About CXCL9
What is CXCL9 and why does it matter in MAS?
CXCL9 makes IFNγ-driven hyperinflammation measurable1
Chemokine (C-X-C motif) ligand 9 (CXCL9) is a type of cytokine released almost exclusively by interferon gamma (IFNγ)-activated macrophages.1 Its primary function is to attract T cells into inflamed tissues.2
IFNγ itself is difficult to reliably measure in the blood. CXCL9—which is more stable and easily measurable—is a surrogate marker of IFNγ activity.1,2 CXCL9 measurement is a way to translate underlying immune activation into clinically meaningful information to support diagnosis and monitor disease activity.1
Explore the digital deck of CXCL9 facts below
CXCL9 can help differentiate MAS from flares and detect early hyperinflammation.4
CXCL9 is more specific than traditional inflammatory markers
Traditional inflammatory markers such as ferritin, CRP, and LDH reflect broad immune activation.5 CXCL9 adds a more biologically specific signal of IFNγ-driven pathology to existing clinical assessments.2
CXCL9 testing is intended to complement, not replace, standard laboratory markers.5
CXCL9: A dynamic marker of disease activity
Currently, no universally accepted cutoff exists for CXCL9 levels.1 Tracking CXCL9 level trends alongside standard laboratory markers can support an assessment of disease activity and trajectory.5
A published example of differential serum CXCL9 levels in MAS and active sJIA
Evaluating
CXCL9 levels
In a cross-sectional analysis of blood samples from patients with systemic juvenile idiopathic arthritis (sJIA), including those with active macrophage activation syndrome (MAS), active sJIA without MAS, and healthy controls, researchers measured levels of IFNγ and IFNγ-induced CXCL9. Their findings suggest that IFNγ is a key driver of the hyperinflammation seen in MAS, but not the persistent autoinflammation of underlying sJIA.3
Serum levels of IFNγ and CXCL9 are elevated in MAS in sJIA3
MAS | Active sJIA | |
IFNγ pg/mL (range) | 15.4 | 4.9 |
CXCL9 pg/mL (range) | 13,392 | 837 |
CXCL9 levels have been shown to correlate with several laboratory features of MAS in sJIA and decrease with reductions in disease activity.2
CXCL9 testing sites
There is growing recognition of testing for CXCL9 as a biomarker for IFNγ activity.2 The following organizations offer CXCL9 testing to help with identifying MAS:
Machaon Diagnostics | |
Website | |
Turnaround time | STAT: <24 hours |
Lab hours | 24/7 |
Phone | 1-800-566-3462 |
Fax | 510-839-6153 |
Cincinnati Children’s Hospital | |
Website | |
Turnaround time | 4 days |
Lab hours | Mon-Fri, 8:00 AM to 5:00 PM (ET) |
Phone | 513-636-4685 |
Fax | 513-636-3861 |
This is not an exhaustive list of labs offering CXCL9 testing. Please check for the availability of this test within your own institution prior to contacting these sites.