Analysis of K. pneumoniae by monoclonal antibody: immunohistochemical detection of K. pneumoniae surface antigen injected into mice and rats.

The monoclonal antibody Kp62 recognized surface antigenic determinants of some strains of Klebsiella pneumoniae. The antigen recognized by Kp62 was demonstrated on the bacterial surface using immunoelectron microscopy. Kp62 reacted with K. pneumoniae No. 1 or K. pneumoniae B 5055 and lipopolysaccharide (LPS) from the same bacteria. However, Kp62 was not inhibited by the LPS from Escherichia coli (E. coli) O111:B4 and E. coli O55:B5. Thus, Kp62 might be a useful monoclonal antibody to detect K. pneumoniae and LPS from K. pneumoniae. The possibility to visualize the localization of K. pneumoniae LPS injected into animals using immunohistochemical methods with this monoclonal antibody was examined. It was possible to detect the injected LPS in the spleen of mouse and rat with the monoclonal antibody to K. pneumoniae. In order to detect the early events taking place in the spleen after intravenous injection of LPS, time course of LPS distribution in mice and rats was studied. After 30 min, 2, 4, 8 and 24 h LPS localized in the marginal zone (MZ) in mice and rats, although the degree of LPS positive cells varied. The cells responsible for trapping the injected LPS appeared to be marginal zone macrophages. The early trapping of LPS by marginal zone macrophages was thought to be important for the following immune responses to the injected LPS. Interestingly the antigenic determinant on the injected LPS appeared to last long on or within the cells in the spleen from the injected animals. Such a remaining antigen might be important for the continuous stimulation of B cells by the LPS. With respect to the distribution of red pulp (RP) and white pulp (WP), we found the varied distribution of LPS between mouse and rat, and SPF and conventionally fed (Conv) animals. For example, LPS-positive cells in RP of rat were scarce, while significant degree of LPS-positive cells were observed in mice. And in WP, LPS-positive cells were observed in Conv DA rats, but not in mice or SPF-fed Wistar rats. These results may suggest that the mode of antigen processing may be different in the spleen of rat and mouse or even among the different strain of rats and previous sensitization to the LPS (or the similar antigenic determinants) may lead to the different distribution of LPS in the spleen. The monoclonal antibody specifically raised against K. pneumoniae was shown to be very useful to follow the fate of LPS derived from K. pneumoniae using immunohistochemical method.(ABSTRACT TRUNCATED AT 400 WORDS)