Analyses have been carried out on lipopolysaccharides (LPS) from 14 strains of Enterobacter cloacae representing different O serotypes. All of the products appeared to have a composition and architecture typical of enterobacterial LPS, but points of interest include the absence of phosphate residues from the core oligosaccharide, the presence of both L-glycero-D-mannoheptose and D-glycero-D-mannoheptose (ratio usually about 4:1), and the presence in lipid A of small amounts of fatty acids with odd numbers of carbon atoms (mainly C₁₃) in addition to tetradecanoic acid and 3-hydroxytetradecanoic acid. Monosaccharides identified as components of polymeric fractions from the LPS were glucose, galactose, mannose, rhamnose, glucosamine, galactosamine, fucosamine, and galacturonic acid. Most polymeric fractions also probably contained an O-acetyl substituent. Closely similar chemotypes found for the polymeric fractions from the LPS of cross-reacting serotypes support the view that these fractions contain the O-antigenic determinants and represent the side chains of the LPS.

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The alteration of hepatic drug-metabolizing enzyme activities in mice given Salmonella endotoxin by single or multiple intraperitoneal injections was investigated. An essentially the same biphasic, early and late phase, endotoxin tolerance was observed in the animals receiving a single injection of endotoxin or repetitive daily injections. The results of reciprocal cross tolerance tests using lipopolysaccharide and free lipid A preparations derived from Salmonella minnesota, Salmonella typhimurium, E. coli, Pseudomonas aeruginosa, and Chromobacterium violaceum suggested that lipid A moiety plays an important role in the induction of early endotoxin tolerance to endotoxin response.

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The mechanism and kinetics of intracellular growth of Rickettsia tsutsugamushi were investigated by electron microscopic observations, parallel with quantitative analysis by counting the rickettsiae seen in electron micrographs and by plaque assay for infectivity of the culture. The observations demonstrated the existence of electron-less dense and -dense types of rickettsiae in the early stage of infection, binary fission and the process of release of the microorganisms in the host cell cytoplasm and from the cell surface, formation of abnormally long rickettsiae, and the process of lysis of the host cell in the later stage of infection with vacuole formation between the inner and outer leaflets of the host cell nuclear membrane. Separate titrations of infectivity of the cells and the culture fluid showed a very slow increase in infectivity in the culture fluid compared with the intracellular titer, suggesting that the progeny rickettsiae stay in the cell or at the cell surface for a relatively long period. Doubling time of the rickettsia was found to be about 9hr.

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Glucose interfered with the inhibitory action of hydrophobic compounds, such as n-octanol, diphenylamine and 2-tert-butylphenol, during L-alanine-initiated germination of Bacillus subtilis spores. The action of glucose on the action of the hydrophobic compounds was not competitive, and the binding affinity of glucose was not essentially affected by the hydrophobic compounds, indicating the presence of separate binding sites for glucose and the hydrophobic compounds. The binding affinity of D-alanine, a competitive inhibitor of L-alanine, was not affected by the hydrophobic compounds, indicating separate binding sites for D-alanine and the hydrophobic compounds. A possible arrangement of the binding sites for glucose and for the hydrophobic compounds in relation to those for L- and D-alanine on the spores is discussed.

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Beige mutant (bg/bg) mice with Chediak-Higashi syndrome (CHS) were much more sensitive to virulent Salmonella enteritidis No. 11 strain than parental C57 BL/6 (+/+) or heterozygous (bg/+) mice, and they had weaker bactericidal activity against the organisms. Muramyl dipeptide (MDP) and N^α-(N-acetyl-muramyl-L-alanyl-D-isoglutamyl)-N^ε-stearoyl-L-lysine [MDP-Lys(L18)], a synthetic derivative of MDP, failed to confer any protection against the infection, but the MDPs showed some ability to stimulate the bactericidal activity in the peritoneal cavities and spleens of these mice. The bactericidal effect of MDP-Lys(L18) was dose-dependent, and the greatest effect was seen when it had been injected 24hr before the infection. Multiple injections of MDP were much more beneficial than a single injection.
Previous injection of N², O²'-dibutyryl guanosine 3':5'-cyclic monophosphate (DB-cGMP) improved the impaired bactericidal capacity in beige mice, but the simultaneous injection of N⁶, O²'-dibutyryl adenosine 3':5'-cyclic monophosphate (DB-cAMP) with DB-cGMP abolished the effect of DB-cGMP. The augmentation of bactericidal capacity by MDP-Lys(L18) was not affected by the injection of either DB-cGMP or DB-cAMP, suggesting that the effect of the MDPs was not related directly to cyclic nucleotide regulation in beige mice.

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Murine anti-human class II antibodies were shown to cross-react with polymorphic determinants of murine class II antigens. The cross-reacting antibodies were raised in B10.S(9R) mice by immunizing with human nylon wool adherent cells (Ad cells) from peripheral blood leukocytes. The B10.S(9R) antihuman Ad cell antiserum bound to the molecules consisting of two chains with molecular weights of 35K and 28K dieters which were purified with a lentil-lectin column. The B10.S(9R) anti-human class II antiserum was also revealed to contain two distinct cross-reacting antibodies with polymorphic determinants of murine class II antigens coded for by the I-A subregion of the H-2. One is specific for a determinant of class II molecules coded for by I-A^{b, d, q}, and the other seems to be specific for class II molecules coded for by I-A^{a, k, r}.

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Sensitive methods of an enzyme-linked immunosorbent assay (ELISA) using red blood cells (RBC) have been developed and were applied to the detection of anti-sheep red blood cell (SRBC) heterophile antibodies (Ab) present in sera of Schistosoma japonicum (SJ)-infected mice. The indirect hemagglutination test (IHA) was used for the purpose as well. By these methods a significant increase in the heterophile Ab levels was demonstrated in the mice particularly after 6-10 weeks of infection. The heterophile Ab in SJ-infected mice were predominantly immunoglobulins resistant to 2-mercaptoethanol treatment and had temperature-independent reactivity. In an attempt to investigate the immunological specificity of the heterophile Ab, various absorption tests were performed; Davidsohn's differential absorption test revealed that the heterophile Ab were distinct from Forssman antibody, Paul-Bunnell antibody and heterophile agglutinins known to appear in serum sickness. The heterophile Ab were absorbed only with SRBC and goat red blood cells, not with other species of RBC such as human O Rh-, O Rh+, A Rh+, B Rh+, mouse, ox, chicken, horse, rabbit, guinea pig, and rat RBC, or syngeneic tissue homogenates including brain, lung, liver, spleen, kidney, muscle, and thymus. This heterophile antibody response is not a consequence of a specific immune response directed to the antigens of SJ parasites, since absorption of the heterophile Ab with SJ adult worms or an egg preparation did not reduce the heterophile Ab level.

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