Syk deficiency in nonreleaser basophils.
BACKGROUND
Peripheral blood basophils from 10% to 20% of donors fail to degranulate in response to cross-linking the high-affinity IgE receptor FcepsilonRI. The molecular mechanisms underlying the nonreleaser phenotype have not been established.


OBJECTIVE
Our aim was to compare the expression of FcepsilonRI-associated protein tyrosine kinases between nonreleaser and releaser basophils.


METHODS
With use of Western blotting we investigated Syk and Lyn protein levels in highly purified basophils from 3 anti-IgE nonreleasers and 2 releasers.


RESULTS
We identified 3 healthy nonatopic donors whose nonreleaser basophils express FcepsilonRI normally but fail to express protein for the tyrosine kinase Syk, which is implicated in the initiation of FcepsilonRI-mediated secretion. Protein levels for the tyrosine kinase Lyn are somewhat reduced but not absent in nonreleaser basophils. Levels of Lyn and Syk protein are similar in B cells, eosinophils, and neutrophils from releaser and nonreleaser donors. During these studies one nonreleaser "converted" into a releaser with concomitant basophil Syk expression.


CONCLUSIONS
The absence of detectable Syk could explain the nonreleaser phenotype of basophils from some donors.
Kepley
C L
CL
Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, USA.
Youssef
L
L
Andrews
R P
RP
Wilson
B S
BS
Oliver
J M
JM
D000293:Adolescent; D000328:Adult; D000906:Antibodies / Q000494:pharmacology; D001491:Basophils / Q000201:enzymology* / Q000378:metabolism*; D004792:Enzyme Precursors / Q000097:blood / Q000172:deficiency* / Q000235:genetics; D006636:Histamine Release / Q000187:drug effects; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008875:Middle Aged; D011505:Protein-Tyrosine Kinases / Q000097:blood / Q000172:deficiency* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D017455:Receptors, IgE / Q000276:immunology / Q000502:physiology; D000072377:Syk Kinase
D000906:Antibodies; D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D017455:Receptors, IgE; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase