The immunostimulant OK-432 enhances liver regeneration after 90% hepatectomy in rats

The effect of reticuloendothelial system activation on liver regeneration after 90% hepatectomy was investigated. OK-432, a killed streptococcal preparation that increases reticuloendothelial system activity, was administered to rats before 90% partial hepatectomy. Pretreated rats showed marked improvement in long-term survival: 87% (18 of 23) survived beyond 42 hr, compared with only 44.2% (24 of 52) of controls (p < 0.05). Survival was determined by means of life-table analysis and regeneration response by means of bromodeoxyuridine labeling index of hepatic DNA. OK-432 pretreatment had significantly increased bromodeoxyuridine labeling index 18, 24, and 42 hr after partial hepatectomy (p < 0.05). The results indicate that reticuloendothelial system activation by OK-432 before 90% partial hepatectomy enhances liver regeneration and improves survival, but these factors may not be related. The improved survival may be because of less infection in macrophage-stimulated animals or more rapid clearance of hypotension-causing vasoactive compounds.