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N K Damle

Publications and source records attributed to N K Damle.

At least 37 records · Page 2Linked to original sources
PubMed1991

Binding of the B cell activation antigen B7 to CD28 costimulates T cell proliferation and interleukin 2 mRNA accumulation.

A successful immune response requires intercellular contact between T and B lymphocytes. We recently showed that CD28, a T cell surface protein that regulates an activation pathway, could mediate intercellular adhesion with activated B cells by interaction with the B7 antigen. Here we show that CD28 is the primary receptor for B7 on activated peripheral blood T cells, that CD28 binds to B7 in the absence of other accessory molecules, and that interaction between CD28 and B7 is costimulatory for T cell activation. To characterize the binding of CD28 to B7, we have produced genetic fusions of the extracellular portions of B7 and CD28, and immunoglobulin (Ig) C gamma 1 chains. 125I-labeled B7 Ig bound to CD28-transfected Chinese hamster ovary (CHO) cells, and to immobilized CD28 Ig with a Kd approximately 200 nM. B7 Ig also inhibited CD28-mediated cellular adhesion. The function of CD28-B7 interactions during T cell activation was investigated with soluble fusion proteins and with B7-transfected CHO cells. Immobilized B7 Ig and B7+ CHO cells costimulated T cell proliferation. Stimulation of T cells with B7+ CHO cells also specifically increased levels of interleukin 2 transcripts. These results demonstrate that the CD28 signaling pathway could be activated by B7, resulting in increased T cell cytokine production and T cell proliferation. Cellular interactions mediated by B7 and CD28 may represent an important component of the functional interactions between T and B lymphoid cells.

Animals↗
PubMed1991

Direct helper T cell-induced B cell differentiation involves interaction between T cell antigen CD28 and B cell activation antigen B7.

Cognate interactions between major histocompatibility complex class II antigen (Ag)-reactive CD4+ T helper (Th) and Ag-presenting B cells induce first the activation of B cells and their subsequent differentiation into Ig-secreting cells (IgSC). The Th cell-associated homodimeric glycoprotein CD28 has been implicated as an important regulator of Th activation. Recently, B cell-associated early activation Ag B7 has been identified as a ligand for the CD28 molecule. In this study, we have examined using monoclonal antibodies (mAb) the roles of CD28 and B7 molecules during the Th-B cell cognate interactions leading to the differentiation of B7+ B cells. Anti-CD28 mAb 9.3 specifically inhibited proliferative responses of CD4+ T cells to both allogeneic B cells and soluble Ag-presenting autologous non-T cells. In addition, anti-CD28 mAb 9.3 inhibited Th-induced differentiation of alloantigen-presenting B cells into ISC. Similar inhibition of both Ag-induced Th activation and B cell differentiation into ISC was observed using mAb BB1 which recognizes a B cell-associated molecule B7. In contrast, non-cognate Th-independent exogenous interleukin 6-induced differentiation of B7+ B cells into ISC was not inhibited by mAb to either molecule. These results clearly demonstrate the involvement of CD28 on Th and its ligand B7 on B cells during cognate Th-B interactions leading to the differentiation of B cells. Furthermore, these results also suggest the development of new mAb-based therapeutic approaches for exaggerated B cell activation associated with certain autoimmune diseases such as systemic lupus erythematosus.

Antigens, CD↗
PubMed1991

Direct interaction with primed CD4+ CD45R0+ memory T lymphocytes induces expression of endothelial leukocyte adhesion molecule-1 and vascular cell adhesion molecule-1 on the surface of vascular endothelial cells.

