Natural killer (NK) and antibody-dependent cellular cytotoxicity (ADCC) activities can be differentiated by their different sensitivities to interferon and prostaglandin E1

Though purported to be identical cells (or in identical populations of cells), the natural killer (NK) cell mediating spontaneous natural cytotoxicity and the killer (K) cell mediating antibody-dependent cellular cytotoxicity (ADCC) may not be totally identical, at least in susceptibility to regulation by the immunomodulators prostaglandin E₁ (PGE₁) and interferon (IFN). We demonstrate here that NK cells are always enhanced by IFN, while K cells are inhibited from binding targets, resulting in fewer effectors at optimal concentrations of antibody. Only at 10- to 100-fold suboptimal concentrations of antibody is ADCC activity enhanced. As measured by magnitude of inhibition and dose-response titration, ADCC activity is less sensitive to the effects of PGE₁ than is NK activity in the⁵¹Cr release assay and single-cell assay. After overnight incubation with or without PGE₁, whatever sensitivity ADCC activity had to PGE₁ is lost. However, NK cells incubated in the presence of PGE₁ overnight are still sensitive to inhibition. Indomethacin boosts NK activity without having any effect on ADCC activity. Finally, NK activity is substantially reduced by overnight incubation of cells at room temperature, which has no effect on K cells.     

Use of multivariate statistical methods to identify immunochemical cross‐reactants

Quantitative competition immunoassays with appropriate combinations of antibodies give consistent dose‐response patterns which may be used to identify and estimate amounts of cross‐reacting compounds. Previously reported methods of analyzing cross‐reaction patterns include multiple regression, principal components analysis and minimum estimates of variance (MEV). Four other techniques which are preferable in theory have been surveyed: discriminant analysis (DA), maximum likelihood estimates (MLE), classification and regression trees (CART), and computational neural networks (NN). MLE and simple back‐propagation neural networks can estimate the concentration, as well as the identity, of individual compounds. These four methods worked well with unfitted, unscaled data from monoclonal assays of triazines, phenylureas and avermectins. Immunoassays must be properly designed to provide adequate data for pattern recognition. Cross‐reactivity pattern analysis will make multi‐analyte, multi‐antibody immunoassays feasible for many applications in toxicology and hazard assessment.     

HnRNP CBP35-CBP67 interaction during stress response and ageing

Previous studies have demonstrated the existence of nuclear carbohydrate binding proteins in a variety of mammalian cells with molecular masses of 35 000, 67 000, and 70 000 (CBP35, CBP67, and CBP70), which are associated with nuclear ribonucleoprotein (RNP) complexes. CBP35 consists of two domains, an aminoterminal portion that is homologous to certain regions of proteins of the heterogeneous nuclear RNP complex, and a carboxyl-terminal portion homologous to β-galactoside-specific lectins. CBP35 it has been proposed, like the glucose-specific lectin, CBP67, to guide RNP complexes through the nuclear pore. Here we show that the exposure of mature rats to stress induces an increase in nuclear CBP35 bound to CBP67 and retained on immobilized glucose. Nuclear extracts from the livers of old rats displayed no detectable stress response. This CBP35·CBP67 association detected in rat liver is considered with respect to the CBP35·CBP70 association recently observed in HL60 cell nuclear extracts.     

A monoclonal antibody against a new differentiation antigen of thymocytes

B14-2-14 is a monoclonal cytotoxic IgM antibody which reacts with thymocytes of all mouse strains tested. The fraction of positive cells (by visual immunofluorescence) varies between strains from about 25-45% in A.CA to 65-85% in C57BL/6, and high levels are dominant in F1 hybrids. In the periphery, the antigen is found on a few percent of lymph node and not on splenic T cells, and it is absent in nude mice. Among thymocytes, the distribution of the B14 determinant largely overlaps with that of the TL antigen and of molecules binding peanut agglutinin. The B14 antibody reacts only minimally with hydrocortisone-resistant thymus cells. Biochemical analysis shows that B14 antibody, anti-TL antibody and peanut agglutinin bind to separate molecules. The target of the B14 antibody may be either an immature, thymic form of Thy-1, or another molecule associated with it. Two polypeptides, of 40 and 35 kDa are precipitated by both B14 and anti-Thy-1 antibodies from biosynthetically labeled thymus cell lysates, and two others, of 27 and 17 kDa, from surface-iodinated thymus cell preparations. B14-2-14 offers an additional method for identification and selection of thymocytes at different stages of differentiation, and should also be useful for studies of the Thy-1 antigen.     

