen.

Endotoxin (1-10 microgram intravenously) increased the number of strongly peroxidase-positive cells in the white pulp of the mouse spleen, demonstrable by the Graham-Karnovsky technique. The increase was greatest after 10 h, the cells being found most frequently around the central vessels of the white pulp. The appearance of such cells at this critical immunological site may relate to the known adjuvant activity of endotoxin in promoting immune responses against protein antigens.