No abstract

carboxylic acid), is a new broad-spectrum cephalosporin antibiotic. Its antibacterial activity in vitro (MIC) is similar, but its bactericidal efficacy superior to that of cephalexin and cephradine. Upon oral administration to mice infected with various bacteria, CGP 9000 is, in general, 2 to 7 times more effective than either cephalexin or cephradine.

The effect of antibody on the fate of Salmonella typhimurium within mononuclear phagocytes (MN) of rabbits was studied in vitro. Monocytes and bacteria were incubated either in absence or presence of antibody. After 45 minutes during which phagocytosis occurred infected cells were washed to remove extracellular bacilli and free antibody. The cells were then reincubated in a medium without addition of antibody, and the interaction between the MN and bacteria was followed, correlating bacterial viability and the morphology of the mixture. The following results were obtained. The anti-Salmonella antibody was not bactericidal even in presence of complement and did not enhance phagocytosis. Regardless of whether antibody was present or absent during phagocytosis, the bacteria appeared to multiply within the cells. When no antibody was present during phagocytosis the infected cells were severely damaged within a few hours of incubation, and extensive extracellular multiplication was dominating. When antibody was present during phagocytosis MN packed with bacteria persisted for a long time. Little or no extracellular growth occurred. It was possible to demonstrate the presence of the antibody within the infected MN, using the fluorescent antibody technique. The antibody appeared as a coat around the bacteria. Antibody entered the cells only during phagocytosis, presumably attached to the bacteria. The active factor of the immune serum was found in the gamma globulin fraction and reacted specifically with the somatic antigen of Salmonella typhimurium. The antiflagellar portion of the antiserum was not involved in the phenomenon described. It is concluded that this antibody protects monocytes against the effect of intracellularly located Salmonella.

In a previous study a technique was reported for the purification and fractionation of human antidextran of a l , 6 specificity produced in a single individual into two antibody populations with distinctly differing affinities for smaller versus larger oligosaccharides (1). The anfidextran, specifically absorbed onto an insoluble dextran (sephadex G-75), was eluted successively with haptens (cf. reference 2) of increasing size. Thus upon extraction of the washed sephadex-antibody complex with isomaltose or isomaltotriose, followed by extensive dialysis of the extract to remove the oligosaccharides, an antibody fraction was obtained which was inhibited readily by small oligosaccharides, while a second fraction, eluted subsequently with isomaltohexaose and dialyzed, consisted of antibody readily inhibitable by the larger oligosaccharides (1). These two fractions, of similar purity with respect to their precipitability by dextran, contained only fast moving 7S gamma globulin,--as did the purified human antidextran obtained by digestion of dextran-antidextran-specific precipitates with dextranase,--and showed by double diffusion in agar complete fusion both with antidextran prepared with dextranase and with each other. These findings supported the earlier suggestion (3) that antibody to one antigenic determinant, the a l , 6-1inked glucose chain in dextran, produced in a single individual, consists of a heterogenous population of molecules that vary with respect to the sizes of their antibody combining sites.Earlier data on these purified antidextran fractions (1) were obtained by quantitative precipitin and inhibition assays using the ninhydrin method with about 3 to 4 #g AbN per analysis. More recently prepared antidextran fractions * Aided by