The interleukin-2/interleukin-2 receptor system: structural, immunological, and clinical features.

Interleukin-2 (IL-2) has been the first and more extensively studied cytokine, in particular for its central role in the mechanisms of cell growth and differentiation. The function of IL-2 is mediated through specific receptors (IL-2R) present on the membrane of reacting cells. Using hybridoma and recombinant DNA technologies, both IL-2 and IL-2R have been biochemically characterized and purified and are available for in vitro and in vivo studies.

Prognostic significance of the evaluation of bronchoalveolar lavage cell populations in patients with HIV-1 infection and pulmonary involvement.

To investigate the prognostic utility of the morphologic and immunologic evaluation of BAL cell populations in determining mortality risk, we analyzed BAL data obtained from 115 patients infected with HIV-1. Forty fatal outcomes occurred within 73 patients with OI. The OI patients who died showed a significant increase in neutrophils with respect to surviving patients.

Different mechanisms of activation of proliferating CD3+ cells in patients with lymphoproliferative disease of granular lymphocytes.

To investigate the role of p55 and p75 chains of interleukin-2 receptor (IL-2R) on the activation of granular lymphocytes (GL) in patients with lymphoproliferative disease of granular lymphocytes (LDGL), the cells obtained from 11 LDGL patients (belonging to the CD3+ group) were studied for (a) the surface expression and (b) mRNA transcripts of the p55 and p75 IL-2R after activation with anti-CD3 monoclonal antibody (mAb) or interleukin-2 (IL-2). The effects of mAbs specifically blocking the p55 and p75 IL-2R on the generation of proliferative and cytotoxic functions were studied following anti-CD3 mAb stimulation. A significant difference was observed in the expression of p55 and p75 antigens on LDGL cells under resting conditions: a low number of p55 IL-2R+ (mean 1.

Clonally expanded CD3+, CD4-, CD8- cells bearing the alpha/beta or the gamma/delta T-cell receptor in patients with the lymphoproliferative disease of granular lymphocytes.

Among 60 retrospectively assessed patients with the lymphoproliferative disease of granular lymphocytes (LDGL), lymphocytes from only 2 patients had the CD3+, CD4-, CD8- phenotype, rarely observed in normal peripheral blood lymphocytes (about 3%). In this paper we report a detailed study of lymphocytes isolated from these two patients. The cells from patients 1 had the CD3+, CD4-, CD8-, WT31-, beta F1-, TCR delta 1+, Ti gamma A-, BB3+, CD7+, CD16-, CD57+ phenotype, while cells from patient 2 had a phenotype even more rarely observed on normal lymphocytes: CD3+, CD4-, CD8-, WT31+, beta F1+, TCR delta 1-, CD7+, CD16-, CD57+.

Alveolar macrophages from patients with AIDS and AIDS-related complex constitutively synthesize and release tumor necrosis factor alpha.

To verify the hypothesis that alveolar macrophages (AMs) from patients infected with HIV-1 could synthesize and release TNF alpha, AMs recovered from the BAL fluid of 11 patients with seropositive HIV-1 (six with AIDS and five with ARC) were tested in vitro for their ability to destroy TNF alpha-susceptible targets. Furthermore, the presence of TNF alpha was assessed in AM-conditioned supernatants on the basis of their cytotoxic activity and by using an immunoenzymatic test and immunoblotting. Transcription of the TNF alpha gene in AMs was also studied by means of the Northern blot analysis.

Shedding of the soluble form of the CD8 complex by CD8+/HLA-DR+ cells in HIV-1-infected patients.

High levels of the soluble form of the CD8 molecule (sCD8) are detectable in the serum of HIV-1-infected patients. To investigate the mechanisms accountable for the release of this molecule we evaluated the presence of sCD8 in the supernatants obtained from in vitro cultures of highly purified CD8 cells isolated from 20 HIV-1-infected patients. At resting conditions cultured CD8 cells from HIV-1-infected patients released low amounts of sCD8; no statistically significant differences were observed between unstimulated cultures from HIV-1-seropositive patients and from HIV-1-seronegative subjects at risk for HIV-1 infection or normal healthy controls.