T cell developmental defects in 'viable motheaten' mice deficient in SHP-1 protein-tyrosine phosphatase. Developmental defects are corrected in vitro in the presence of normal hematopoietic-origin stromal cells and in vivo by exogenous IL-7

Defects in the gene that encodes SHP-1 protein tyrosine phosphatase result in multiple hematopoietic abnormalities and generalized autoimmunity in viable motheaten (me(v)) mice. These mice also exhibit early thymic involution and abnormalities in T cell development. Here, we describe the use of fetal thymic organ culture (FTOC) and bone marrow adoptive transfer to study the effects of SHP-1 deficiency on thymocyte development. Chimeric FTOC established with normal bone marrow placed onto deoxyguanosine-treated fetal thymic lobes or onto scid fetal thymic lobes generated T cells. Bone marrow from SHP-1-deficient me(v)/ me(v) mice generated decreased numbers of T cells in chimeric FTOC established using deoxyguanosine-treated thymi but generated normal numbers in chimeric FTOC established using scid thymi. However, scid fetal thymi seeded with me(v)/ me(v) bone marrow also exhibited morphological abnormalities and contained elevated numbers of macrophages. Addition of IL-7 to me(v)/ me(v) bone marrow-seeded scid FTOC led to increased cell numbers, particularly of macrophages. Intrathymic injection of IL-7 partially restored the ability of progenitor cells in me(v)/ me(v) bone marrow to populate the thymus of adoptive recipients. We conclude that abnormal T cell development in me(v)/ me(v) mice may in part be due to defects in the ability of bone marrow-derived accessory cells to provide bioavailable IL-7 to developing thymocytes.     

Platelet aggregation and strenuous exercise

1. Platelet aggregation in the Chandler's tube has been found to be increased in a group of normal male and female volunteers who undertook strenuous physical exercise. This coincided with acceleration of the ;intrinsic' blood clotting system and a rise in fibrinogen. The rise in fibrinogen occurred despite increased fibrinolysis.2. The study confirms the sensitivity of the platelet aggregation system to changes in the ;intrinsic' clotting mechanism. Acceleration of this system in this study resulted from a physiological cause and produced accelerated aggregation in the coagulation-affected phase.     

Molecular epidemiology of Pseudomonas aeruginosa colonization in a burn unit: persistence of a multidrug-resistant clone and a silver sulfadiazine-resistant clone

To study the epidemiology of Pseudomonas aeruginosa colonization in a 32-bed burn wound center (BWC), 321 clinical and 45 environmental P. aeruginosa isolates were collected by prospective surveillance culture over a 1-year period and analyzed by serotyping, drug susceptibility testing, and amplified fragment length polymorphism (AFLP) analysis. Among 441 patients treated at the center, 70 (16%) were colonized with P. aeruginosa, including 12 (17%) patients who were colonized on admission and 58 (83%) patients who acquired the organism during their stay. Of the 48 distinct AFLP genotypes found, 21 were found exclusively in the environment, 15 were isolated from individual patients only, and 12 were responsible for the colonization of 57 patients, of which 2 were also isolated from the environment, but secondary to patient carriage. Polyclonal P. aeruginosa colonization with strains of two to four genotypes, often with different antibiotic susceptibility patterns, was observed in 19 patients (27%). Two predominant genotypes were responsible for recurrent outbreaks and the colonization of 42 patients (60% of all colonized patients). The strain with one of those genotypes appeared to be endemic to the BWC and developed multidrug resistance (MDR) at the end of the study period, whereas the strain with the other genotype was antibiotic susceptible but resistant to silver sulfadiazine (SSD(r)). The MDR strain was found at a higher frequency in sputum samples than the SSD(r) strain, which showed a higher prevalence in burn wound samples, suggesting that anatomic habitat selection was associated with adaptive resistance to antimicrobial drugs. Repeated and thorough surveys of the hospital environment failed to detect a primary reservoir for any of those genotypes. Cross-acquisition, resulting from insufficient compliance with infection control measures, was the major route of colonization in our BWC. In addition to the AFLP pattern and serotype, analysis of the nucleotide sequences of three (lipo)protein genes (oprI, oprL, and oprD) and the pyoverdine type revealed that all predominant strains except the SSD(r) strain belonged to recently identified clonal complexes. These successful clones are widespread in nature and therefore predominate in the patient population, in whom variants accumulate drug resistance mechanisms that allow their transmission and persistence in the BWC.     

Secretin and VIP-stimulated adenylate cyclase from rat heart

The exact positions of microelectrodes used to measure thePO₂ in the cerebral cortex of the rat were determined by staining the tissue with Alcian Blue. The measurement sites were subsequently located under a light microscope and correlated with the capillary and cellular arrangement of the cortex. The microelectrodes used for thePO₂ measurements were made of gold glass fibers; the Alcian Blue was injected hydrostatically through a micropipette attached to thePO₂ microelectrode. The sites where dye had been deposited were seen under a light microscope as green blue spots about 100 m in diameter. The capillaries were visualized by silver nitrate perfusion. Differences between the localPO₂ values in the neo- and the archeocortex were found. In the neocortex the meanPO₂ was 31 mm Hg, capillary volume 1.6%, capillary surface area 980/mm², capillary length 13.5/mm; whereas in the archeocortex these values where 21 mm Hg, 0.9%, 820/mm² and 9.4/mm respectively. These data indicate a relationship between the microcirculatory transport system and the local oxygen tension and provide further evidence that the meanPO₂ level tends to decrease when moving from the surface into the archeocortex.Supported by the Deutsche ForschungsgemeinschaftReported in part at the 3rd Symposium of ISOTT, Cambridge, GB, 1977; and at the 27th International Congress of Physiological Sciences, Paris, France, 1977