Injection of viable cells of Flavobacterium meningosepticum at doses of 10⁶ colony-forming units/eye caused ophthalmia in rabbits' corneas.
Elastase, free of protease activity, was partially purified from broth cultures of F. meningosepticum ATCC12535 and TMS516. The optimum pH of the elastase activity was about 8.0. The activity was suppressed by Ni, Zn, Co, EDIA, and o-phenanthroline, and accelerated by Cu and Fe.
The minimum dose of the elastase causing ophthalmia in the eyes of rabbits was 5μg/eye (0.065 elastase units). The minimum lethal dose of the elastase for suckling mice by intracerebral injection was 0.4μg (0.0052 elastase units)/suckling mouse, and its minimum lethal dose for adult mice by intraperitoneal injection was 740μg/mouse (9.52 elastase units).

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The advantage of using cycloheximide for cultivating Mycobacterium lepraemurium in cell culture was further demonstrated. Continuous multiplication of the bacillus in successive subcultures was obtained in MFP, HEp-2 and Vero cells maintained in culture medium containing 0.1μg of cycloheximide per ml. Growth characteristics were comparable to those observed in the cultures of A31 cells previously reported. The procedure was simple and convenient. Comparable results, however, have not been obtained in cultures of other established cell lines, HeLa 229, L, MDCK, and Neuro-2a.

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Dengue type 2 virus (D2V) infection in cultured human monocytes was studied. D2V permissiveness of the monocytes was enhanced when the cells were inoculated with D2V in the presence of either polyclonal or type-specific monoclonal anti-dengue antibody. The enhancement of D2V permissiveness mediated by the antibodies was more clearly demonstrated when the monocytes had been treated with trypsin before virus inoculation, though treatment of the cells with trypsin alone decreased D2V permissiveness. The enhancement of infection by type-specific neutralizing monoclonal antibody suggests that the D2V particles possess at least two antigenic determinants closely associated with virus infectivity.
Infectious center assays revealed that the infection enhancement in the presence of the antibodies was due primarily to an increase in the number of D2V-infected cells, and that only a small proportion of the monocyte population supported D2V replication. The virus-permissive monocytes did not bear HLA-DR antigens on their cell surface. The presence of nonadherent lymphocytes in the monocyte cultures before D2V inoculation did not affect the D2V permissiveness of the monocytes.
Treatment of cultured monocytes with the synthetic adjuvants N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) and its lipophilic derivative, [B30]-MDP, did not significantly affect the D2V permissiveness of the cells.

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Human T-lymphoblastoid cell lines RPMI 8402, MOLT-3, and CCRF-CEM were treated with interferon (IFN) to determine if the treatment would result in the disappearance of cellular terminaldeoxynucleotidyltransferase (TdT), a possible differentiation marker for T-lymphocytes. Incubation of RPMI 8402 cells in the presence of IFN preparation caused a decrease in the number of TdT-positive cells and in TdT activity of the cell extract. The inhibition of cell multiplication was dose dependent. The anticellular effect of IFN preparation was cytostatic, not cytocidal. The IFN preparation modified neither the TdT content nor proliferation of MOLT-3 and CCRF-CEM cell lines. The effects of IFN preparation thus varied with the cell line.

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Hepatitis B virus (HBV) DNA was detected by direct spotting of alkali-denatured serum on a nitrocellulose filter and molecular hybridization with cloned HBV DNA as the probe. Measurement of the autoradiographic signals as the intensity of hybridization allowed the quantitation of HBV DNA content in serum specimens in reference to cloned HBV DNA. Direct spotting of denatured serum was approximately three times as sensitive as the conventional method in which proteinase-treated serum was extracted with phenol-chloroform. The intensity of hybridization with 25 specimens of HB virion concentrates correlated well with DNA polymerase activity (r=0.89, P<0.01).

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The activity of fibroblast-derived thymocyte activating factor (FTAF) of the guinea pig was measured, and the factor was partially characterized. The FTAF activity was heat labile, and destroyed by treatment with trypsin, chymotrypsin, and Streptomyces griseus protease, suggesting the protein nature of FTAF. FTAF bound to DEAE-Sepharose CL-6B in Tris-HCl buffer at pH 8.0, and was eluted with 0.1-0.2M NaCl. FTAF was absorbed with Blue Sepharose CL-6B. The factor bound to a hydroxylapatite column in 10mM phosphate buffer and was eluted in two major fractions, one fraction with 40mM phosphate buffer, the other with 70-110mM phosphate buffer. Finally, FTAF did not have as much effect on the proliferation of lymph node T cells as T-cell-activating monokines which exhibited marked stimulating effects on both T lymphocytes and thymocytes.

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The isotype specificity of Fc-receptors for IgG (Fcγ-Rs) on normal guinea pig splenic B and T cells was determined by a rosette assay using sheep erythrocytes sensitized with either homologous IgG1 or IgG2 anti-sheep erythrocyte antibody [EA(IgG1) or EA(IgG2)]. Approximately 70%, of the lymphocytes in the highly purified B-cell fraction could form rosettes with EA(IgG2), and 55% of the cells with EA(IgG1). Inhibition experiments with soluble complexes of IgG1 or IgG2 antibody with ovalbumin demonstrated that approximately 20% of the EA(IgG2) rosette-forming B cells bore the Fcγ-R monospecific for IgG2, whereas 80% of the cells had two distinct Fcγ-Rs simultaneously; one monospecific for IgG2 and the other bispecific for IgG1 and IgG2. The existence of a B cell bearing the Fcγ-R monospecific for IgG1 was not definitively demonstrated in the B-cell fraction. In the T cell-enriched fraction, approximately 40%, of the cells could form rosettes with EA(IgG2). The EA(IgG1) rosette-forming cells, however, comprised only 6% of the total cells, indicating that most of the EA(IgG2) rosette-forming T cells bear essentially the Fcγ-R monspecific for IgG2 alone.
The results obtained revealed that guinea pig splenic lymphocytes bear two distinct Fcγ-Rs, which are not equally distributed on the B- and T-cell populations and also on their respective subsets.

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The properties of TAS-1D3, a tuberculin-active substance purified from the cell extract of Mycobacterium bovis BCG, were studied in vivo and in vitro. In the delayed hypersensitivity skin reaction, TAS-1D3 showed far more potent activity than tuberculin purified protein derivative (PPD) in guinea pigs sensitized with BCG vaccine. This was consistently observed from 6 to 24 weeks after sensitization. The histological findings of the skin reaction to TAS-1D3 were similar to those of the reaction to PPD. Moreover, TAS-1D3 induced well both thymidine incorporation and the production of migration inhibitory factor (MIF) by the spleen cells from guinea pigs sensitized with BCG vaccine. In contrast, TAS-1D3 showed weaker activity than PPD in guinea pigs sensitized with either heat-killed M. tuberculosis Aoyama B or heat-killed M. tuberculosis H37Ra, and it weakly stimulated the spleen cells from animals sensitized with M. tuberculosis Aoyama B to incorporate thymidine and to produce MIF.

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