Three enterotoxigenic Escherichia coli (ETEC) strains (coded 62, 104, and 567/7) isolated from piglets with neonatal diarrhea produced only a thermostable enterotoxin. Although these strains showed mannose-resistant microhemagglutination (MRMH), the responsible factor was serologically different from the known hemagglutinating colonization factors from porcine strains (K88, K99, and F41). Bacterial cells from these strains adhered to HeLa cells and pig brush borders. Electron microscope studies revealed the presence of fimbria-like structures on bacterial cells grown at 37C but not on cells grown at 18C. The antiserum prepared from partially purified fimbrial antigen (provisionally called F42) inhibited chicken erythrocyte MRMH caused by these strains as well as adherence of strain 567/7 to HeLa cells and to pig brush borders. These data taken together suggest the existence of a new hemagglutinating adhesin that is different from those so far described for porcine ETEC.

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Forty amikacin-resistant strains of Serratia marcescens isolated from four different hospitals (A, B, C, and D) were examined for modifying enzymes and plasmids. Twenty-one of the isolates produced acetyltransferase that modified amikacin. Eighteen of the 21 acetyltransferase-bearing isolates were from different inpatients in hospital A and the other three were from hospital C. Amikacin resistance was mediated by conjugative plasmid of 24 megadaltons in 15 of the 18 acetyltransferase-bearing isolates of hospital A and by nonconjugative plasmids, derivatives of the 24-megadalton plasmids, in the remaining three isolates of the same hospital. The 24-megadalton plasmid determined aminoglycoside acetyltransferase (6') IV. This plasmid-borne enzyme conferred amikacin resistance on S. marcescens but not on Escherichia coli K12. The frequency of transfer of the 24-megadalton plasmid from the S. marcescens isolate to E. coli K12 by conjugation was approximately 10^-7 (transconjugants/donors) and was 0.1% of that between E. coli strains. In acetyltransferase-bearing isolates from hospital C, the enzyme was mediated by a nonconjugative plasmid in one case and could not be associated with a plasmid in the remaining two cases. Neither enzymes nor plasmids could be associated with amikacin resistance of the isolates of the other two hospitals.

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The fecal microflora of nine rural healthy Japanese and eight urban healthy Canadians was examined. The two populations ate typical Japanese and western diets, respectively. The numbers of eubacteria (P<0.01), bifidobacteria (P<0.05), bacilli (P<0.01), lactobacilli and veillonellae and the frequency of occurrence of bifidobacteria were higher in the Japanese than in the Canadians. Higher numbers of bacteroides and lecithinase-negative clostridia were found in the Canadians. Twenty-three genera and over 75 species or biovars were isolated from the feces of Japanese and 18 genera and over 66 species or biovars from the Canadians. The numbers of Bacteroides vulgatus (P<0.05), Clostridium coccides (P<0.001), and C. tertium (P<0.05) and the incidence of B. uniformis (P<0.01), C. innocuum (P<0.05), and Bacillus spp. (P<0.01) were significantly lower in the Japanese than in the Canadians. In contrast, the numbers of Eubacterium aerofaciens (P<0.001), and the incidence of Bifidobacterium adolescentis biovar b (P<0.01) and Bacillus subtilis (P<0.01) were significantly higher in the Japanese than in the Canadians. These findings suggest that significant reductions in anaerobic grampositive bacilli and increased numbers of bacteroides and clostridia in the feces were induced by the intake of a western diet.

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Sera from each of five preselected groups of patients with acquired immune deficiency syndrome (AIDS), AIDS-related complex (ARC), hemophilia, adult T-cell leukemia (ATL), and healthy controls were examined for antibodies to human T-cell leukemia (T-lymphotropic) virus type-I (HTLV-I) and HTLV-III by indirect immunofluorescence (IF) and radioimmunoprecipitation (RIP) methods. All sera from five patients ith AIDS, ARC, and hemophilia reacted at titers from 1: 512 to 1: 5, 120 with fixed H9/HTLV-III cells by IF but not with fixed MT-1 cells carrying HTLV-I. Similarly, sera from patients with AIDS, ARC, and hemophilia precipitated HTLV-III-specific polypeptides of 120K, 46K, and 24K. In contrast, sera from five patients with ATL did not react with fixed H9/HTLV-III cells, but reacted with fixed MT-1 cells. Moreover, HTLV-I-specific polypeptides of 68K, 28K, and 24K were precipitated with sera from ATL-patients but not with anti-HTLV-III-positive sera. Recently, we infected HTLV-I-carrying MT-4 cells with HTLV-III and provoked strong cytopathic effects. This system enabled testing for neutralizing antibodies to HTLV-III. Neutralizing titers to HTLV-III of five anti-HTLV-III-positive sera ranged from 1:720 to 1:9, 000. In contrast, all five seronegative controls showed no or only low reactivity to HTLV-III envelope (1:80 and 100). However, three out of five anti-HTLV-I-positive sera exhibited weak cross-reactivities with HTLV-III. The reactivities were expressed as <1: 160, except for one case (1:720). They were considered to be nonspecific since they were negative for HTLV-III antibodies in the radioimmunoprecipitation studies.

