W. Oster

Granulocyte-macrophage colony-stimulating factor induces cytokine secretion by human polymorphonuclear leukocytes.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is known as an inducer of proliferation and functional activation of myeloid cells. This study was carried out to characterize the effects of GM-CSF on polymorphonuclear leukocytes (PMN) more extensively. Using Northern blot analysis, we show that PMN are able to accumulate mRNAs for different cytokines, including tumor necrosis factor-alpha (TNF-alpha); G-CSF, and M-CSF, all of which are involved in inflammation and hematopoiesis. Biological assays and immunoassays demonstrate that PMN translate these mRNAs, except TNF-alpha, into secretory proteins. However, the expression of these cytokines is dependent on stimulation by exogenous signals, preferentially provided by the T cell-derived lymphokine GM-CSF. Stimulation of hematopoiesis and amplification of defense mechanisms after T cell activation thus might involve not only monocytes but also PMN, a cell type previously believed to be biosynthetically inactive.

Participation of the cytokines interleukin 6, tumor necrosis factor-alpha, and interleukin 1-beta secreted by acute myelogenous leukemia blasts in autocrine and paracrine leukemia growth control.

Autonomous in vitro growth of myeloid leukemic colony-forming cells may in part result from autocrine production of colony-stimulating factors (CSF). Some acute myeloid leukemia (AML) samples, however, fail to synthesize CSF despite growing autonomously in agar, and are therefore believed to bypass CSF requirements. Cytokines such as IL-6, tumor necrosis factor (TNF)-alpha, and IL-1, products of cells of the myeloid lineage, are known to be involved in growth control of myeloid progenitor cells. Since these molecules may also contribute to autocrine and paracrine growth regulation of myeloid leukemias, we screened a series of AML for cytokine production. In addition, possible roles of IL-6, TNF-alpha, and IL-1 in growth control of AML were investigated in vitro. We show that a substantial proportion of AML cells produce IL-6, TNF-alpha, and IL-1-beta and use these mediators to stimulate their growth by disparate mechanisms: IL-6 acts as a costimulator to enhance CSF-induced clonogenicity of AML blasts. TNF-alpha induces CSF production by endothelial cells and may therefore provide a paracrine loop to support leukemia growth.

Lymphokine activated killer cells

SummaryVarious subpopulations of human leukocytes may be induced by lymphokines to exert cytotoxic activity. In man major histocompatibility complex non-restricted tumor cell lysis by interleukin-2 (IL-2) induced peripheral blood lymphocytes is attributed mainly to natural killer cells. These T cell receptor negative large granular lymphocytes are called lymphokine activated killer (LAK) cells. In order to explore the potential of LAK cells in tumor therapy, several clinical studies have been conducted, using IL-2 alone or in combination with ex vivo IL-2-activated peripheral blood lymphocytes. Objective responses have reproducibly been achieved only in renal cell carcinoma and malignant melanoma and were associated with considerable toxicity. In view of restricted efficacy and increasing doubts as to whether LAK cells indeed account for the in vivo observed responses, more recent strategies focus on tumor antigen specific cytotoxic T cells or tumor infiltrating lymphocytes. Successful translation of this approach into clinical practice, however, may be dependend on some basic problems of tumor immunology to be solved which were thought to be by-passed by the LAK cell approach.

A phase-II study of low-dose cyclophosphamide and recombinant human interleukin-2 in metastatic renal cell carcinoma and malignant melanoma

SummaryRecent preclinical and clinical studies that have demonstrated antitumor activity of high-dose recombinant interleukin-2 (rIL-2), and animal models that demonstrated a synergistic effect of low-dose cyclophosphamide, led us to study rIL-2 (Cetus Corp., Emeryville, Calif) in a phase II clinical trial in combination with low-dose cyclophosphamide in 32 patients, 18 with malignant melanoma and 14 with renal cell carcinoma. rIL-2 was given once daily at 3×106 U/m2, as a 30-min infusion for 14 days in cycle I and for 2×5 days in cycles II and III respectively; if tolerated, the dose was increased to a maximum of 6×106 U m−2 day−1; the cycles, separated by 1 week treatment-free intervals, were preceded each by a single i.v. bolus of cyclophosphamide at 350 mg/m2. The most prominent side-effects encountered in this trial consisted of a capillary leak syndrome, myalgia and fever that required dose reduction during the first cycle in one-half of the patients. Given the limit of tolerable toxicities in a standard care unit, the regimen employed achieved minor antitumor activity. No remission was achieved in patients with renal cell carcinoma, and 15% of melanoma patients showed objective responses (partial response + minor response).

Incidence of lineage promiscuity in acute myeloblastic leukemia: Diagnostic implications of immunoglobulin and T-cell receptor gene rearrangement analysis and immunological phenotyping

Sixty-nine blood or bone marrow samples from both children and adults with acute myeloblastic leukemia (AML) were investigated to elucidate the frequency of immunoglobulin (IG) and T-cell receptor (TCR)-gene rearrangements. Non-germline configuration for the IG heavy chain (h) gene was detected in the specimens of nine patients of various subtypes according to the French-American-British classification (FAB), including FAB M1, M2, M4 and M5. Rearrangement of the IG kappa chain (k) gene was present in one of these cases which simultaneously revealed a rearranged TCR-beta (b) chain gene. In another two AML samples we found TCR-b gene rearrangements, in one case in combination with an IG-h gene rearrangement. IG-h gene rearrangements were detected in 10 cases, in one case in conjunction with an IG-kappa (k) and TCR-b gene rearrangement. A highly significant correlation between the occurrence of DNA rearrangements of the IG-h locus and nuclear staining with the enzyme terminal deoxynucleotidyl transferase (TdT) and surface expression of the CD 19 and CD 34 antigen could be identified: all 10 TdT positive AML samples rearranged IG-h. Similarly, six out of 69 AML samples exhibited surface expression of CD 19, five of these in combination with CD 34 and all of them rearranged the IG-h gene. The one leukemia with TCR-b gene rearrangement only was TdT positive as well, but did not express CD 19 or CD 34. We conclude that IG-h gene is rearranged in a substantial proportion of AML, strongly associated with a specific immunophenotype (TdT+, CD19+, CD34+), whereas TCR-b gene rearrangement appears more rarely. No positive correlation between occurrence of IG-h and TCR-b gene-rearrangements and one AML FAB-subtype was found, although a clustering of M1 and M4 FAB subtypes in the AML group showing reconstructed IG-h gene became evident.

A multicenter trial of interleukin-2 and low-dose cyclophosphamide in highly chemotherapy-resistant malignancies

The anti-tumor activity of high-dose recombinant interleukin-2 (IL-2) has been demonstrated in several recent preclinical and clinical studies. In an attempt to study possible synergistic effects with low-dose cyclophosphamide (CYC), a phase II clinical trial was initiated in 32 patients, 18 with malignant melanoma (MM) and 14 with renal cell carcinoma (RCC). The recombinant IL-2 (Cetus Corp., Emeryville, Ca, U.S.A.) was given once daily at 3 x 10(6) U/m2, as a 30-min infusion for 14 days in cycle I and for five days twice in cycles II and III, respectively; if tolerated, the dose was escalated to a maximum of 6 x 10(6) U/m2/day; the cycles, separated by 1-week treatment-free intervals, were each preceded by a single i.v. bolus of CYC at 350 mg/m2. The most prominent side-effects encountered in this trial consisted of a capillary leak syndrome, myalgia and fever requiring dose reduction in half of the patients during the first cycle. Given the limit of tolerable toxicities in a standard care unit, the regimen employed achieved minor anti-tumor activity. No objective responses were achieved in patients with RCC and a 15% remission rate (PR + MR) was seen in melanoma patients.

