A fast procedure for the detection of defects in Toll-like receptor signaling.
OBJECTIVE
Inborn defects in Toll-like receptor signaling are recently described primary immunodeficiencies that predispose affected children to life-threatening infections. Patients with interleukin-1 receptor-associated kinase-4 deficiency are prone to invasive pneumococcal disease, and patients with UNC-93B deficiency are prone to herpes simplex virus encephalitis. These genetic disorders are underdiagnosed, partly because diagnosis currently requires expensive and time-consuming techniques available at only a few specialized centers worldwide. We, therefore, aimed to develop a cheap and fast test for the detection of defects in Toll-like receptor signaling.


METHODS
We used flow cytometry to evaluate the cleavage of membrane-bound L-selectin on granulocytes in 38 healthy controls and in 7 patients with genetically defined Toll-like receptor signaling defects (5 patients with interleukin-1 receptor-associated kinase-4 deficiency and 2 patients with UNC-93B deficiency), on activation with various Toll-like receptor agonists.


RESULTS
Impaired L-selectin shedding was observed with granulocytes from all of the interleukin-1 receptor-associated kinase-4-deficient patients on activation with agonists of Toll-like receptors 1/2, 2/6, 4, 7, and 8 and with granulocytes from all of the UNC-93B-deficient patients on activation with agonists of Toll-like receptors 7 and 8. All of the healthy controls responded to these stimuli.


CONCLUSIONS
The assessment of membrane-bound L-selectin cleavage on granulocytes by flow cytometry may prove useful for the detection of primary immunodeficiencies in the Toll-like receptor pathway, such as interleukin-1 receptor-associated kinase-4 deficiency and UNC-93B deficiency. This procedure is cheap and rapid. It may, therefore, be suitable for routine testing worldwide in children with invasive pneumococcal disease and in patients with herpes simplex encephalitis.
von Bernuth
Horst
H
Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes, Institut National de la Santé et de la Recherche Médicale U550, Necker Medical School, Paris, France. vonbern@necker.fr
Ku
Cheng-Lung
CL
Rodriguez-Gallego
Carlos
C
Zhang
Shenying
S
Garty
Ben-Zion
BZ
Maródi
László
L
Chapel
Helen
H
Chrabieh
Maya
M
Miller
Richard L
RL
Picard
Capucine
C
Puel
Anne
A
Casanova
Jean-Laurent
JL
D002648:Child; D005434:Flow Cytometry; D006801:Humans; D053592:Interleukin-1 Receptor-Associated Kinases / Q000172:deficiency*; D026901:Membrane Transport Proteins / Q000172:deficiency*; D015398:Signal Transduction; D013997:Time Factors; D051193:Toll-Like Receptors / Q000235:genetics*
D026901:Membrane Transport Proteins; D051193:Toll-Like Receptors; C454130:UNC93B1 protein, human; C507773:IRAK4 protein, human; D053592:Interleukin-1 Receptor-Associated Kinases