摘要:

AbstractRecombinant IL2, and immunosorbent/high performance liquid chromatography‐purified interleukin 2 (IL2) obtained from the human T cell leukemic line Jurkat, but not interferon‐α or ‐γ, were able to substitute for T cells in specific antibody responses to influenza virus by T cell‐depleted (E−) human peripheral blood mononuclear cells, and resulted in antibody formation equivalent to that obtained in the presence of T cells. The antibody response was shown to be antigen specific by using two non‐cross‐reacting strains of influenza virus (A/X31 and B/HK). IL2 in this assay therefore functions as a T cell‐replacing factor. Less than 1 % of T (UCHT1+) cells were present in the E−preparations, and this number did not increase during the 7‐day culture with antigen and IL2. Because the frequency of T helper cells for X31 is known to be less than 5 ± 10−5, this low number of contaminating cells excluded indirect action of IL2 through antigen‐specific T helper cells. Three to four times less IL2 was required for antibody production by E−cells than was needed for optimal proliferation by an IL2‐ dependent T cell line. Moreover, the concentration of anti‐Tac required for 50% inhibition of the IL 2‐induced antibody response was 50 times less than required for 50% inhibition of IL2‐dependent proliferation by the T cell line. But when T cells were added back to the E−cells, the anti‐Tac inhibition curve shifted back to that obtained with the T cell line. In cell labeling experiments, Leu11+cells but not HNK1+cells were increased in E−cells cultured with antigen and IL2. This increase in Leu 11+cells was abolished by prior passage of the E−cells through Sephadex G‐10 columns without affecting the IL2‐induced antibody response. From these experiments we conclude that IL2 can replace T cells in specific antibody responses, and that the IL 2 effect is not mediated indirect

ISSN:0014-2980    

DOI:10.1002/eji.1830160902

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractHuman peripheral blood mononuclear cells (PBMC) were tested for the expression of Fee‐receptor (FcεR) after stimulation with various mitogens in the absence of IgE. FcεR were found on virtually all the cells from 19 Epstein‐Barr virus‐transformed B cell lines including those derived from cord blood, from one agamma‐globulinemic patient and VDS‐0 pre‐B cells. Hence, the data clearly indicate that FcεR may be expressed on very immature B cells. PBMC cultures stimulated with either pokeweed mitogen (PWM), phytohemagglutinin (PHA) or concanavalin A displayed an early increase of their content in FcεR‐bearing cells followed by a decrease to levels below those of the control cultures. After fractionation of the PWM‐stimulated cultures into T and B cell‐enriched preparations, most of the FcεR+cells were in the B cell fractions and the same low levels of FceR+cells were found in the T cell fractions isolated from the PWM‐stimulated and from the control cultures. Double‐labeling experiments, employing biotinylated F(ab')2monoclonal antibody to FcR and either fluorescein isothiocyanate‐conjugated B1 or Mo2 monoclonal antibodies, indicated that PWM mainly exerted its effect on B cells and on monocytes. This effect was T cell dependent and it was mediated by soluble factors of T cell origin. At the peak of the PHA or concanavalin A response, most of the FceR‐bearing cells were found in the B cell fraction but the T cells isolated from mitogen‐stimulated cultures contained significantly more FcεR+cells than those from the control cultures, suggesting that T cell mitogens had increased the expression of FcεR on some T cells. This view was supported by the finding of a higher proportion of FceR+cells in PHA‐stimulated than in control cultures of highly purified T cells with a maximum response at the end of the culture period. Double‐labeling experiments at the peak (day 2) of the peripheral blood mononuclear cell response indicated that the expression of FcεR was increased on B cells (Bl+) and on monocytes (Mo2+). By using the same approach at the peak of the T cell response (day 7), it was found that T cells isolated from PHA‐stimulated cultures expressed more FcεR than those isolated from control cultures. Moreover, in unstimulated cultures, FcεR was mainly expressed on T helper cells (Leu 3+) whereas in PHA‐stimulated cultures FcεR was expressed on both T he