MACOP-B chemotherapy for the treatment of high grade and intermediate grade Non Hodgkin's lymphoma

SummaryBetween Nov. 1985 and Nov. 1988, sixty-three patients with high grade malignant (hg) and intermediate grade malignant (img) Non Hodgkins Lymphoma (NHL) were treated with MACOP-B (methotrexate, doborubicin, cyclophosphamide, vincristine, prednison and bleomycin). Thirty-seven patients received MACOP-B as an upfront treatment modality, whereas twenty-six patients had relapsed disease and received MACOP-B as a salvage protocol. Four weeks after termination of therapy, 75% of patients with de novo NHL and 72% of the patients with relapsed NHL were in complete remission (CR). In the group of newly diagnosed NHL, 22% achieved partial remission (PR) and 3% no change (NC), whereas in the group with relapsed disease 14% had PR and 14% had progressive disease (PD). At a medium follow-up of 12 months (range 1 month to 33 months), 74% of patients with de novo NHL continued to be in CR whereas the continuous CR rate in patients with relapsed disease was 35%. Overall survival after 30 months of observation for the patient group with de novo NHL was 75% and 40% for patients with relapsed NHL. The mean duration for completion of the projected 12 chemotherapy cycles, given in weekly intervals, was 12.9 and 13.5 weeks in upfront or salvage therapy, respectively. With low incidence of major toxicities, application of drugs on an outpatient basis, and high efficacy, MACOP-B shows substantial advantges for therapy of de novo and relapsed NHL.

Monocyte Interleukin-1 Secretion Is Regulated by the Sequential Action of γ-Interferon and Interleukin-2 Involving Monocyte Surface Expression of Interleukin-2 Receptors

Interleukin-1 (IL-1) is a polypeptide synthesized as a high-mol.-wt. precursor and subsequently secreted after proteolytic cleavage to 17500-dalton active forms in murine [1] and human cells [2]. Recently, cDNAs for murine [3] and for two distinct human IL-1 species, IL-1α and IL- 1β, have been isolated, sequenced, and cloned [2, 4].

Gamma-Interferon Regulates Secretion of G-CSF in Human Monocytes on the Transcriptional Level

The production of colony stimulating factors (CSF) for granulocytes and monocytes is integrated into a network of communicating soluble messenger molecules resulting from T-cell/monocyte interactions. We assessed the capactiy of gamma-Interferon to modulate monocyte secretion of CSF by colony assays and Northern blot analysis to hybridize monocyte RNA with cDNA probes of different CSF-types. Whereas mRNA for GM-CSF was undetectable in untreated and gamma-IFN treated peripheral blood monocytes, the constitutive expression of mRNA for G-CSF and subsequent production of a CSF with biological activities similar to G-CSF could highly be enhanced by exposure of monocytes to gamma-IFN.

Mechanisms of Autocrine and Paracrine Growth Control in Acute Myelogenous Leukemia

Blast cells of a high proportion of patients with acute myelogenous leukemia (AML) proliferate in response to exogenous hematopoetic growth factors, both in vitro [9, 14, 26, 36, 48, 65] and in vivo [20]. Whereas leukemic colony-forming cells (L-CFCs) from most patients share their growth factor dependence with normal committed myeloid progenitor cells (CFU-GMs), some AML samples autonomously form colonies in agar and are therefore believed to bypass growth factor requirements [17, 42, 72]. Autocrine growth factor production has been identified as one mechanism used by AML blasts to supply various growth-promoting molecules. Moreover nontransformed accessory bone marrow cells have been shown to be inducible for production of growth-promoting factors by AML-derived mediators. This paper summarizes the current knowledge of autocrine and paracrine growth-promoting mechanisms in AML whereby leukemic cells may achieve selective growth advantages and includes recent data supporting the concept that various cytokines may act in concert to induce optimal leukemic growth.