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The budding process and fine structure of lymphadenopathy-associated virus (LAV), were studied by indirect immunofluorescence (IF) and electron microscopy (EM). By IF, LAV antigen was seen to be distributed focally within infected CCRF-CEM cells. Consistent with this finding, electron micrographs showed that LAV particles occurred in a focally aggregated state in a restricted area of the surface of the infected cells. LAV particles possessed bar-shaped, dense and central or eccentric cores. In addition, two or more cores were occasionally observed in one virus particle, or the cores were sometimes absent when thin sections were examined. The envelope of the virus particles had an irregular structure, although LAV particles were approximately spherical.

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The role of humoral and cellular immune responses in the initiation and maintenance of autoimmune thyroiditis was investigated in mice immunized with syngeneic thyroid extract and Klebsiella O3 lipopolysaccharide (KO3 LPS) as an adjuvant. The transfer of spleen cells from hyperimmunized mice to 400R-irradiated syngeneic mice produced definite lesions in the thyroid glands, whereas the transfer of immune sera failed to do so. No lesions were induced in normal intact mice by the same transfer of sera and spleen cells from hyperimmunized mice. It was suggested that the induction of thyroiditis by immunization using KO3 LPS adjuvant is primarily due to cell-mediated immunity and that pretreatment of mice by X-irradiation is essential for production of the lesions. The role of X-irradiation in the induction of thyroiditis was discussed.

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Unfractionated human peripheral blood mononuclear cells produce a small amount of interleukin 2 (IL 2) by stimulation with a monoclonal anti-T3 antibody (OKT3) in vitro. The IL 2 production could be greatly augmented by the addition of a phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate (TPA).
In the presence of TPA, the T cell enriched fraction deprived of macrophages did not produce IL 2, but the T cells pulse-incubated with OKT3 and reconstituted with macrophages efficiently produced IL 2 in subsequent culture in the presence of TPA as did T cells reconstituted with OKT3-pulse-incubated macrophages. The stimulating effect of OKT3 in the presence of macrophages was inhibited dose-dependently by the addition of immunoglobulins, particularly by mouse IgG2_a which is the same isotype as that of the OKT3 antibody, showing that it inhibits by blocking the binding of OKT3 to Fc receptors on macrophages. The same extent of IL 2 production was induced in T cells when paraformaldehyde-fixed macrophages were substituted for intact macrophages. Remarkable IL 2 production was also induced by OKT3 when latex beads coated with rabbit anti-mouse IgG2_a antibody and TPA were added to the culture. It was confirmed that the production induced by these stimulations was due to an increase of IL 2 mRNA. These results show that effective signals for IL 2 production are generated by efficient crosslinking of T3 molecules which results from multi-interaction of T3 molecules on the T cell membrane and anti-T3 antibody molecules on macrophage membrane or on the surface of the latex particle.

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A hybridoma clone secreting rat monoclonal antibody (MAB) designated as 3F3.5F and which reacted with a population of activated tumoricidal mouse peritoneal macrophage (MΦ) was produced by the fusion of mouse myeloma cells with rat spleen cells immunized against adherent BCG-activated mouse peritoneal exudate cells (adherent BCG-PEC). The antibody was cytotoxic and of the rat IgM class. The specific reactivity of the antibody with mouse primary cells and cell lines was examined by complement-dependent cytotoxicity and indirect immunofluorescence flow cytometry analysis. The antibody was found to bind to about 40% of the adherent BCG-PEC activated in vivo and elicited peritoneal macrophages activated in vitro by lymphokine and lipopolysaccharide (LPS), to about 35% of polymorphonuclear neutrophils (PMN) 15hr after intraperitoneal injection of BCG, to about 30% of bone marrow cells from BCG-infected mice, to about 10% of P815 mastocytoma cells and to thioglycollate-induced PEC to some degree. It did not bind to other cells tested including BCG-induced peritoneal lymphocytes, non-tumoricidal PEC, thymocytes, spleen cells, resting bone marrow cells from normal mice, lymphomas, myelomas, fibroblasts, or macrophage-cell lines. Pretreatment of adherent BCG-PEC with MAB 3F3.5F and rabbit complement caused a considerable decrease in tumor cytotoxicity toward P815 cells, but the same pretreatment of non-adherent BCG-PEC had no inhibitory effect on natural killer activity for YAC-1 cells.

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