Secretion of IL-4 from human basophils. The relationship between IL-4 mRNA and protein in resting and stimulated basophils.
Purified human basophils have been examined for secretion of IL-4 protein and expression of IL-4 mRNA after stimulation with several secretagogues. In general, these studies used a 15-min preincubation with IL-3, before challenge with secretagogues. Under these conditions, IL-4 release averaged 30 pg/10(6) basophils (range 4-70) after challenge with anti-IgE Ab. FMLP and C5a led to somewhat lower levels of secretion. A direct comparison of basophils at 88 to 99% purity with basophils from the same preparations, but at lower purities, showed that the amount of IL-4 secretion was proportional to the purity of the basophils. The presence of mRNA for IL-4 (as determined by reverse transcriptase-PCR, competitive reverse transcriptase-PCR, or Northern blots) was also strictly related to the purity of the basophils. IL-4 mRNA was also found to be constitutively present and was increased after stimulation. The concentration of polyclonal anti-IgE Ab required for optimal IL-4 release was somewhat less than that required for optimal histamine release. IL-4 secretion was slower (t1/2 of 1.5 h) than histamine release and was inhibited by cycloheximide. In a final series of studies, we found that IL-3 was not required for IL-4 secretion; a short 15-min preincubation with IL-3 resulted in the same or slightly less IL-4 release than no treatment with IL-3. In contrast, an 18-h pretreatment with IL-3 resulted in a nearly tenfold increase in IL-4 secretion. We conclude that human basophils secrete IL-4 in response to several secretagogues and that IL-3 priming is not necessary to observe IL-4 secretion.
MacGlashan
D
D
Johns Hopkins Asthma and Allergy Center, Baltimore, MD 21224.
White
J M
JM
Huang
S K
SK
Ono
S J
SJ
Schroeder
J T
JT
Lichtenstein
L M
LM
D001483:Base Sequence; D001491:Basophils / Q000737:chemistry / Q000378:metabolism*; D002478:Cells, Cultured; D006801:Humans; D007073:Immunoglobulin E / Q000502:physiology; D007377:Interleukin-3 / Q000494:pharmacology; D015847:Interleukin-4 / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis*; D015398:Signal Transduction
D007377:Interleukin-3; D012333:RNA, Messenger; D015847:Interleukin-4; D007073:Immunoglobulin E