Inhibitory effect of interleukin-4 on the proliferation of acute myeloid leukemia cells with myelo-monocytic differentiation (AML-M4/M5); the role of interleukin-6.

Since interleukin-4 (IL-4) specifically inhibits monocytic colony formation in human bone marrow cultures, we investigated whether a similar inhibition could be observed in cultures of optimally stimulated acute myeloid leukemia cells with myelomonocytic differentiation (AML-M4/M5). Sensitivity to IL-4 was tested in 19 cases of AML-M4/M5, using both a 3H-thymidine incorporation assay and a clonogenic assay. Proliferation was stimulated with a combination of IL-3, granulocyte-monocyte colony-stimulating factor (GM-CSF), and conditioned medium from phytohemagglutinin-stimulated leukocytes (PHA-CM).

Induction of CD11a/leukocyte function antigen-1 and CD54/intercellular adhesion molecule-1 on hairy cell leukemia cells is accompanied by enhanced susceptibility to T-cell but not lymphokine-activated killer-cell cytotoxicity.

Some B-cell neoplasms, including hairy cell leukemia (HCL), lack expression of the adhesion molecule leukocyte function antigen-1 (LFA-1/CD11a). Additionally, HCL cells express relatively low amounts of intercellular adhesion molecule-1 (ICAM-1/CD54) and may therefore be an inappropriate target for recognition by T cells or lymphokine-activated killer (LAK) cells. We tested whether these molecules were inducible on HCL cells and if induction would lead to enhanced susceptibility to lysis by LAK cells or cytolytic T cells.

Serum monocyte colony-stimulating factor, erythropoietin and interleukin-6 in relation to pancytopenia in hairy cell leukemia.

In patients with hairy cell leukemia (HCL), we measured serum levels of monocyte colony-stimulating factor (M-CSF), interleukin-6 (IL-6), and erythropoietin during various degrees of pancytopenia characteristic for this disease. Serial sera from 12 HCL patients during various stages of the disease were analyzed. No correlation was found between the levels of M-CSF or IL-6 and the numbers of circulating monocytes or platelets, normal values of M-CSF (4 to 10 mg/l), and IL-6 (3-50 U/ml) being detected during all stages of the disease.

Interleukin 6 is a permissive factor for monocytic colony formation by human hematopoietic progenitor cells.

Since monocytes and macrophages that arise during the culture of bone marrow progenitor cells are potential sources of interleukin 6 (IL-6), we investigated whether auto- or paracrine production of this factor is involved in colony formation by normal hematopoietic progenitor cells. We added a polyclonal anti-IL-6 antiserum and a monoclonal anti-IL-6 antibody to cultures of monocyte- and T cell-depleted bone marrow cells. Colony formation was stimulated with granulocyte/monocyte-colony-stimulating factor (GM-CSF), monocyte-CSF, or IL-3.

Production of tumor necrosis factor-alpha by normal and malignant B lymphocytes in response to interferon-alpha, interferon-gamma and interleukin-4.

Since autocrine stimulation by tumor necrosis factor-alpha (TNF alpha) may be implicated in the proliferation of normal and malignant B cells, we measured the production of TNF alpha protein by these cells in response to various B-cell stimulatory agents. Purified malignant and non-malignant B lymphocytes were incubated with interleukin-4 (IL4), interferon-alpha (IFN alpha) and IFN gamma, and the supernatants were tested for the production of TNF alpha using an enzyme-linked immunosorbent assay (ELISA). Chronic lymphocytic (CLL) and prolymphocytic (PLL) leukemia cells produced low amounts of TNF alpha, irrespectively of the addition of inducers.