Cytokine expression of potentially active B-cell growth factors (IL-2, IL-4, IL-6) was investigated by means of mRNA-expression in 29 cases of malignant non-Hodgkin B-cell lymphomas. Strong signals were found for IL-4 and IL-6 in two and five cases, respectively, whereas the majority of the remaining cases did not show any detectable mRNA-signals for these growth factors. Comparing these results with those of the immunohistochemistry, it could be demonstrated that at least in some of these cases the signal was due to an autocrine or paracrine phenomenon of the tumour cells.

Blotting, Northern↗

PubMedDate not supplied

A comparison of assays for the response of primary human T-cells upon stimulation with interleukin-2, interleukin-4 and interleukin-7.

The most commonly used assay to quantitate the response of peripheral T-cells upon stimulation with growth factors is determination of incorporated [3H]TdR. We compared this test to three other methods: 1. direct counting of cells with a Coulter type counter as reference assay, 2. a colorimetric assay using the tetrazolium dye 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium (MTT), which is a cheap and increasingly popular non-radioactive method and 3. incorporation of the thymidine analog 5-bromo-2'-deoxyuridine detection with a monoclonal antibody on cytospins. Primary human PHA-blasts from greater than 30 healthy individuals were stimulated with IL-2, IL-4 and IL-7 and assayed with up to four different methods. We discuss the advantages and disadvantages of the assays used and the effects of differences between cell preparations. We observed no significant variations between individuals for the dose dependence, but the relative efficiency of IL-4 compared to IL-2 and IL-7 was variable. This was probably due to the slower response observed upon stimulation with this factor.

Antibodies, Monoclonal↗

PubMedDate not supplied

Transmembrane and intracellular signalling by interleukin-4: receptor dimerization and beyond.

IL-4 is a paradigmatic example for hematopoietic cytokines of the four-helix-bundle family, but offers some unusual features as well. Two receptor binding sites with different properties were identified in the molecule, which has allowed the development of antagonistic mutant proteins, and contributed to the now accepted concept that cytokines signal across membranes by crosslinking two receptor proteins. Intracellular signal transduction by IL-4 involves activation of Jak kinases and a pathway with homology to the insulin system, but not the ras/Raf-cascade. Receptor/ligand interactions are complex, because IL-4 and IL-13 share the main receptor component, and IL-4 can signal via a second type of receptor on some cells.

Animals↗