Immune Adjuvancy of Lipopolysaccharide and a Nontoxic Hydrolytic Product Demonstrating Oscillating Effects with Time

Abstract
Since the first reports of immune adjuvancy of endotoxic lipopolysaccharides (LPS) (1, 2), large numbers of such preparations have proven to be effective adjuvants for both soluble and cellular immunogens in a host of laboratory animals (for review, see Neter (3)). Kind and Johnson (4) as well as Franzl and McMaster (5) investigated the effect of time of LPS treatment on the primary immune response. In earlier investigations on radioprotective properties of LPS, we observed a unique time-dependent survival pattern of lethally irradiated mice pretreated with LPS (6). It was established that two optimal time intervals, peaking at -1 to -3 and -8 to -12 days, existed. A closely parallel time-dependent radioprotective profile of the nontoxic, polysaccharide-rich fraction (PS)3 of LPS could also be established. Quite recently a similar time-dependent, LPS-induced protection against TA3-Ha tumors in mice was also observed by us (7).