Hepatitis B virus binds to peripheral blood mononuclear cells via the pre S1 protein.

The hepatitis B virus has been documented in hepatic and extrahepatic compartments, including bone marrow and peripheral blood cells. The viral protein involved in the attachment to human hepatocytes has been identified within the N-terminus of the pre S1 envelope protein. Using recombinant particles containing the pre S1, pre S2 and S encoded sequences, we studied which virus envelope protein is involved in binding to peripheral blood cells.

Tumor necrosis factor-alpha and B-cell growth factor induce leukemic hairy cells to proliferate in vitro.

To clarify the mechanisms accounting for the hairy cell proliferation, in five patients with hairy cell leukemia (HCL), we evaluated the ability of neoplastic cells to proliferate in vitro in response to tumor necrosis factor-alpha (TNF-alpha), B-cell growth factor (BCGF), and interleukin 4 (IL-4). In addition, supernatants recovered from cultures of unstimulated hairy cells were tested for the capability to induce the proliferation of allogeneic hairy cells. We demonstrated that TNF-alpha and BCGF were able to induce the in vitro growth of hairy cells (stimulation index (SI) ranging, at different concentrations, from 1.

Cell membrane expression and functional role of the p75 subunit of interleukin-2 receptor in lymphoproliferative disease of granular lymphocytes.

The cell membrane expression and functional role of the interleukin-2 receptor (IL-2R) was analyzed in nine patients with lymphoproliferative disease of granular lymphocytes (LDGL) using monoclonal antibodies (MoAbs) specific for the p75 (TU27) and the p55 (anti-Tac) subunits of IL-2R. Four patients were characterized by the proliferation of CD3+CD8+ granular lymphocytes (GL) expressing the alpha/beta T-cell receptor (T alpha beta) and one case by the proliferation of CD3+CD4-CD8- GL expressing the gamma/delta T-cell receptor (T gamma delta); in four additional cases proliferating cells were CD3 negative GL. Consistent with data observed on normal GL, phenotypic analysis demonstrated that patients' GL lack the expression of the p55 IL-2R, whereas the p75 subunit is constitutionally expressed by expanding GL of both T-cell (either T alpha beta and T gamma delta) and natural killer (NK) origin in variable proportions (11% to 94% of cells).

Mechanisms accounting for lymphocytic alveolitis in hypersensitivity pneumonitis.

Hypersensitivity pneumonitis (HP) is a lung disorder characterized by an exaggerated accumulation of CD8+ T lymphocytes in the pulmonary parenchyma. To investigate the mechanisms accounting for the T cell alveolitis taking place in the lung of HP patients and their pattern of growth, cells recovered from the bronchoalveolar lavage (BAL) of seven patients were evaluated for: 1) the expression of activation markers, including IL-2R (p55 and p75 subunits), HLA-DR and VLA-1 Ag; 2) the ability of IL-2 and IL-4 to induce in vitro proliferation; 3) the capability to synthesize and release IL-2 by determining the levels of IL-2 in BAL cell-free supernatants and by evaluating the presence of mRNA transcripts for IL-2; and 4) the molecular configuration of the beta- and gamma-genes of the TCR. This study demonstrates that a high number of BAL lymphocytes recovered from the lungs of HP patients express activation markers including the p75 chain of IL-2R, VLA-1, and HLA-DR Ag.

Cytotoxic events taking place in the lung of patients with HIV-1 infection. Evidence of an intrinsic defect of the major histocompatibility complex-unrestricted killing partially restored by the incubation with rIL-2.