The process of recruitment of leukocytes at sites of inflammation involves direct cell-to-cell interactions between leukocytes and vascular endothelial cells (EC) mediated by various adhesion receptors on leukocytes and their inducible endothelial ligands. In this study we have examined the induction on EC of endothelial leukocyte adhesion molecule-1 (ELAM-1), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) upon their interaction with subpopulations of human T cells. When co-cultured with EC both resting CD4+ T and CD8+ T cells caused a modest increase in the expression of endothelial ICAM-1. Moreover, resting CD4+ but not CD8+ T cells induced expression of ELAM-1 and VCAM-1 on a small fraction of unstimulated EC. Prior activation with phorbol 12-myristate 13-acetate (PMA) significantly increased the ability of T cells to up-regulate endothelial ICAM-1 and also induced the expression of both ELAM-1 and VCAM-1. PMA-primed CD4+ T cells induced both VCAM-1 and ELAM-1 on EC more efficiently than CD8+ T cells. Furthermore, the ability to induce the expression of ELAM-1 and VCAM-1 was confined to the CD4+ CD45R0+ memory/primed subpopulation of T cells. This induction of various endothelial adhesion ligands could also be mediated by antigen-primed CD4+ T cell lines. The CD4+ T cell-mediated induction of adhesion ligands required direct intercellular contact with EC because neither cultures of EC and PMA-primed CD4+ T cells separated by a microporous membrane insert nor the conditioned medium of PMA-primed T cells induced expression of ELAM-1 and VCAM-1 on EC. Cyclosporin A significantly inhibited the activation of T cells with PMA but had no effect on the ability of PMA-primed T cells to up-regulate endothelial CAM. Thus, CD4+CD45R0+ T cells via as yet unknown mechanism can significantly enhance the expression of each of the three endothelial adhesion ligands and, thereby, may facilitate the process of recruitment of additional leukocytes to exacerbate inflammation.

Antigens, CD↗
PubMed1990

Ability of human T lymphocytes to adhere to vascular endothelial cells and to augment endothelial permeability to macromolecules is linked to their state of post-thymic maturation.

The accumulation of mononuclear cells at sites of chronic inflammation is dependent on a number of factors including localized adherence of lymphocytes to vascular endothelial cells (EC), cytokine-mediated increased adhesiveness of endothelium, chemotactic factors and endothelial permeability. The present study investigates two of the above attributes of lymphocyte-EC interaction: namely, the ability of maturationally distinct subpopulations of human T lymphocytes to adhere to vascular EC and to increase vascular endothelial permeability to macromolecules in an in vitro model. Thus, human T lymphocytes were separated into CD4+ CD8-helper/inducer, CD4- CD8+ cytotoxic/suppressor, CD29+ CD45RA- CD45RO+ memory, and CD29- CD45RA+ CD45RO- naive/virgin T subpopulations, were activated with PHA and PMA, and then examined for their adherence to EC and also for their effect on endothelial permeability. Upon activation, cells within each of the above four subpopulations exhibited increased adherence to EC. In contrast, resting CD29+ CD45RA- CD45RO+ memory T lymphocytes exhibited two to three times greater ability to adhere to EC than their CD29- CD45RA+ CD45RO- naive/virgin counterparts. Consistent with their increased adherence to EC, CD29+ CD45RO+ memory T lymphocytes, when activated, significantly increased endothelial permeability to albumin. Although activated CD45RA+ naive T lymphocytes exhibited increased adherence to EC, these cells failed to increase significantly endothelial permeability. Similar to their polyclonal counterparts, Ag-specific CD4+ CD29+ CD45RO+ T cell clones, but not their actively released mediators, also increased endothelial permeability via a noncytolytic mechanism(s). This ability of CD29+ CD45RO+ memory T lymphocytes to augment endothelial permeability may facilitate their transendothelial migration into extravascular space. These observations may provide additional insights into molecular mechanism(s) underlying pathophysiology of localized chronic inflammatory responses in general and more specifically selective accumulation of CD29+/CD45RO+ memory T lymphocytes at sites of chronic inflammation such as rheumatoid synovium.

Antigens, CD↗
PubMed1990

Stimulation of cloned human T lymphocytes via the CD3 or CD28 molecules induces enhancement in vascular endothelial permeability to macromolecules with participation of type-1 and type-2 intercellular adhesion pathways.

Perivascular accumulation of CD29+CD45R0+ memory T lymphocytes at sites of chronic inflammation such as rheumatoid synovium is commonly associated with the localized increase in the endothelial permeability. We have recently demonstrated that a direct interaction between activated CD29+CD45R0+ memory T lymphocytes and vascular endothelial cells (EC) results in the increased permeability of EC. In this report, we have investigated effects on antigen-specific T cell receptor (TcR) alpha/beta+ human T lymphocyte clones on the endothelial permeability to albumin. Our results show that CD29+CD45R0+ cloned human T lymphocytes augment endothelial permeability by a noncytolytic process requiring surface contact between T lymphocytes and EC. Both cytolytic and noncytolytic cloned T lymphocytes were capable of augmenting endothelial permeability and this process did not involve active lysis of EC. Stimulation of T lymphocytes via the CD3/TcR or CD28 molecules resulted in significant enhancement in the ability of T lymphocytes to influence endothelial permeability. Pretreatment of T lymphocytes with monoclonal antibodies directed at either CD11a/CD18 (LFA-1) or CD2 molecules or that of EC with monoclonal antibodies directed at either CD54 (ICAM-1) or CD58 (LFA-3) molecules significantly inhibited T lymphocyte-induced enhancement in endothelial permeability, thus indicating that activated T lymphocytes utilize both type-1 (CD11a/CD18CD54) and type-2 (CD2CD58) intercellular adhesion pathways to augment endothelial permeability and signals received via CD3 or CD28 molecules on T lymphocytes further enhance this process. Furthermore, proinflammatory cytokines interleukin 1 and tumor necrosis factor but not proinflammatory cytokines interleukin 1 and tumor necrosis factor but not interleukin 6 induced resistance in EC to T lymphocyte-mediated effects on their permeability. Collectively, these observations may provide insights into molecular mechanism(s) underlying pathophysiology of localized chronic inflammatory responses in general and more specifically selective accumulation of chronically activated memory T lymphocytes at sites of chronic inflammation.

Antigens, Differentiation↗
PubMed1990

CD45 ligation in T cells regulates signal transduction through both the interleukin-2 receptor and the CD3/Ti T-cell receptor complex.

The cytoplasmic domain of the CD45 leukocyte cell surface antigen has recently been shown to possess protein tyrosine phosphatase (PTPase) activity. The existence of a cell membrane-bound PTPase may represent a mechanism by which an activation signal, initiated by ligand binding to a surface receptor, is down-regulated following delivery of the signal. Both the interleukin-2 (IL2) growth factor receptor and the CD3/Ti T-cell antigen receptor contain a subunit which is phosphorylated on tyrosine by an activated protein kinase (PTK) during T-cell activation. We compared the effect of CD45 ligation on signal transduction mediated by the binding of IL2 or anti-CD3 to these two receptors. Immunoblotting with anti-phosphotyrosine antiserum was used to investigate the effect of CD45 ligation on anti-CD3- or IL2-induced protein tyrosine phosphorylation. When CD3 and CD45 were triggered together, changes in the pattern of tyrosine phosphorylation of specific substrates was observed in comparison to the stimulus triggered through CD3 alone. In contrast, CD45 ligation did not alter the pattern of tyrosine-phosphorylated proteins in "resting" T-cell blasts responding to IL2, except for a mobility shift of a 55 kDa protein and increased phosphorylation of a 112 kDa substrate. The proliferative response of T cells to both anti-CD3 or IL2 was inhibited by ligating CD45. The CD45 molecule down-regulated CD3-induced T-cell activation when the CD45 and CD3 molecules were ligated simultaneously with immobilized antibodies. In contrast, immobilized CD45 mAb alone inhibited IL2-induced proliferation, and the inhibition was not potentiated by simultaneously using a CD25 mAb which was non-competitive for IL2-binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1989

Stimulation via the CD3 and CD28 molecules induces responsiveness to IL-4 in CD4+CD29+CD45R- memory T lymphocytes.

Although both IL-2 and IL-4 can promote the growth of activated T cells, IL-4 appears to selectively promote the growth of those helper/inducer and cytolytic T cells which have been activated via their CD3/TCR complex. The present study examines the participation of CD28 and certain other T cell-surface molecules in inducing T cell responsiveness to IL-4. Purified small high density T cells were cultured in the absence of accessory cells with various soluble anti-human T cell mAb with or without soluble anti-CD3 mAb and their responsiveness to IL-4 was studied. None of the soluble anti-T cell mAb alone was able to induce T cell proliferation in response to IL-4. A combination of soluble anti-CD3 with anti-CD28 mAb but not with mAb directed at the CD2, CD5, CD7, CD11a/CD18, or class I MHC molecules induced T cell proliferation in response to IL-4. Anti-CD2 and anti-CD5 mAb enhanced and anti-CD18 mAb inhibited this anti-CD3 + anti-CD28 mAb-induced T cell response to IL-4. In addition, anti-CD2 in combination with anti-CD3 and anti-CD28 mAb induced modest levels of T cell proliferation even in the absence of exogenous cytokines. IL-1, IL-6, and TNF were each unable to replace either anti-CD3 or anti-CD28 mAb in the induction of T cell responsiveness to IL-4, but both IL-1 and TNF enhanced this response. The anti-CD3 + anti-CD28 mAb-induced response to IL-4 was exhibited only by cells within the CD4+CD29+CD45R- memory T subpopulation, and not by CD8+ or CD4+CD45R+ naive T cells. When individually cross-linked with goat anti-mouse IgG antibody immobilized on plastic surface, only anti-CD3 and anti-CD28 mAb were able to induce T cell proliferation. These results indicate that the CD3 and CD28 molecules play a crucial role in inducing T cell responsiveness to IL-4 and that the CD2, CD5, and CD11a/CD18 molecules influence this process.

