Rabbit polymorphonuclear leukocyte chemotactic factor generated in vivo by Bacteroides fragilis lipopolysaccharide. II. Antigenic and biologic properties.

Preparations of the polymorphonuclear leukocyte (PMN) chemotactic factor isolated from lipopolysaccharide (LPS)-induced inflammatory exudate in rabbits were immunogenic in guinea pigs. Complete fusion of the precipitation lines produced against anti-CF by LPS-CF (molecular weigth 16,000) and material eluted on Sephadex G-200 columns with molecular weights (MW) of 68,000, 16,000 and 7,000 was found. Also, the chemotactically active material with MW of 68,000 and 7,000 eluted on G-75 columns after fractionation of the fraction of MW 16,000 from the G-200 eluate was antigenically identical to LPS-CF in double diffusion in agar. Normal rabbit serum (NRS) incubated with LPS, LPS-induced wound chamber exudate and NRS alone gave lines of precipitation against the anti-LPS-CF sera identical to that of LPS-CF. The capacity of LPS-CF to attract PMNs was significantly higher than that of LPS, and a peak in the number of PMNs in the exudate of wound chambers implanted in rabbits was found 4 h after the local injection of LPS-CF. When injected intraperitoneally in C5 deficient mice, LPS-CF stimulated a PMN migration which was only slightly below that in C5 normal mice. Antisera to LPS-CF inhibited the chemotactic activity of LPS-CF as well as that of LPS-NRS when the supernatants were tested using the Boyden's technique. Also, preincubation of PMNs with LPS-CF suppressed the migration towards a chemotactic gradient of LPS-CF molecules of these PMNs.