ISSN:0014-2980    

DOI:10.1002/eji.1830160903

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractIn oxidation‐dependent cytotoxicity (ODCC), cytolytic T lymphocytes (CTL) non‐specifically recognize, bind to and lyse oxidized target cells (O‐TC) but the precise mechanism whereby CTL react with O‐TC is far from clear (Berke, G.,Immunol. Rev.1983.72: 5). Here we present evidence that CTL/O‐TC interactions are blocked by aldehyde‐reactive reagents such as hydroxylamine, adipic acid dihydrazide and thiocarbohydrazide and that preformed CTL/O‐TC conjugates dissociate upon reduction with NaBH4, suggesting that active aldehyde groups of O‐TC rather than intercellular Schiff bases are involved in the recognition and lysis of O‐TC by CTL in ODCC. The aldehydes are bound to trypsin‐sensitive, non‐H‐2 glycoproteins that appear to be different and unique in the three different target cell lines so far examined (EL4, L1210, R1.1). In view of these and previous findings we would like to suggest that in ODCC, active aldehydes react with adjacent major histocompatibility complex and perhaps other cell‐surface molecules to create a multitude of modified conformations, responsible for the “polyclonal” (nonspecific) MHC recognition and lysis of O‐TC by CTL, as well as for an altered pattern

ISSN:0014-2980    

DOI:10.1002/eji.1830160904

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractA systematic study has been conducted of the priming effect in the immunization against cholera toxin (CT). We demonstrate that a priming phenomenon can be achieved by synthetic peptides of the CT B subunit, leading (after a subsequent booster with a subimmunizing dose of the intact toxin) to an efficient anti‐CT neutralizing antibody response. This effect is obtained even upon a single administration of a peptide conjugate and even by peptides that as such are not able to induce CT cross‐reactive antibodies whatsoever. This effect is specific and dose dependent. A macromolecular carrier as well as an adjuvant are essential for the induction of antitoxin response. In this respect, a totally synthetic priming agent, CTP3‐poly (DL‐alanyl)–poly(L‐lysine), was adequate for an effective priming response. The specificity of the antibodies formed after the booster was mainly towards the whole CT molecule and only a small fraction of them were specific towards the peptide used for priming. The ability of synthetic peptides to prime the immune system towards a secondary stimulus with whole organism or native protein might be of general practical value, especially in endemic areas where the population is probably constantly exposed to a low level of a particular infectious agent. This exposure, which has no influence on the unprimed immune system, could serve as a booster in the case of individuals primed with an appropriate peptide, leading to a secondary immu

ISSN:0014-2980    

DOI:10.1002/eji.1830160905

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractA large collection of monoclonal antibodies (mAb) directed against sheep red blood cell (SRBC) receptor (cluster of differentiation 2 : CD2) were classified according to three criteria: (a) their inhibitory effect on T cell‐SRBC rosette formation; (b) the epitopic cluster recognized on the CD2 molecule; (c) their reactivity with resting or activated T cells. All mAb were then tested in a two by two checkerboard fashion for possible T cell mitogenicity, in presence or absence of a submitogenic dose of 12‐O‐tetra‐decanoylphorbol 13‐acetate (TPA), an agent known to be comitogenic for T cells, presumably in delivering a second signal, usually accessory cell dependent. The combined data demonstrate that in the absence of TPA only few pairs of mAb directed at distinct epitopes of the CD2 molecule were mitogenic for T cells (in approximately 30% of the population tested), and in the presence of a submitogenic dose of TPA the majority of T11.1 anti‐CD2‐mAb (9 out of 11) were strongly mitogenic for T cells of all individuals tested when paired with T11.2 anti‐CD2 mAb. The two anti‐T11.1 mAb, noncomplementary to anti‐T11.2 mAb, were, however, strongly mitogenic when added to mAb of the T11.3 subgroup, represented by 1‐Mono‐2A6.Taken together, these data strongly suggest that the main characteristic of T cell mitogenesis triggered by anti‐CD2 mAb is the requirement for a signal delivered simultaneously to two different epitopes of the CD2 molecule, whether these epitopes

ISSN:0014-2980    

DOI:10.1002/eji.1830160906

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractC3b receptor activity and decay‐accelerating activity for the C3 convertase, C3b, Bb, were demonstrated on rabbit erythrocytes (erab). Particles bearing C3b agglutinated ERABif the C3b was of rabbit origin, but not if it was of human origin. The reactivity of rabbit C3b was abolished by enzymatic conversion of C3b to C3bi. Deposited on ERAB. rabbit C3b, but not human C3b, was cleaved by factor I in the absence of factor H. Similarly, decay acceleration of the C3b, Bb complex on ERABoccurred when the complex was of rabbit origin, but not when it was of human origin. Soluble immune complexes in the presence of rabbit serum were bound to and then released from the erab. Binding of the complexes is presumed to be mediated by immune complex‐bound C3b and release to be the consequence of degradation of C3b by Factor I. These findings suggest that ERAB, like human erythrocytes, are endowed with membrane‐associated complement regulators that protect these cells against homologous complement attack and participate in the clearing mechanism of circulating immune comp