Adjuvants, Immunologic↗
PubMed1989

IL-2-activated human killer lymphocytes but not their secreted products mediate increase in albumin flux across cultured endothelial monolayers. Implications for vascular leak syndrome.

When cultured with IL-2, human lymphoid cells acquire the ability to lyse various NK-resistant tumor targets. Due to their anti-tumor cytolytic effect, clinical trials with IL-2 alone or IL-2 + IL-2-activated killer (IAK) lymphocytes have been undertaken. However, infusion of therapeutically effective doses of IL-2 is associated with the development of systemic toxicity characterized by exaggerated endothelial permeability, also known as vascular leak syndrome. The present study was designed to examine the effects of IAK cells and their secreted products on vascular endothelial permeability by using an in vitro endothelial permeability model in which the flux of FITC-albumin across endothelial cell (EC) monolayers was measured. When endothelial monolayers were exposed to IAK cells for 2 h, significant increases in the transendothelial permeability to albumin were observed. Exposure of EC to lymphocytes cultured in the absence of IL-2 did not induce significant alteration in the endothelial permeability. In addition, neither culture supernatants of IAK cells nor purified recombinant cytokines, including IL-1 beta, IL-2, IL-3, IL-4, IL-6, TNF-alpha, GM-CSF, M-CSF, and IFN-gamma, had any effect on endothelial permeability in this model. Prior activation of EC with TNF-alpha did not alter the increased permeability induced by IAK cells or lack of it by nonactivated lymphocytes. Dexamethasone treatment of IAK cells abolished their anti-tumor cytolytic effect but only partially inhibited their ability to induce increased endothelial permeability. Pretreatment of IAK cells with mAb directed at the CD11a/CD18 (LFA-1) adhesion complex, and that of EC with mAb directed at the ICAM-1 molecule, inhibited the IAK cell-induced increase in endothelial permeability. These results demonstrate that direct cell-to-cell contact between IAK cells and EC is necessary and sufficient to cause increased endothelial permeability in this model system, and may therefore be an important factor contributing to the development of the vascular leak syndrome observed clinically.

Antibodies, Monoclonal↗
PubMed1989

Antigen-specific suppressor T lymphocytes in man.

The cellular signals that lead to activation of suppressor T cells (Ts) as opposed to cytotoxic T cells (CTL) are unknown. This review describes an in vitro suppressor-induction system developed by us to characterize interactions among various T cells leading to the development of antigen-specific suppression. In this system, antigen-specific CD4+ inducer T cells are first activated with antigen-presenting cells (APC). Antigen-primed CD4+ inducer blasts are then cultured with fresh autologous CD8+ T cells in the absence of the priming antigen. CD8+ T cells isolated from this culture suppress the proliferative response of autologous CD4+ T cells to the priming antigen only. The activated CD8+ Ts lyse neither APC nor antigen-primed CD4+ inducer T cells and can be distinguished from their CD8+CD28+ CTL counterpart by their lack of expression of the CD28 molecule. Furthermore, the ability to induce CD8+ Ts is restricted to antigen-primed CD4+CD29+CD45R-p80+ (Leu8+) T cells. Antibody-mediated inhibition experiments suggest the involvement of CD3/TCR and class I MHC molecules on the surface of CD4+ inducer T cells and the CD2, CD3/TCR, CD8, and CD11a/CD18 molecules on the surface of CD8+ Ts during both the induction and the effector phase of Ts function. Furthermore, compatibility at the class I MHC genes between CD8+ Ts and CD4+ antigen-reactive T cells is required for effective suppression of CD4+ T cells. Together, these results suggest that human antigen-specific CD8+ Ts employ the TCR complex to recognize TCR and class I MHC molecules on the surface of autologous CD4+ inducer T cells during the induction and effector phases of Ts function, and the apparent antigen specificity of suppression reflects specificity for antigen receptors on CD4+ antigen-reactive T cells. This may be a common mechanism by which antigen-specific suppression is accomplished.