To characterize the cytotoxic events taking place in the lung of patients with HIV-1 infection, we studied the cells recovered from the bronchoalveolar lavage (BAL) of nine patients with AIDS, seven patients with AIDS-related complex, and two patients with lymphadenopathy. Phenotypic analysis was coupled to a series of functional evaluations of nonspecific cytotoxic abilities performed on lung effectors, including their property to bind K-562 targets, to release natural killer cytotoxic factor (NKCF), and to become cytotoxic following in vitro activation with rIL-2. Our results demonstrated that lung cells bearing the NK-related CD16, CD56, and CD57 antigens were quantitatively increased, irrespective of the disease stage.

Mechanisms accounting for the defective natural killer activity in patients with hairy cell leukemia.

Natural killer (NK) cell activity is severely impaired in untreated patients with hairy cell leukemia (HCL). In an attempt to investigate whether this impairment is related to a defect at the target cell binding and/or at the post target cell binding level, we evaluated the peripheral blood mononuclear cells (PBMC) of HCL patients for their ability to: (1) bind and kill K-562 NK-sensitive targets at the single cell binding level; (2) release the NK cytotoxic factor (NKCF) under different in vitro stimuli, including K-562 and phytohemoagglutinin; and (3) kill K-562 targets in a lectin-dependent cellular cytoxicity (LDCC) assay. This study demonstrates that untreated HCL patients' PBMC show a low ability to form conjugates with K-562 targets at the single cell binding level (5.

Susceptibility to lysis of pulmonary alveolar macrophages by human lymphokine-activated killer cells.

In this study we addressed the question of whether lymphokine-activated killer (LAK) cells, besides killing neoplastic cells, may exert a certain degree of lysis on the normal counterpart; in particular we took into consideration the toxicity against pulmonary alveolar macrophages (PAM). We demonstrated that human LAK cells generated in vitro following incubation of peripheral blood mononuclear cells with recombinant interleukin 2 for 4 days were able to lyse normal PAM in a 4-h 51Cr release assay. Similarly, PAM recovered from patients suffering from nonneoplastic interstitial lung disorders, i.

Evaluation of serum levels of soluble interleukin-2 receptor in patients with chronic lymphoproliferative disorders of T-lymphocytes.

Serum levels of soluble interleukin-2 receptor (sIL-2R) have been evaluated in 33 patients with chronic lymphoproliferative disorders of T-lymphocytes, including 12 T-helper phenotype chronic lymphocytic leukemias (Th-CLL) and 21 lymphoproliferative diseases of granular lymphocytes (LDGL). All Th-CLL cases were negative for antibodies against type I human T-leukemia virus (HTLV-I). Serum levels of sIL-2R were significantly increased in patients with Th-CLL with respect to controls (P less than 0.

Serum levels of soluble CD8 are increased in patients with B chronic lymphocytic leukemia.

Serum levels of the soluble form of the CD8 (s-CD8) antigen were evaluated in the peripheral blood of 44 patients with B-CLL, using an enzyme-linked immunosorbent assay, and were correlated with clinical features and relevant hematological and immunological data. Increased values were observed with respect to normal age-matched controls (mean +/- S.E.

Lymphoproliferative disease of granular lymphocytes in a patient with concomitant hepatitis B virus infection of CD4 lymphocytes.

In this report we studied a 35-year-old male who developed an abnormal expansion of granular lymphocytes (GL) which spontaneously regressed over a period of 2 years. The immunological and molecular characterizations of expanded cells showed the CD3+,CD8+,HNK-1+ phenotype, a polyclonal organization of the T-cell receptor beta-chain gene and normal natural killer activity. At the time of presentation, spot and blot hybridization techniques revealed the presence of viral hepatitis B virus (HBV) DNA sequences only in highly enriched CD4+ T cells, while proliferating GL were negative.

Functional analysis of cytotoxic cells in patients with acute nonlymphoblastic leukemia in complete remission.

