摘要:

SummaryThe continued proliferation of activated T cells requires the presence of a lymphocyte growth factor in the culture medium. This study describes a rapid, highly reproducible assay to quantitatively measure levels of this lymphokine. The use of Concanavalin‐A blast cells gives this assay a high degree of flexibility and convenience. It is shown that the lymphokine measured is Interleukin 2. The presence of an inhibitor in the supernatant of mitogen‐activated lymphocytes and the species specificity of the factor are demonstrated.

ISSN:0004-945X    

DOI:10.1038/icb.1980.55

出版商:Nature Publishing Group    

年代:1980

数据来源: WILEY

摘要:

SummaryThe lymphocyte costimulator (CoS) is a lymphokine required for the activation of T cell reponses to H‐2 alloantigens or mitogen. CoS activity is found in the supernatant medium of Concanavalin A (Con A) stimulated spleen cells. In this paper we investigate the cellular requirements for CoS production by Con A‐activated mouse spleen cells. Maximal lymphokine production in response to Con A depends on a co‐operative interaction between T cells and a nylon wool‐adherent cell present in the spleen of nude mice. T cells appear to be the major producers of CoS activity, doing so only in response to an initial inductive stimulus supplied by nude spleen cells. The inductive stimulus is found as a soluble factor in the supernatant of Con A‐activated spleen cells, and can also be provided by stimulatory (S+), but not by non‐stimulatory (S−), tumour cells H‐2 identical with the responding T cells. The activation of lymphokine‐producing T cells is thus a two‐signal process, requiring both mitogen and an additional inductive signal. Once activated, homogeneous populations of T cells will release lymphokine in response to mitogen alone.

ISSN:0004-945X    

DOI:10.1038/icb.1980.56

出版商:Nature Publishing Group    

年代:1980

数据来源: WILEY

摘要:

SummaryA study was undertaken into the binding of 7 fluorescein (FITC)‐labelled, lectins to sheep tissues and cells. Wheat germ agglutinin (WGA), conconavalin A (Con A) andRicinus communisagglutinin (RCA) bound strongly to all sheep tissues and circulating cells, whileDolichos biflorus(DBA) andUlex europaeus(UEA) did not bind at all. Peanut agglutinin (PNA) and soybean agglutinin (SBA) bound to thymus and lymph node cell suspensions and to a proportion of circulating cells, but only weakly to the other sheep tissues tested. PNA and SBA bound to polymorphs and monocytes, making it necessary to treat whole blood with carbonyl‐iron and a magnet to remove the phagocyctic cells before purification of the peripheral blood leucocytes (PBL).PNA bound to 40 to 50% of carbonyl‐iron treated PBL and to 65 to 70% of the cells in efferent popliteal lymph. Using a rhodamine‐labelled anti‐sheep Ig reagent>98% of PNA‐* cell in lymph and carbonyl‐iron treated PBL were sIg−Furthermore, using an FITC‐labelled F(ab)2anti‐sheep Ig reagent, the sum of the % PNA+cells and sIg+cells in individually labelled preparations was equal to She percentage of cells labelled when both reagents were added simultaneously. Cells binding PNA were found in more dense regions of buoyant density gradients and were less adherent to nylon wool than cells having surface immunoglobulin (sIg). Approximately 20 to 30% of PBL and 10 to 20% of the cells in lymph were PNA−/sIg−and these were termed ‘null’ cells.Although Con A induced sheep PBL to transform in tissue culture, PNA, SBA and WGA all failed to stimulate the incorporation of3H‐thymidine at the concentrations tested.Sorting lymph cells from BCG vaccinated sheep into PNA+and PNA−sub‐populations showed that the cells able to transformin vitroto the specific antigen, purified protein derivative (PPD) or the mitogen phytohemagglutinin (PHA) were in the PNA+but not PNA−population.

ISSN:0004-945X    

DOI:10.1038/icb.1980.57

出版商:Nature Publishing Group    

年代:1980

数据来源: WILEY

摘要:

SummaryTen sheep foetuses were thymectomized between 55 and 77 days gestation. The subsequent growth of the lambs was not affected for periods up to 500 days after birth. Prior to 240 days of age the thymectomized lambs were markedly lymphopenic and the response of their blood lymphocytes to phytohaemagglutinin (PHA) was significantly reduced. Peanut agglutinin‐binding cells were found to be depleted in the blood of thymectomized lambs, while an unmarked ‘null’ cell population was virtually absent. The absolute numbers of E‐rosette forming cells and sIg+cells were similar for both groups. These findings indicated that ‘null’ cells in sheep may be immature thymus‐dependent lymphocytes. The effects of thymectomy on blood lymphocyte counts, PHA responsiveness and the numbers of ‘null’ cells were less evident in thymectomized sheep that survived beyond 240 days. Possible differentiation pathways for sheep T‐cells are discussed, together with the role played by the thymus in the maturation of T‐cells.