Antigens↗
PubMed1989

Distinct regulatory effects of IL-4 and TNF-alpha during CD3-dependent and CD3-independent initiation of human T-cell activation.

The present study examines the effects of IL-4 and TNF-alpha on the CD3-dependent (Ag/MHC-initiated or anti-CD3 mAb-initiated) and CD3-independent (IL-2-initiated) pathways of the initiation of human T-cell activation. Both IL-4 and TNF-alpha significantly augmented the CD3-dependent T-cell proliferation induced by either irradiated OKT3 hybridoma cells or allogeneic B cells. In contrast, the CD3-independent IL-2-initiated T-cell proliferation was enhanced by TNF-alpha and significantly inhibited by IL-4. Although the growth-enhancing effects of both IL-4 and TNF-alpha on the CD3-dependent T-cell proliferation were noticeable regardless of when these cytokines were introduced in culture, the inhibitory effect of IL-4 on the CD3-independent IL-2-initiated T-cell activation was observed only if IL-4 was added at the initiation but not later than 24 hr of "T cells + IL-2" cultures. The growth-enhancing effects of both IL-4 and TNF-alpha on the CD3-dependent T-cell activation were not confined to any one subset of T cells. On the other hand, IL-4 inhibited the IL-2-induced proliferation of CD4+ (helper/inducer) T cells and CD45R+ (virgin) T cells but not that of CD8+ (cytotoxic/suppressor) T cells and CD45R (memory) T cells. When examined for their effects on cytokine production, CD3-dependent production of IL-2 and IFN-gamma was affected by neither cytokine, whereas IL-4 strongly inhibited the production of IFN-gamma by IL-2-stimulated T cells. Consistent with their enhancing and inhibitory effects, respectively, on IL-2-induced T-cell proliferation, TNF-alpha augmented and IL-4 inhibited the development of IL-2-stimulated MHC-unrestricted cytolytic (MUC) T-cell activity directed against tumor cells. When deprived of IL-2, MUC T cells rapidly lose their cytolytic activity, and despite its inhibitory effect on the development of MUC T cells, exposure of IL-2-deprived MUC T cells with decaying cytolytic activity to IL-4 retards the decay in their cytolytic activity. These results suggest the differential regulatory effects of IL-4 and TNF-alpha during human T-cell activation.

Antibodies, Monoclonal↗
PubMed1988

Differential regulatory signals delivered by antibody binding to the CD28 (Tp44) molecule during the activation of human T lymphocytes.

Molecule CD28 (Tp44) is expressed on the surface of majority of human T cells and has been implicated to play an active role in the regulation of T cell growth. The present study examines the effect of antibody binding to the CD28 molecule during T cell activation. Anti-CD28 but not isotype-matched anti-CD5 mAb consistently augmented anti-CD3-induced and IL-2-induced T cell proliferation and subsequent release of soluble CD25 molecule. When added together, mAb anti-CD28 and anti-CD5 acted synergistically to cause 2- to 7-fold enhancement of T cell activation induced by anti-CD3 mAb or IL-2 with no effect on the development of non-MHC-restricted IL-2-activated killer T cells. In contrast, alloantigen-induced T cell proliferation, soluble CD25 release, and the subsequent development of CTL were all inhibited by anti-CD28 mAb. Moreover, alloantigen-induced proliferative response of both CD4+ and CD8+ T cells was inhibited by anti-CD28 without affecting the cytolytic effect of CTL. Because valency of anti-CD28 binding has been implicated as an important factor in signal transduction, this was explored in the allogeneic MLR by using Fab and F(ab')2 fragments of anti-CD28 mAb and anti-mouse kappa mAb. The inhibitory effect of anti-CD28 mAb in the MLR was reversed by cross-linking of anti-CD28 mAb with anti-mouse kappa mAb. In addition, cross-linking of the CD28 molecule on alloactivated T lymphoblasts but not that on resting T cells with anti-CD28 and anti-mouse kappa induced their proliferation in the absence of the priming alloantigen. These results indicate that stimulatory or inhibitory signals delivered through the CD28 molecule are determined by the degree of cross-linking of this molecule. In addition, these results also suggest that Ag-induced CD3-TCR-mediated T cell responses are more dependent on signals delivered through the CD28 molecule than those induced with anti-CD3, and thus these results have implications for potential use of anti-CD28 in sustained propagation of Ag-specific T cells.

Antibodies, Anti-Idiotypic↗
PubMed1987

Interleukin-2 activated human killer lymphocytes: lack of involvement of interferon in the development of IL-2-activated killer lymphocytes.

When cultured with native or recombinant interleukin-2 (IL-2) human small agranular lymphocytes acquire the ability to kill various tumor targets. The development of these IL-2 activated killer (IAK) cells, also known as LAK, is observed in the absence of antigen or mitogen. Interferons are known to augment the lytic effects of natural killer cells and cytolytic T lymphocytes. Our study was undertaken to examine the effect of human alpha, beta, and gamma interferons on the induction and the effector phase of IAK function. When cultured with small lymphoid cells IFN alone did not induce anti-tumor cytolytic activity in those lymphocytes. Despite their known anti-proliferative effects, none of the 3 IFN species at any concentrations tested inhibited the development of IAK activity when present during the entire culture period. IFN neither inhibited nor augmented the development of IAK cells under suboptimal conditions. Furthermore, activation of IAK cells was not affected by the presence of neutralizing antibodies to either alpha or gamma IFN. Post-activation exposure of IAK cells to IFN also failed to either augment or inhibit their lytic activity. Thus, neither endogenously generated nor exogenously added IFN had any effect on the IAK system, in contrast to their augmenting effects on NK cells and CTL.

Cell Adhesion↗
PubMed1987

Immunoregulatory T lymphocytes in man. Soluble antigen-specific suppressor-inducer T lymphocytes are derived from the CD4+CD45R-p80+ subpopulation.

Regulation of the immune response in man is largely dependent on interactions between cells of the cluster designation 4+ (CD4+) helper/inducer sublineage and the CD8+ suppressor/cytotoxic sublineage. When cultured with autologous antigen-primed CD4+ lymphocytes, CD8+ cells differentiate into suppressor T cells (Ts) that specifically inhibit the response of fresh autologous CD4+ cells to the priming antigen only. The current study was undertaken to analyze the roles in this suppressor circuit of subpopulations of the CD4+ sublineage distinguished from one another on the basis of their binding (or lack of binding) to monoclonal antibodies against molecules p80 (Leu8) and CD45R (p220/Leu18/2H4). When examined for the proliferative responses to alloantigenic stimuli, each of the four: CD4+p80+, CD4+p80-, CD4+CD45R+, and CD4+CD45R- populations proliferated vigorously, synthesized interleukin 2 (IL-2) and interferon and released soluble IL-2 receptors. However, the responses to soluble antigens such as Candida and diphtheria toxoid were exhibited by CD4+CD45R-, CD4+p80+, and CD4+p80- cells, but not by CD4+CD45R+ cells. When examined for their ability to induced CD8+ Ts in the Candida-driven suppressor-induction culture system, only CD4+p80+ and CD4+CD45R- cells induced strong suppression. Further, when CD4+CD45R- cells were separated into CD4+CD45R-p80+ and CD4+CD45R-p80- subpopulations, despite the ability of both subpopulations to respond to Candida, only CD4+CD45R-p80+ cells induced autologous CD8+ Ts. Activated CD8+ Ts suppressed not only proliferation but also the release of soluble IL-2 receptors by autologous antigen-activated CD4+ cells. Thus, the antigen-specific suppressor-inducer T cells appear to be derived from the CD4+CD45R-p80+ (Leu3+, Leu8+, 2H4-) subpopulation of the CD4+ sublineage.

Antibodies, Monoclonal↗
PubMed1987

Interleukin 2-activated human lymphocytes exhibit enhanced adhesion to normal vascular endothelial cells and cause their lysis.