In the current study, we investigated the cytotoxic ability of peripheral blood mononuclear cells (PBMC) recovered from patients with acute nonlymphoblastic leukemia (ANLL) in complete remission (CR) against natural killer (NK)-sensitive, NK-resistant, autologous and allogeneic leukemic target cells taken at diagnosis. Our purpose was to define the role played by cytotoxic mechanisms in the control of leukemic cell growth in ANLL. Experiments were carried out at resting conditions and after in vitro activation with recombinant interleukin-2 (rIL-2) and anti-CD3 monoclonal antibody (moAb).

Pulmonary alveolar macrophages from patients with active sarcoidosis express type IV collagenolytic proteinase. An enzymatic mechanism for influx of mononuclear phagocytes at sites of disease activity.

Alveolar macrophages (AMs) recovered from the bronchoalveolar lavage (BAL) of 44 patients with sarcoidosis were evaluated for their ability to release type IV collagenolytic metalloproteinase (IV-Case). This enzyme, which is produced by peripheral blood monocytes (PBMs) but not by tissue macrophages, degrades type IV collagen, the major structural component of vessel wall basement membranes, and helps to promote the migration of PBMs from the blood compartment to peripheral tissues. Our results demonstrated that AMs from patients with active sarcoidosis released significantly increased levels of IV-Case with respect to patients with inactive disease and control subjects.

Generation of superoxide anion by alveolar macrophages in sarcoidosis: evidence for the activation of the oxygen metabolism in patients with high-intensity alveolitis.

We studied superoxide anion (O2) generation by alveolar macrophages (AM) isolated from bronchoalveolar lavages (BAL) of patients with sarcoidosis, and assayed immediately after the isolation or after maintenance in culture for 2 days. In assays of cells freshly isolated from BAL, AM of patients with active sarcoidosis with a high-intensity lymphocytic alveolitis produced more O2- in response to phorbol myristate acetate than AM of patients with inactive sarcoidosis. Also, after 2 days of cultivation sarcoid AM were heterogeneous in their capability to metabolize oxygen, although both AM of active and inactive sarcoid patients produced higher amounts of O2- than AM of healthy subjects.

Hairy cell sensitivity to the lysis in vitro. Role of the anti-CD3 antibody in generating a susceptibility to the lysis.

Experiments herein reported were designed to clarify the degree of sensitivity of hairy cells to lysis in vitro. The cytotoxic capacity of peripheral blood lymphocytes from hairy cell leukemia patients against autologous and/or allogenic hairy cells was tested both at resting conditions and after in vitro stimulation. While effectors activated by interferon alpha, lectins, or interleukin-2 were unable to induce a lysis of hairy cells, in some cases we were successful in eliciting a definite lysis of these cells by triggering the effector cells with anti-CD3 monoclonal antibodies.

Release of natural killer cytotoxic factor in patients with lymphoproliferative disease of granular lymphocytes.

To further investigate the mechanisms accounting for defective natural killer (NK) activity observed in the majority of patients with lymphoproliferative disease of granular lymphocytes (LDGL), we have studied the generation of natural killer cytotoxic factor (NKCF) from peripheral blood lymphocytes recovered from twelve LDGL patients. On the basis of their cytotoxic activity against the K-562 target cells, cases under study were separated in two groups. Cells from five patients, referred to as NK+, were found to exhibit high levels of NK-cell mediated cytotoxicity; cells from seven patients, referred to as NK-, despite their ability to bind to the K-562 targets, displayed a defective NK function.

Increased levels of soluble CD8 molecule in the serum of patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related disorders.

In this study we investigated the serological levels of the soluble form of the CD8 molecule (s-CD8) in 97 human immunodeficiency virus (HIV) seropositive patients. The control groups included 20 normal heterosexual subjects and 19 healthy seronegative subjects belonging to risk groups for AIDS. Our results show that patients with HIV infection have significantly higher levels of s-CD8 U/ml than the control groups.