Immunolocalization of intracellular interleukin-4 in normal human peripheral blood basophils.
The question as to whether other cell types apart from helper T lymphocytes are capable of producing interleukin-4 (IL-4) has gained much interest over the last years. Recent studies indicate that human basophils also produce IL-4, although direct proof is missing so far. In this study we demonstrate the presence of IL-4 in the cytoplasm of in vitro activated human peripheral blood basophils derived from normal donors. Cytokine-producing cells were revealed at the single-cell level by intracellular immunofluorescence staining using IL-4-specific monoclonal antibodies. Basophils showed a characteristic, apparently granular staining pattern easily discerned from the eccentric dot-shaped staining pattern in activated T cells used in control experiments. Cell counts following priming with IL-3 and stimulation with polyclonal sheep anti-IgE antibody or the anaphylatoxin C5a revealed a significant increase in IL-4-positive basophils to about 19% as compared with unprimed, unstimulated control cells (6%). The amount of IL-4 in the supernatant of these cell preparations paralleled these observations with an at least five- to sevenfold increase following stimulation as compared with control cells (< 5 ng/ml). Using confocal scanning laser microscopy, the intracellular presence of IL-4 was confirmed, and the cells were identified as being basophils on terms of their characteristic multilobed nucleus. This observation was supported by double labeling studies using antibodies to IL-4 and to the high-affinity IgE receptor (Fc epsilon R1). Interestingly, stimulation of cells led to a decrease in the number of Fc epsilon R1-positive cells. The above results show direct evidence that IL-4 is produced by activated human basophils.
Mueller
R
R
Ciba Geigy, Research Department, Basel, Switzerland.
Heusser
C H
CH
Rihs
S
S
Brunner
T
T
Bullock
G R
GR
Dahinden
C A
CA
D001491:Basophils / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D015847:Interleukin-4 / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D018613:Microscopy, Confocal; D017455:Receptors, IgE / Q000378:metabolism
D017455:Receptors, IgE; D015847:Interleukin-4