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R J Armitage

Publications and source records attributed to R J Armitage.

At least 91 records · Page 5Linked to original sources
PubMed1990

Regulation of interleukin 4 receptors on human T cells.

Human recombinant interleukin 4 (IL-4) was modified with biotin-N-hydroxysuccinimide and used to examine the expression of human IL-4 receptors (IL-4R) on activated peripheral blood T cells by flow cytometry. Freshly isolated T cells expressed only a low level of IL-4R which remained unchanged when cells were cultured in the absence of stimuli. In the presence of IL-4, IL-7, phytohemagglutinin A (PHA), or immobilized CD3 mAb the intensity of biotinylated IL-4 staining increased approximately 2-fold on the majority of cells. A combination of mitogen with either IL-4 or IL-7 caused an increase in receptor expression over that seen in the presence of mitogen alone. IL-2 alone failed to induce IL-4R, although it was able to induce a significant increase in receptor expression on T cells co-cultured with PHA or CD3 mAb. Flow cytometric analysis of purified T cell subsets confirmed that the up-regulation of IL-4R occurred on both CD4+ and CD8+ subpopulations. Two-color staining of T cells activated with PHA and IL-7 revealed that this increase in IL-4R expression occurred almost exclusively on cells expressing the p55 IL-2Ra subunit, although a significant number of cells expressing p55 do not express IL-4R. Analysis of IL-4R expression by this flow cytometric technique was substantiated by 125I-labeled IL-4 binding data and Northern blot analysis of IL-4R mRNA levels, suggesting that use of biotinylated human IL-4 for ligand binding and its detection by flow cytometry provides a very sensitive method for the study of IL-4R regulation.

Biotin↗
PubMed1989

Expression and functional role of CD23 on T cells.

We have found that approximately 10%-15% of tonsil, but not peripheral blood, T cells express the CD23 antigen following activation with 12-O-tetradecanoylphorbol 13-acetate (TPA), phytohemagglutinin (PHA) or recombinant interleukin 4. The proliferative response of tonsil T cells is significantly increased when CD23 monoclonal antibodies (mAb) are present in the cultures. In contrast, no such proliferative augmentation is seen when peripheral blood T cells are cultured in this way. Supernatant (SN) of Epstein-Barr Virus-transformed B lymphoblastoid cell lines (EBVLCL), is found to have a similar co-stimulatory effect on the proliferation of tonsil T cells to that seen with CD23 mAb. This effect is greatly diminished by preclearing SN with CD23 mAb. Similarly, SN from a CD23+ L cell transfectant augments the proliferative response of tonsil T cells to both TPA and PHA. The CD23 molecule expressed by TPA-driven T cell blasts appears identical in size to the 45-kDa glycoprotein present on EBVLCL and activated B cells. In contrast, a 42-kDa molecule is observed when CD23 is precipitated from T cells activated with PHA. The results presented here demonstrate that CD23 is expressed on activated tonsil, but not peripheral blood T cells and plays a role, via the binding of CD23 mAb and CD23+ material, present in EBVLCL and CD23+ transfectant SN, in the regulation of T cell proliferation in response to mitogens such as PHA and TPA.

Adjuvants, Immunologic↗
PubMed1989

Increased expression of surface IgM but not IgD or IgG on human B cells in response to IL-4.

Surface IgM (sIgM) was increased up to 10 times on human tonsillar B cells activated with IL-4. No change was observed for surface IgD, IgG or IgE. Other activators of human B cells, such as TPA, EBV and anti-IgM resulted in increased expression of the low-affinity receptor for IgE (CD23), but had no effect on sIgM. IL-4 also increased sIgM expression on prolymphocytic leukaemic (PLL) B cells, whereas TPA significantly reduced the level of sIgM. The effect on sIgM thus seems specific for IL-4, and is consistent with the existence of a unique IL-4-dependent B-cell activation pathway. Preincubation with IL-4 did not 'prime' B cells to proliferate in response to subsequent exposure to anti-IgM, and slightly decreased the response to co-stimulation with IL-4 and anti-IgM. The increase in sIgM expression in response to IL-4, therefore, does not seem to be important for proliferation.

B-Lymphocytes↗
PubMed1988

A new antigen identified by the monoclonal antibody UCHB 1 delivers a costimulatory signal to a subset of human B cells.

A novel anti-B cell monoclonal antibody UCHB1 is described which detects an antigen present on a selected subpopulation of both normal and leukemic B cells. Approximately 20% of normal tonsil and peripheral blood (PB) B cells are UCHB 1+ and the majority of B cells from all cases of prolymphocytic leukemia (PLL) tested, together with a low, variable percentage of PB B cells from non-Hodgkin's lymphoma patients with centroblastic centrocytic leukemia also express this antigen. Chronic lymphocytic leukemia and hairy cell leukemia B cells, pre-B acute lymphoblastic leukemia and Epstein-Barr virus transformed cell lines all lack UCHB 1 positivity as do all non-B lineage leukocytes and cell lines so far tested. In tonsil sections UCHB 1 staining is almost completely confined to surface IgM+ mantle zone lymphocytes and follicular dendritic cells, but not B cells, within the germinal centers. UCHB 1 can induce a rise in the level of intracellular free calcium ([Ca2+]i) in PLL B cells and low concentrations of monoclonal antibody can result in the entry of these cells into cell cycle in the absence of additional factors. The proliferative effect of UCHB 1 is greatly enhanced in the presence of Staphylococcus aureus Cowan and, to a lesser extent, phorbol ester. A similar costimulatory effect is exerted on a proportion of normal tonsil B cells although here, despite inducing a rise in [Ca2+]i, UCHB 1 alone does not cause cells to proliferate. UCHB 1 may well prove to be a useful antibody both to distinguish between different B cell leukemias and to study the phenotype and function of leukemic and normal B cell subpopulations.

Animals↗
PubMed1988

Functional interaction between B cell subpopulations defined by CD23 expression.

Using the CD23 monoclonal antibody (mAb) MHM6 and sheep anti-mouse Ig bound to magnetic beads we have obtained highly purified populations of MHM6+ and MHM6- tonsil B cells. We have found that the increased expression of MHM6 reactivity seen on B cells after activation results from up-regulation of antigen on cells already weakly positive and not from expression of new antigen on the previously negative population. The strong proliferative responses of MHM6+ cells seen in the presence of anti-IgM (alpha mu) and interleukin 4 (IL4) or the CDw40 mAb G28-5, and with Staphylococcus aureus Cowan I (SAC), and to a lesser extent with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA), resemble that seen among unfractionated B cells. In contrast, the MHM6- population cultured alone responds only weakly to alpha mu + G28-5 or SAC and exhibits virtually no response to alpha mu + IL4 or TPA. With all these mitogenic stimuli, tritiated thymidine uptake by the MHM6- population is augmented three- to sixfold by the addition of mitomycin C (MC)-treated MHM6+ cells. Pretreatment of cells with anti-leukocyte functional antigen 1 mAb has little effect on the subsequent proliferation of the MHM6- population but shows cell contact to be critical for the proliferation of MHM6+ cells. Such pretreatment has revealed that the functional interaction observed between MHM6+ and MHM6- cells is dependent on both cell contact and the presence of an MHM6+ cell-derived soluble component. We have found that addition of soluble CD23, purified from Epstein-Barr virus-transformed lymphoblastoid cell line supernatant, increases the proliferative response of MHM6- tonsil B cells to mitogenic stimuli in the presence of inactivated MHM6+ cells but has no effect on proliferation when MHM6+ cells are absent. By way of contrast to normal B lymphocytes, we have examined functional responses of prolymphocytic leukemia (PLL) B cells. Although these cells, when freshly isolated, show comparable levels of CD23 expression to normal B cells, this expression is not increased upon activation. In addition, in contrast to normal B cells, the PLL MHM6- population cultured alone shows a strong proliferative response to various mitogenic stimuli, comparable to that of MHM6+ or unfractionated cells, and this response is not augmented by the addition of MC-treated MHM6+ cells. Thus, a novel functional interaction is described between normal, but not leukemic, B cell populations defined by their expression of CD23.(ABSTRACT TRUNCATED AT 400 WORDS)

Antibodies, Monoclonal↗
PubMed1988

Characterization of two CD23 monoclonal antibodies with reactivity distinct from other antibodies within this cluster of differentiation.