ISSN:0004-945X    

DOI:10.1038/icb.1980.58

出版商:Nature Publishing Group    

年代:1980

数据来源: WILEY

摘要:

SummaryIn male rats exposed to cigarette smoke, antipyrine clearance was enhanced to the same extent as has been observed in human cigarette smokers. The activity of aryl hydrocarbon hydroxylase, a representative microsomal mixed function oxidase, was increased significantly in lung and kidney of smoke‐exposed rats compared with controls. The activity of this enzyme in the liver, however, was not altered by cigarette smoke. Although aryl hydrocarbon hydroxylase activity in extrahepatic tissues was significantly enhanced after cigarette smoke exposure, the total drug metabolizing capacity of these tissues remained trivial compared with that of the liver. Hence, extrahepatic drug metabolism is unlikely to account for enhanced antipyrine elimination in cigarette smokers. The present study has established an animal model for studying the changes produced by cigarette smoke which result in enhanced drug metabolism in man.

ISSN:0004-945X    

DOI:10.1038/icb.1980.59

出版商:Nature Publishing Group    

年代:1980

数据来源: WILEY

摘要:

SummaryThe juice of the banana trunk produces a non‐depolarising neuromuscular block. Oxygenation of the extract enhances its potency. Reversals with anticholin‐esterases are transient. Partial reversals in isolated preparations indicate these could be both specific and non‐specific binding which could account for blockade after washing. It could be specifically bound to ACh receptors in an irreversible way since its action appears similar to that of α‐Bu TX.

ISSN:0004-945X    

DOI:10.1038/icb.1980.60

出版商:Nature Publishing Group    

年代:1980

数据来源: WILEY

摘要:

SummaryAfter intradermal injection of 107promastigotes of a particular isolate of the intramacrophage protozoan parasite,Leishmania tropica, the development of disease (cutaneous lesions) is much more severe in BALB/c than in three other mouse strains, C57BL/6, C3H/He and CBA/H. Using fixed promastigotes and125I‐labelled protein A in a solid‐phase radioimmunoassay (RIA), titres of antibody were shown to increase up to about day 50 of infection. However, titres were not markedly different in BALB/c mice compared with the other three resistant strains, although antibody levels were highest in sera from the diseased BALB/c mice at late time points. Using isotype‐specific antisera in the RIA, and sera from the day 50 time point, the isotype distribution of anti‐promastigote antibodies was not noticeably different in sera from mice of the four genotypes with IgG1and IgG2a (IgG2b) antibodies predominating. It is concluded that differences in susceptibility to disease in this murine model of cutaneous leishmaniasis do not correlate with any decrease or increase in any particular antibody response to the promastigote.

ISSN:0004-945X    

DOI:10.1038/icb.1980.61

出版商:Nature Publishing Group    

年代:1980

数据来源: WILEY

ISSN:0004-945X    

DOI:10.1038/icb.1980.62

出版商:Nature Publishing Group    

年代:1980

数据来源: WILEY

摘要:

SummarySingle XO individuals ofRattus tunneyiandMesembriomys gouldii(Rodentia: Muridae) proved to be phenotypic females. Comparisons of the ovaries of these individuals with XX controls revealed that theR. tunneyiwas histologically normal, whereas theM. gouldiiwas histologically unusual. The results are discussed in relation to the Lyon and Hawker hypothesis which relates fertility of XO mammals to shortness of life‐span.

ISSN:0004-945X    

DOI:10.1038/icb.1980.63

出版商:Nature Publishing Group    

年代:1980

数据来源: WILEY

摘要:

SummaryThe laboratory mouse was evaluated as a model to assess the genetic stability of influenza A mutants of potential use as living vaccine strains. The growth of three mutant recombinants. A/Hong Kong/68‐ts‐IE (H3N2), A/HK/123/77x‐ts‐1A2 (H1N1) and A2/AA/6/60‐ca(H2N2) was studied in 15 g mice. Yields ofts‐1E from both lungs and turbinates were ten‐fold less than that of a control virus with the same surface antigens. Allts‐1E isolates showed evidence of loss oftsphenotype.Ts‐1A2 andcarecombinants grew to a much lower titre than those ofts‐1E, and revertants were obtained from onets‐1A2 lung isolate and onecaturbinate isolate. In other studies with hamsters, the stability of thetscharacter of these mutants during replication in the lungs of hamsters has been shown to be correlated with their residual virulence for man (Murphyet al., 1972; Murphyet al., 1974; Richmanet al., 1977). The results from the present study suggest that the laboratory mouse is at least as sensitive as the hamster as anin vitromodel for the detection oftsrevertants.

ISSN:0004-945X    

DOI:10.1038/icb.1980.64

出版商:Nature Publishing Group    

年代:1980

数据来源: WILEY