ISSN:0014-2980    

DOI:10.1002/eji.1830160907

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractCD23, p45 (BLAST‐2, EBVCS) is a 45‐kDa lineage‐restricted antigen which appears on the surface of human B cells shortly after activation. A monoclonal antibody (MHM6) to CD23, p45, as well as a polyclonal rabbit antibody raised against the purified antigen were found to promote DNA synthesis in purified tonsillar B cells which had been activated with phorbol ester. Interleukin 1, which was not, by itself, stimulatory for either resting or activated B cells, significantly augmented the growth‐promoting properties of MHM6. Kinetic studies indicated that while MHM6 exerted its influence in early G1, interleukin 1 acted later in the cycle just prior to the entry of cells into S phase. The findings demonstrate a role for CD23, p45 in triggering the progression of activated B lymphocytes through the G1phase of the cell cycle. The possibility that this antigen serves as a receptor for a B cell stimulatory factor is di

ISSN:0014-2980    

DOI:10.1002/eji.1830160908

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractIn C57BL/6 mice, cytotoxic T lymphocyte (CTL) lines have previously been found to exhibit low (<150 U/mg) or undetectable (<20 U/mg) adenosine deaminase (ADA) levels (Minkowski, Castellazzi and Buttin,J. Immunol.1984.133: 52) in contrast to what has been seen in T helper lines (1770 ± 340 U/mg; Minkowski and Bandeira,Cell. Immunol.1985.95: 380). Treatment of one of these CTL ADA−lines with the demethylating agent 5‐azacytidine gave rise to an ADA+population. Subsequent cloning allowed the recovery of pure ADA+clones showing a rather narrow range of activity with an average value of 2030 ± 504 U/mg. The restored ADA+activity is stable over several months of continuous growth. It is identical to the activity of C57BL/6 thymic cells or C57BL/6 T tumor lines regarding (a) its sensitivity to ADA inhibitors 2‐deoxycoformycin and erythro‐9‐(2‐hydroxyl‐3‐nonyl)adenine, and (b) its electrophoretic mobility under nondenaturing conditions (starch gel and isoelectric focusing). An ADA‐specific, 1.4‐kb mRNA is present in the reactivated clones but is undetectable in the CTL ADA−parental line. These results demonstrate that the ADA−phenotype is due to an extinction of the corresponding gene. They suggest that the extinction of the ADA gene which appears to be specific for CTL and to take placein vivoduring T cell differenciation may result from increased methylation in or near the ADA gene. This extinction seems to affect specifically ADA since nucleoside phosphorylase, the enzyme which follows ADA in the purine salvage pathway, is present at equivalent levels in t

ISSN:0014-2980    

DOI:10.1002/eji.1830160909

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractA subpopulation of interleukin 2 (IL 2) receptor‐positive day 14–15 murine fetal thymocytes can be induced by recombinant IL 2 to proliferate over prolonged time periods in dissociated cell cultures. The proliferating day 14–15 fetal thymocytes exhibit no cytolytic effector function, nor do they rearrange T cell receptor β chain genes. This contrasts with thymic organ cultures in which day 14–15 thymocytes do rearrange β chain genes and give rise to immunocompetent cells. However, such events can also take place in dissociated cell cultures, provided the IL 2‐responsive thymocytes are cultured on syngeneic feeder cells in the presence of IL 2 and the mitogen concanavalin A. Under such conditions rearrangement of the β chain gene complex becomes detectable and cytolytic effector cells are generated. The frequency of inducible cytolytic precursor cells in day 14–15 thymocytes is 1/7000. These data either imply that immunocompetent cells are already present in the day 14–15 fetal thymus, or differentiation from precursors to immunocompetent cells must occur in dissociat

ISSN:0014-2980    

DOI:10.1002/eji.1830160910

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractThe effect of a protease inhibitor, leupeptin, on the presentation of hen egg lysozyme (HEL) to cloned T cells was investigated. We found that leupeptin‐sensitive thiol proteases are apparently less involved when HEL is presented by the I‐Admolecule, than when it is presented by the I‐Edmolecule. This selectivity was more of a function of the antigen than that of the Ia molecule because presentation of denatured or fragmented HEL was not sensitive to leupeptin whereas antigen presentation to a number of I‐A‐restricted T cell clones specific to other antigens was sensitive to leupeptin. These data demonstrate that the particular combination of major histocompatibility complex/nominal antigen recognized by a certain T cell clone may require processing of the antigen molecule through a certain group of proteases and that other combinations are independent of that particular processing pathway. Furthermore, there is a preference for a certain type of processing depending on the Ia molecule

ISSN:0014-2980    

DOI:10.1002/eji.1830160911

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY