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Biomedical subjects

G Pawelec

Publications and source records attributed to G Pawelec.

At least 127 records · Page 7Linked to original sources
PubMed1990

Involvement of CD45 in MHC class II-allospecific cytotoxicity.

Twenty-seven different CD45 monoclonal antibodies (mAb) were assessed for their ability to block cytotoxicity of alloreactive CD4+ MHC class II-specific or CD8+ class I-specific human T cell clones (n = 3 and 5, respectively). Twelve of 27 blocked the former but only 1/27 the latter, although all 27 significantly inhibited MHC-unrestricted lysis of K562 cells by either CD4+ or CD8+ clones. MAb pretreatment of effector cells but not target cells resulted in retention of blocking. Crosslinking the CD45 with goat anti-mouse Ig serum did not result in blockade of lysis by class I-specific clones or reveal blocking of class II-specific clones not inhibited by mAb alone. These results suggest that CD45 molecules may be predominantly involved in MHC class II-specific but not class I-specific allocytotoxicity as well as MHC-unrestricted natural killer-like cytotoxicity.

Antibodies, Monoclonal↗
PubMed1990

Expression of MHC class II epitopes on human T lymphocyte clones.

Twenty-four CD4+ alloreactive helper T cell clones and eight CD8+ cytotoxic T cell clones from five different donors, all of which were dependent on alloantigen and IL 2 for continued growth, were analyzed by FACS for cell surface expression of HLA-DR, -DQ, and -DP epitopes using monoclonal antibodies against monomorphic and polymorphic determinants. Clones were tested early (less than 30 population doublings) and late (greater than 45 population doublings) in their life-spans and at various times (3-5 days) after antigenic restimulation. All clones expressed high levels of HLA-DR at all times, and lower but significant levels of both HLA-DQ and -DP. In contrast, B lymphoblastoid cell lines expressed equivalent amounts of HLA-DR and -DQ, but less HLA-DP. There was no evidence of differential regulation or expression of the three major MHC class II isotypes on different T cell subsets, and neither did antibodies specific for polymorphic epitopes fail to react on clones from donors carrying the appropriate alleles.

Antibodies, Monoclonal↗
PubMed1990

Human T cell clones with gamma/delta and alpha/beta receptors are differently stimulated by monoclonal antibodies to CD2.

Requirements for stimulating autocrine proliferation of human T cell clones expressing either alpha/beta or gamma/delta antigen receptors via the "alternative" CD2 pathway have been examined using a large set of monoclonal antibodies (mAb). In the presence of autologous accessory cells (AC, B-lymphoblastoid cell lines) 2 of 13 single CD2 mAb (CLB-T11.1/1 and 6F10.3) stimulated proliferation of gamma/delta but not alpha/beta cells. Interleukin (IL) 1 or IL 6 did not substitute for AC in stimulating gamma/delta clones. Addition of CD28 mAb YTH 913.12 with the CD2 mAb did not result in stimulation of any alpha/beta clones. In the absence of AC, none of the CD2 mAb singly could stimulate any T cell clones, but pairs of mAb directed to different epitopes of CD2 (CLB-T11.1/1 + CLB- T11.2/1 or 6F10.3 + 39C1.5) stimulated both alpha/beta and gamma/delta clones. In both cases, stimulation was reduced by the presence of CD3 mAb. These results confirm that the established AC-independent alternative pathway of T cell activation, which requires binding of two separate epitopes of CD2, operates in both gamma/delta and alpha/beta T cells, and further suggest that an additional pathway initiated by binding of a single CD2 epitope in the presence of AC is exclusively operational in gamma/delta cells.

Antibodies, Monoclonal↗
PubMed1990

Cytokine regulation of the balance between alloindifferent and allospecific suppressor induction in mixed lymphocyte cultures.

The effects of exogenous cytokines on the generation of alloindifferent, MHC-unrestricted suppressive activity early on in mixed lymphocyte culture interactions have been investigated. Interleukin 4 strongly blocked the generation of suppression, whereas IL-1, IL-2, and IL-6 enhanced it to some extent. Tumor necrosis factor-alpha, interferons-alpha and -gamma, granulocyte/macrophage colony-stimulating factor, granulocyte CSF, IL-3 and IL-5, and a number of combinations of these factors were without effect in this system. Insofar as the alloindifferent suppression studied here also inhibited the development of allospecific, MHC restricted suppressive activity later in MLC, reduction by IL-4 of its development may have relevance for the use of this cytokine to facilitate the induction of specific suppressor cell-mediated transplantation tolerance in vivo.

Biological Factors↗
PubMed1990

Phenotypic and functional characterization of tumor infiltrating lymphocytes in mycosis fungoides: continuous growth of CD4+ CD45R+ T-cell clones with suppressor-inducer activity.

Tumor-infiltrating lymphocytes (TIL) were obtained by mechanical release from a solitary rapidly grown tumor of a patient with mycosis fungoides. The preparations separated by density gradient centrifugation contained a major portion of CD3+ CD8+ WT31+ CD5- large T-cell blasts and a minor portion of non-blastic TIL predominantly of the CD3+ CD4+ phenotype. Using cDNA-probes for the constant region of the T-cell receptor beta-genes, the large cell fraction was identified as tumor by its distinct monoclonal rearrangement. TIL were expanded by culture in recombinant interleukin 2 and cloned by limiting dilution. Phenotypic analysis of expanded TIL and two clones further analyzed in more detail showed CD3+, CD4+, CD8-, and 2H4+ (CD45R+) expression. Cloned and uncloned TIL showed no NK and LAK activity, no proliferative response, and no cytotoxic activity against autologous tumor cells. These cells were unable to suppress the proliferative response of alloreactive T-cell clones stimulated by B-lymphoblastoid cell lines (i.e., they had no suppressor-effector activity), but strongly suppressed proliferation responses in allogeneic mixed lymphocyte culture (i.e., they most likely had suppressor-inducer activity). This was not the case when irradiated tumor cells were added. The present results demonstrate continuous in vitro growth of CD4+ and 2H4+ T-cell clones with suppressor-inducer activity obtained from TIL, and indicate that a subpopulation of TIL may down-regulate immune responses which may lead to suppression of antitumor immunity.

Antigens, CD↗
PubMed1990

CD4+ CD45R- suppressor-inducer T-cell clones: requirements for cellular interaction, proliferation and lymphokines for the induction of suppression in peripheral blood mononuclear cells.

Regulation of the induction of suppressive activity in peripheral blood mononuclear cells (PBMC) by human major histocompatibility complex (MHC) class II+ CD4+ CD45R+ suppressor-inducer T-cell clones has been investigated. Previously, it was shown that in this system, cyclosporin A-sensitive precursors gave rise to allo-indifferent MHC-unrestricted CD4+ suppressive cells. Their induction could be blocked by monoclonal antibodies (mAb) to multilocus MHC class II gene products (TU 39) but not by mAb preferentially reacting with HLA-DR, -DQ or -DP molecules. This product, functionally defined, was termed 'DY'. It is shown here that induction of suppression by DY follows established activation pathways: (i) cell adhesion was required because CD11a (LFA-1) mAb blocked suppressor-induction; (ii) CD4 mAb also blocked, consistent with the involvement of class II products in suppressor-induction; (iii) cell proliferation was required because mAb to transferrin receptors, or irradiation, inhibited induction; and (iv) such proliferation appeared to be interleukin (IL)-2-dependent because it was blocked by mAb to IL-2 receptor, and enhanced by exogenous IL-2 but not IL-4. It was also enhanced by exogenous IL-1 and IL-6, but not by IL-3, tumour necrosis factor-alpha (TNF alpha) or interferon-gamma (IFN-gamma). It therefore seems that the requirements for activation of suppression by CD4+ DY+ T-cell clones in this in vitro model bear many similarities to those for CD4+ helper T cells, namely, mediation by MHC class II with CD4 involvement, dependency on LFA-1-influenced cell interactions, and reliance on clonal expansion caused by IL-2 and possibly amplified by IL-1 and/or IL-6.

CD4 Antigens↗
PubMed1990

Lymphokine release, suppressor cell generation, cell surface markers, and cytotoxic activity in cancer patients receiving natural interleukin-2.

We monitored patients treated for 5 days with continuous infusion of increasing doses (3 to 6 x 10(6) U/d) of natural interleukin-2 (IL-2). CD16+, CD25+, and CD56+ cells increased after treatment. Plasma tumor necrosis factor-alpha (TNF-alpha) levels, but not interferon-gamma (IFN-gamma) levels, increased during IL-2 treatment, but spontaneous and IL-2-stimulated TNF-alpha secretion in vitro remained abnormally low. However, mitogen-stimulated TNF-alpha release was normal. Mitogen-stimulated, but not IL-2-stimulated, IFN-gamma release was strongly depressed. Low spontaneous and IL-2-stimulated cytotoxicity on K562 or Daudi increased after treatment. Low suppressor cell generation also normalized after treatment. This appears to be the first reported study of immunologic monitoring of cancer patients treated with natural rather than recombinant IL-2.

Antigens, Differentiation↗
PubMed1989

[Transplantation of bone marrow from unrelated donors in chronic myeloid leukemia].

Bone marrow transplantations in four patients (aged 8-28 years, median 27 years) with chronic myeloid leukaemia (CML) were performed from unrelated donors who were HLA-identical and MLC-negative. One patient was in the stage of refractory blast crisis, one in a chronic phase, and two in the second chronic phase. Conditioning treatment consisted of fractionated radiation and administration of cyclophosphamide; in the patients with their second chronic phase additionally etoposide. Cyclosporin A and methotrexate were administered to prevent graft versus host reaction. The patient in the blast crisis died on day 12 after transplantation of Candida pneumonia. The other three patients are still alive 128, 306 and 530 days, respectively, after transplantation, only a mild form of graft versus host disease having occurred. It is suggested that for patients younger then 50 years with CML in the chronic phase an unrelated donor should be searched for in the absence of a familial donor.

Bone Marrow Transplantation↗
PubMed1989

Differential secretion of tumor necrosis factor-alpha and granulocyte/macrophage colony-stimulating factors but not interferon-gamma from CD4+ compared to CD8+ human T cell clones.

Tumor necrosis factor-alpha (TNF-alpha) is a pleiotropic lymphokine which may have important regulatory effects on immune responses. It is shown here that eight alloreactive CD4+ T cell clones (TCC) secreted significant amounts of TNF-alpha after stimulation with either specific alloantigen or 12-O-tetradecanoylphorbol 13-acetate together with the calcium ionophore ionomycin (up to 50 ng/ml/24 h/10(6) cells) whereas CD8+ TCC failed to do so (max. 2 ng/ml/24 h/10(6) cells). The CD8+ TCC also secreted markedly less granulocyte/macrophage colony-stimulating factor than the CD4+ cells. However, this was not indicative of a general decrease of lymphokine production by CD8+ cells because CD4+ and CD8+ TCC both secreted similar amounts of interferon-gamma. These results show that regulatory CD4+ lymphocytes can produce large amounts of TNF-alpha, whereas CD8+ effector cells cannot do so.

Clone Cells↗
PubMed1989

Antitumor activity in vitro in chronic myelogenous leukaemia revealed after treating peripheral cells with cytosine arabinoside.

Cytosine arabinoside (Ara-C) treatment of peripheral blood mononuclear cells from 12/12 chronic-phase chronic myelogenous leukaemia (CML) patients revealed a proliferative response stimulated by their untreated leukaemic cells. Specific recognition of tumour cells by patients' normal lymphocytes was suggested by the finding that cells of siblings genotypically identical for human leukocyte antigen caused no stimulation. Lymphocytes thus stimulated by tumour cells from one of these patients were cloned by limiting dilution and tested for antileukaemic effects in cytotoxicity and proliferation assays. Cytotoxic lines were isolated that killed autologous CML targets but only a limited number of allogeneic fresh leukaemias or cell lines. These results show that anti-leukaemia effectors can be isolated from chronic-phase CML patients and suggest their potential application in adoptive immunotherapy.

Antigens, Differentiation↗
PubMed1989

Partial correction of defective generation of lymphokine-activated killer cells in patients with chronic myelogenous leukaemia after in vivo treatment with interferon-alpha (Wellferon).

Patients with chronic myelogenous leukaemia (CML) in untreated chronic phase are deficient in their ability to generate lymphokine-activated killer (LAK) cells from peripheral blood mononuclear cells although they possess essentially normal levels of CD16+ and Leu19+ lymphocytes, which do not seem to be actively suppressed by tumour cells. Attempts to enhance LAK cell generation in these patients are reported here. Combining the lymphokines interleukins-2, with -4 and -5 (IL-2, IL-4, IL-5), was not successful; in fact, IL-4 depressed LAK cell induction in both normal donors and CML patients. The phorbol ester 12-O-tetradecanoylphorbol 13-acetate also failed to enhance cytotoxicity of normal donors or patients, and indomethacin was similarly without effect. The only agent found to enhance LAK cell induction by IL-2 in normal donors was interferon-gamma (but not IFN-alpha) and even this modest effect was not seen with the cells of CML patients. Increasing concentrations of IL-2 and/or culture duration also failed to improve LAK cell generation by patients. The only improvement in LAK cell generation was observed in CML patients treated for one or more months with IFN-alpha, where a steady increase of LAK activity with time after initiation of therapy was noted. These results show that the blockade of LAK cell induction in chronic-phase myelogenous leukemia patients is difficult to lift pharmacologically in vitro but possibly susceptible to biological response modifiers in vivo.

Cells, Cultured↗
PubMed1989

Selective inhibition of interleukin 2 but not of interferon-gamma, tumour necrosis factor-alpha or granulocyte/macrophage colony stimulating factor secretion by human helper T cell clones after antigen-driven tolerisation.

Alloreactive human T-helper cell clones chronically exposed to specific antigen can become tolerised, i.e. lose their autocrine proliferative capacity and no longer undergo antigen-driven clonal expansion. To study parameters of possible clonal anergy in such cells, lymphokine secretion before and after tolerisation was measured. 10/10 CD4+ clones were found to secrete interleukin 2 (IL-2), interferon gamma, tumour necrosis factor alpha and granulocyte/macrophages colony stimulating factors. Tolerised clones which had lost autocrine proliferative capacity and had lost the ability to secret IL-2 nevertheless retained the ability to secrete the other lymphokines. These results thus show a highly selective lesion in the noncoordinate regulation of lymphokine secretion by tolerised cells.

Cells, Cultured↗
PubMed1989

Regulation of normal myelopoiesis and chronic myelogenous leukaemia cell proliferation through a non-cytotoxic mechanism by a gamma/delta T cell clone.

Regulatory effects on myelopoiesis and myelogenous leukaemia cell proliferation mediated by a human T cell clone (TCC) carrying a gamma/delta receptor have been studied. MHC-unrestricted cytotoxicity could be induced in this clone by culture with IL-2 but not IL-4. Increasing concentrations of IL-2 resulted in increased lysis of natural killer (NK)-susceptible target cells but lysis of NK-resistant targets could not be induced. Moreover, cytotoxicity on fresh chronic myeloid leukaemia cells was not measurable even after culture with 1000 U/ml IL-2. However, NK-resistant targets could be lysed when anti-receptor antibodies (OKT3 or TCR-delta 1) were added to the assay. Clone 290-2 cells secreted lymphokines potentially inhibitory for myelopoiesis (TNF-alpha, IFN-gamma), and their supernatants could inhibit optimally stimulated granulocyte/macrophage colony formation by normal bone marrow. Moreover, 290-2 cells prevented the consistently observed IL-3-stimulated enhancement of proliferation of CML cells, although even IL-3-pretreated leukaemic cells were still resistant to lysis by this clone. Thus, cells of this type, even when not directly cytolytic, could have a role in the regulation of myeloid cell growth.

Antibodies, Monoclonal↗
PubMed1989

Involvement of "accessory" and antigen receptor molecules in human helper T cell clone activation studied by monoclonal antibody inhibition.

The requirements for activation of autocrine proliferation in human helper T cell clones (Th-TCC) by allogeneic cells were examined in monoclonal antibody (MoAb) blocking studies. Stimulation was not blocked by CD4, CD5, CD6, CD7, or CD45 MoAbs, despite high levels of expression of these antigens on the TCC. Only CD2 and CD11a (LFA-1) MoAbs blocked activation, the latter only when peripheral blood mononuclear cells (PBMCs) and not B-lymphoblastoid cell line (B-LCL) cells were used at stimulators. Responses to interleukin 2 (IL 2) were only minimally blocked by any of the MoAbs. All TCC were CD3+ and expressed the alpha/beta chain T cell receptor (TCR) as detected by moAb WT31. Accordingly, CD3 and WT31 MoAbs consistently blocked stimulation by B-LCL, and in addition one anti-DR5 TCC and one anti-DQw3 TCC were blocked by MoAb 42/1C1, which is directed to an idiotypic determinant of the HPB-ALL leukemic line TCR. Only these two TCC reacted with moAb 42/1C1 in flow cytometry. These observations suggest that CD2- but not LFA-1-mediated interactions, as well as TCR and stimulating antigen binding, are absolutely necessary to activate Th-TCC.

Antibodies, Monoclonal↗
PubMed1989

HLA-DP antigens in patients with chronic autoimmune thrombocytopenia (AITP).

AITP, a disease with well-defined autoimmune character, has been previously studied for a possible HLA association. However, no such association with antigens of the A, B, C or DR loci was found. As this does not exclude a possible association with HLA-DP antigens, we have investigated 36 patients with AITP for DP w1, w2, w3, w4 and w5 by primed lymphocyte typing using locally derived as well as the original DP reagents as used in the 9th International Histocompatibility Workshop. Comparison of antigen frequencies with those of 254 healthy controls revealed an increased frequency of DPw5 in the patient group which, however, was not statistically significant. Other discrepancies were not observed.

Adolescent↗
PubMed1989

Frequencies of HLA-DP alleles in the four major types of leukaemia.

The frequencies of HLA-DP alleles in 50 acute lymphocytic, 43 acute non-lymphocytic, 50 chronic myelogenous and 51 chronic lymphocytic leukaemia patients were compared with 254 controls using primed lymphocyte typing. In CLL and ANLL there were significantly decreased frequencies of DPw1. Decreased DPw1 and DPw3 was observed in ALL, but after correction for the number of comparisons made this was no longer significant. However, in ALL, even after correction, there were significantly increased frequencies of DPw2 and DPw5, whereas in ANLL and CLL the only significant increases were of DP-blank, and in CML there were no positive or negative associations at all. These results suggest an influence of DP alleles in disease susceptibility and resistance in three of the four major types of leukaemia.

Alleles↗