When cultured with native or recombinant interleukin 2 (IL 2), human lymphoid cells proliferate and acquire the ability to lyse both NK-sensitive and NK-resistant tumor targets. Such IL 2-activated killer (IAK) cells generally do not destroy nonmalignant nontransformed cells. Due to their apparent specificity for tumor cells, adoptive immunotherapeutic trials of IAK cells and IL 2 have been initiated, with promising results. However, infusion of high doses of IL 2 causes systemic toxicity in patients and experimental animals resulting in the development of a vascular leakage syndrome. Certain aspects of such toxicity suggest IL 2-induced, cell-mediated destruction of normal tissue. This study examines the interaction between IL 2-induced human lymphoid cells and endothelial cells (EC). IL 2, in a dose-dependent manner, causes lymphocytes to strongly adhere to EC, but not to tumor cells, fibroblasts, or epithelial cells. In addition, these IL 2-activated lymphocytes were highly cytotoxic not only to NK-resistant Daudi cells but also to vascular and corneal EC. The IAK cells caused lysis of not only human EC but also bovine EC. Although IAK cells did not display significant adherence to normal human fibroblasts or epithelial cells, when brought together by 50 X G centrifugation, these targets were lysed by IAK cells. The ability to lyse EC was not confined to any single subpopulation of IL 2-activated lymphocytes. The lysis of EC was mediated by both IL 2-activated large granular lymphocytes and small agranular lymphocytes. Furthermore, cells within both CD4+ and CD8+ sublineages of T cells, and also non-T subpopulations, mediated IL 2-induced cytolysis of EC. The destruction of EC by IAK cells may contribute in part to the systemic toxicity associated with infusions of high doses of IL 2.

Animals↗
PubMed1986

Interleukin 2-activated human killer cells are derived from phenotypically heterogeneous precursors.

When cultured with native or recombinant human interleukin 2 (IL 2), human peripheral blood non-adherent mononuclear cells (NAMNC) acquire the ability to lyse both NK-sensitive and NK-resistant tumor target cells. The development of these IL 2-activated killer (IAK) cells, also known as LAK, is observed in the absence of exogenous antigen or mitogen. This study describes the ability of various subpopulations of human peripheral blood NAMNC with defined surface phenotype to generate the IAK activity. Human NAMNC were separated into various subpopulations on the basis of the ability to bind monoclonal antibodies, activated with IL 2, and were examined for the cytolytic effect on various tumor target cells. Although CD16+ (Leu-11+) NK cells from NAMNC could become IAK cells when cultured with IL 2, removal of these cells from NAMNC had no effect on the latter's ability to generate the IAK effect. When CD16- NAMNC were separated into CD2+ E rosette-forming T cells (ERFC) and CD2- non-T (non-ERFC) subpopulations, both subpopulations generated the IAK activity. The ability of monoclonal antibody-defined subpopulations of T and non-T cells to generate IAK cells was then examined. Both CD4+ and CD8+ subsets isolated by either positive or negative selection generated the IAK activity. Similarly, CD20+ (B1+) B cells and CD20- non-T (null) cells developed into IAK cells when cultured with IL 2. In contrast, Leu-7+ T cells failed to generate the IAK activity. CD4+ and CD8+ subsets were additionally separated into narrower subpopulations by using monoclonal antibodies anti-Leu-8 and 9.3 respectively, and were examined for their ability to generate IAK cells. Precursors of IAK cells were derived from each of the four: CD4+, Leu-8+ (inducer), CD4+, Leu-8- (helper/amplifier), CD8+, 9.3+ (cytolytic), and CD8+, 9.3- (suppressor) subpopulations of T cells. Thus, the IAK activity appears to be derived from phenotypically heterogeneous and otherwise functionally diverse human lymphoid cells and is not confined to any single subpopulation.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1986

Generation of antigen receptor-specific suppressor T cell clones in man.

We have shown previously that CD8+ T cells proliferate upon exposure to autologous, antigen primed CD4+ T cells, and suppress the response of fresh T cells to the priming antigen but not irrelevant antigens. The stimulus and target of suppression in this system appears to be the antigen receptor on the surface of CD4+ cells, rather than the nominal antigen. In the current study, alloantigen primed CD4+ inducer cells and IL-2-containing medium were used to generate clones of suppressor cells from several individuals. The clones inhibited the response of fresh autologous T cells only to the original allogeneic stimulator cell and to stimulator cells that shared HLA-DR antigens with the priming cell. The clones were also genetically restricted, since they inhibited the response of HLA-A,B-compatible but not HLA-A,B-incompatible individuals. The availability of a method for reproducibly generating antigen receptor-specific suppressor T cell clones in vitro should make it possible to clarify the mechanism, whereby such cells are activated and exert their suppressive effect.

Clone Cells↗