Biology and Clinical Applicability of Plasma Thymus and Activation-Regulated Chemokine (TARC) in Classical Hodgkin Lymphoma

Thymus and activation-regulated chemokine (TARC) is produced by different cell types and is highly expressed in the thymus. It plays an important role in T cell development, trafficking and activation of mature T cells after binding to its receptor C-C chemokine receptor type 4 (CCR4) and consecutive signal transducer and activator of transcription 6 (STAT6) activation. Importantly, TARC is also produced by malignant Hodgkin and Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (cHL). In cHL, HRS cells survive and proliferate due to the micro-environment consisting primarily of type 2 T helper (Th2) cells. TARC-mediated signaling initiates a positive feedback loop that is crucial for the interaction between HRS and T cells. The clinical applicability of TARC is diverse. It is useful as diagnostic biomarker in both children and adults with cHL and in other Th2-driven diseases. In adult cHL patients, TARC is also a biomarker for treatment response and prognosis. Finally, blocking TARC signaling and thus inhibiting pathological Th2 cell recruitment could be a therapeutic strategy in cHL. In this review, we summarize the biological functions of TARC and focus on its role in cHL pathogenesis and as a biomarker for cHL and other diseases. We conclude by giving an outlook on putative therapeutic applications of antagonists and inhibitors of TARC-mediated signaling.

[EVALUATION OF THE RELATIONSHIP BETWEEN THE SEVERITY OF SOLID FOOD PROTEIN-INDUCED ENTEROCOLITIS SYNDROME AND POST-EMETIC SERUM THYMUS AND ACTIVATION-REGULATED CHEMOKINE LEVELS]

BACKGROUND

We reported that post-emetic serum thymus and activation-regulated chemokine (TARC) levels may be a potential biomarker to diagnose solid food protein-induced enterocolitis syndrome (FPIES). However, there are no reports on the relationship between FPIES severity and serum TARC levels.

METHODS

The subjects were 13 cases of FPIES (hen's egg=10, Wheat=1, rice=1, short-neck clam=1) for a total of 22 events (7 emergency outpatient visits, 9 positive and 6 negative results of oral food challenge test). Serum TARC levels at 6 and 24 h after antigen ingestion were compared between the symptomatic and asymptomatic events and the mild-moderate and severe events. We also evaluated the correlation between vomiting duration and serum TARC levels.

RESULTS

The median serum TARC (pg/ml) in the asymptomatic, mild-moderate, and severe events were 546, 1093, and 3127 at 6 h after ingestion, and 910, 2053, and 6496 at 24 h after ingestion, respectively. The serum TARC level was significantly higher in the symptomatic events than the asymptomatic events, and it was significantly higher in the severe events than the mild-moderate events (p < 0.01). There was a moderate correlation between serum TARC levels and vomiting duration.

CONCLUSION

Post-emetic serum TARC correlates with the severity of FPIES. It is expected that this information will lead to an objective evaluation of the severity of FPIES.