We have produced two CD23 monoclonal antibodies (mAb), LA1 and LA2, which differ significantly in their patterns of reactivity compared to other mAb within this cluster. Unlike other CD23 mAb, LA1 and LA2 show virtually no reactivity with freshly isolated tonsil B lymphocytes or mantle zone lymphocytes in tissue section. That LA1 and LA2 are CD23 mAb is confirmed by their precipitation of a 45,000 MW surface protein from B cells and strong reactivity with a CD23 transfectant. Cross-blocking studies with four well-characterized CD23 mAb show that LA1 and LA2 recognize the same, distinct epitope of the CD23 molecule. However, similar to other CD23 mAb, expression of LA1 and LA2 increases after activation. Following removal of cells staining with the well-characterized CD23 mAb MHM6, using a highly efficient magnetic bead technique, LA1 and LA2, but not other CD23 mAb, react with a subpopulation of the remaining cells when activated with interleukin-4 (IL-4) or phorbol ester. Soluble LA1 and MHM6 both provide a co-stimulatory signal for phorbol ester-induced B-cell proliferation. This response is increased if these mAb are used to cross-link the CD23 molecule. Interestingly, despite the fact that LA2 and LA1 cross-block, LA2 has no effect on functional responses in its soluble form but can elicit a comparable increase in proliferation when cross-linked. Results presented here suggest that the novel CD23 mAb, LA1 and LA2, recognize a distinct form of the CD23 molecule, expressed only on activation. These mAb define a subpopulation of activated B cells which do not stain with other CD23 mAb.

Antibodies, Monoclonal↗
PubMed1986

Certain myeloid cells possess receptors for interleukin-2.

A proportion of blasts from five of 10 cases of AML expressed receptors for IL-2 (IL-2R) when tested directly ex-vivo with monoclonal antibodies against the receptor. After in-vitro stimulation with various agents including TPA, gamma interferon and colony stimulating factor, the purified blast cells of all cases of AML tested (10 of 10) showed high levels (50-90% cells positive) of IL-2R expression. Granulocytic cells from the promyelocyte stage onwards lacked IL-2R both before and after in-vitro stimulation. In contrast, leukaemic promonocytes and normal peripheral monocytes expressed IL-2R both before and after stimulation. The receptors were detected with two different monoclonal antibodies (anti-Tac and 4H3--both IgG 2a antibodies) by indirect rosetting. In selected experiments, results were confirmed by fluorescence microscopy and by the APAAP technique. Normal monocytes possessed only small amounts of IL-2R since positivity was clearly detectable only by the indirect rosette assay. Irrelevant IgG 2a first-layer and second-layer-only controls were always negative. The endogenous nature of the IL-2 receptors was demonstrated by re-expression after capping and shedding. That the antigens detected were true IL-2R was confirmed by the fact that monoclonal antibody staining was blocked by recombinant IL-2. The restricted expression of IL-2R on early granulocytic and on monocytoid cells raises the possibility that IL-2 is important in the proliferation of these cell types.

Antigens, Surface↗
PubMed1986

Lymphocyte function after autologous bone marrow transplantation (BMT): a comparison with patients treated with allogeneic BMT and with chemotherapy only.

T- and B-cell function after autologous bone marrow transplantation (ABMT) was assessed and compared with that found after allogeneic BMT and after chemotherapy only. In all 16 patients with acute leukaemia in remission treated with high-dose chemotherapy and single or double ABMT, T-helper numbers and function in an assay measuring PWM-induced Ig synthesis were grossly defective and closely resembled the defects observed after allo-BMT involving chemoradiotherapy (six patients). T-helper activity was more variable after chemotherapy only (eight patients), but in individual patients the defect was as great as that observed after BMT. In contrast, suppressor activity was comparably increased in all patient groups and increased numbers of Leu 15+ Dr+ Tac- suppressor T cells were consistently observed, suggesting chronic activation of suppressor T cells, the cause of which remains unknown. B-cell function was also uniformly impaired in all patients tested. It is therefore concluded that defective immune function after BMT is not due to alloimmune or radiotherapy-mediated effects. Furthermore, since many patients were studied a prolonged period after BMT and had no T cells with a thymic phenotype and no evidence of infection, it is unlikely that the defects are secondary to cellular immaturity following marrow regeneration or to superadded infection. The gross immune defects observed after various forms of BMT are likely, therefore, to be directly attributable to the chemotherapy involved.

Acute Disease↗
PubMed1986

Normal and certain leukaemic B cells express IL-2 receptors without in vitro activation.

IL-2 receptor expression by B cells has previously been considered to be confined to activated normal B cells and, among the B cell leukaemias, to the hairy cells (HC) of hairy-cell leukaemia. In the present paper, using alpha-Tac monoclonal antibodies in a highly sensitive indirect rosette method, we show that both normal and certain leukaemic B cells other than HC express IL-2 receptors. The density of these receptors is low since they were not detectable by indirect immunofluorescence. Various controls excluded non-specific-reagent or exogenous receptor binding and blocking studies with recombinant IL-2 confirmed the presence of the IL-2 receptors. The significance of the findings is discussed and it is suggested that B cell IL-2 receptor expression without in-vitro activation may be a function of B cell maturity.

Antibodies, Monoclonal↗
PubMed1985

Hairy-cell leukemia with hybrid B-T features: a study with a panel of monoclonal antibodies.

The peripheral blood of three patients with otherwise typical hairy-cell leukemia (HCL), but with a substantial number of circulating cells expressing both light chain restricted surface immunoglobulin (SIg) and sheep erythrocyte (E) receptor, was studied with a panel of monoclonal antibodies. The presence of hybrid B-T surface features was confirmed and, although as in previous studies of E+SIg+ proliferations, the precise phenotypes varied at different times of study, E+ non-T SIg+ and E+T+SIg+ populations were at times present in all three patients together with typical B hairy-cell (HC) and phenotypically normal T-cell populations. In one patient an E-OKT11+SIg+ population was also observed. Extensive precautions were taken to exclude spurious explanations for these hybrid phenotypes. These results are discussed in relation to the recent demonstration that both HCs and normal B cells can express T-cell features after appropriate in vitro stimulation.

Animals↗
PubMed1985

Bone marrow macrophages and megakaryocytes express common acute lymphoblastic leukaemia antigen.

Common acute lymphoblastic leukaemia antigen (CALLA) was demonstrated on a proportion of bone marrow macrophages and megakaryocytes. CALLA was detected by two monoclonal antibodies (J5 & BA3) in a three-layer immunoalkaline phosphatase system applied to routine air-dried bone marrow smears. The J5 staining was confirmed by an indirect immunofluorescent method and the CALLA was shown to be at the surface of the macrophages and megakaryocytes by an indirect immunogold technique. The findings are discussed in relation to the known tissue distribution of CALLA and to the clinical use of anti-CALLA antibodies for bone marrow purging.

Antibodies, Monoclonal↗
PubMed1983

A B-cell proliferation with aberrant true E-rosette formation: a sequential study with a panel of monoclonal antibodies and other surface markers.

A case of B-CLL in prolymphocytic transformation is described in which large numbers of peripheral blood mononuclear cells possess surface immunoglobulin and rosetted with AET-treated sheep erythrocytes (SIg+E+), but lacked specific T-cell antigens. The SIg (MDGK) was shown to be an intrinsic product of the cell, whose B-cell nature was confirmed by staining with BA1, a specific anti-B-cell monoclonal antibody. The E positivity resembled the rosetting of normal T cells in certain important respects but was weak, and aberrant in certain other respects. Although E rosetting was blocked with anti-chi and anti-D but not with anti-lambda, extensive blocking studies with a panel of monoclonal antibodies indicated that this was due to steric hindrance of weak E receptor rather than specific blocking of SIg possessing anti-E activity. The case is compared and contrasted with previous rare examples of SIg+E+ proliferations and briefly discussed in relation to the recent demonstration that certain non-T cells can express E receptor in vitro.

Aged↗
PubMed1982

The morphology and cytochemistry of human T-cell subpopulations defined by monoclonal antibodies and Fc receptors.

Leu 2a+ (suppressor/cytotoxic) and Leu 3a+ (helper/inducer) T-cell subsets of normal peripheral blood lymphocytes, purified by fluorescence-activated cell sorting, respectively showed 50 +/- 22% (range 31-92%) and 82 +/- 9% (range 69-93%) dot non-specific esterase (NSE) and 48 +/- 20% (range 31-91%) and 79 +/- 10% (range 64-92%) dot acid-phosphatase (APase) staining. Mature T cells defined by monoclonal antibody (UCHT1) displayed 81% and 79% dot NSE and APase positivity, while E-rosetting cells not staining with UCHT1 showed only 15% and 10% dot-positivity and were generally larger cells with more abundant cytoplasm. Examination of Fc-rosetting cells within the different T-cell subsets showed that dot positivity was not directly related to microFc receptor (microFcR) expression; particularly among Leu 2a+ lymphocytes, many microFcR+ cells lacked dot staining. It is concluded that dot staining for hydrolytic enzymes is a marker of true T-cells (as defined by monoclonal antibodies), although a minority of such cells (approximately 20%) lack this staining pattern. Although Leu 3a+ cells display a higher percentage of dot positivity than do Leu 2a+ cells, the difference is not clinically useful, and the two cell populations are not readily distinguishable on morphological grounds. The previously reported association between dot staining and microFc receptor expression is shown to be an indirect one, attributable to the fact that most T-cells, defined by monoclonal antisera, possess microFcR whereas most E+ UCHT1- cells lack microFcR.

Acid Phosphatase↗
PubMedDate not supplied

CD153.

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Amino Acid Sequence↗
PubMedDate not supplied

CD154.

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Amino Acid Sequence↗