PO27 - PD‑1 and TIM‑3 on NK cells in sarcoidosis: stable across sex and stage, with specific associations to T-cell activation markers.
Iwona Kwiecień (Poland)1; Elżbieta Rutkowska (Poland)1; Rafał Sokołowski (Poland)2; Joanna Bednarek (Poland)2; Karina Jahnz-Różyk (Poland)2; Piotr Rzepecki (Poland)3; Agata Raniszewska (Poland)1;
1 - Laboratory of Flow Cytometry, Department of Internal Medicine and Hematology, Military Institute of Medicine- National Research Institute, Warsaw, Poland; 2 - Department of Internal Medicine, Pulmonology, Allergology, Clinical Immunology and Rare Diseases, Military Institute of Medicine- National Research Institute, Warsaw, Poland; 3 - Department of Internal Medicine and Hematology, Military Institute of Medicine- National Research Institute, Warsaw, Poland;
Keywords: Natural killer cells; Immune checkpoints; T-cell activation markers;
Select the theme: Genetics and Immunopathology: Advances in Contemporary Understanding and Prospects for Future Research
Type: Original Papers
Presentation: Poster Presentation

Introduction: Natural killer (NK) cells may modulate granulomatous inflammation in sarcoidosis (SA), but their role in the lymph node (LN) microenvironment remains poorly defined. Inhibitory receptors such as PD-1 and TIM-3 regulate NK function and may interact with local T-cell activation, a key driver of granuloma formation.

Objectives: To evaluate PD‑1 and TIM‑3 expression on NK cells in SA LNs, compare their levels across sex and stage, and determine whether NK checkpoint expression correlates with T‑cell activation within the LN microenvironment.

Materials and Methods: Fifty‑six newly diagnosed SA patients (women n=17; men n=39; stage I n=21; stage II n=35) underwent EBUS/TBNA. NK cells, PD‑1 and TIM‑3 expression (as % and geometric mean fluorescence (GMF)), and T‑cell activation markers (CD38, HLA‑DR) in LN aspirates were analyzed using 13‑color flow cytometry. 

Results: NK% were significantly higher in women (median 2.0% vs 1.4%, p=0.04). NK checkpoint expression remained stable across sex. Similarly, PD 1 NK% was comparable between stage I and II (11.8% vs 10.4%, p=0.75), as was TIM‑3 NK% (21.5% vs 34.9%, p=0.45). In contrast, classical sarcoidosis markers differed by stage: CD4% (34.0% vs 44.0%, p=0.01) and the CD4/CD8 ratio (2.8 vs 4.0, p=0.02), while none varied by sex. T-cell activation markers (CD38, HLA-DR) were similar except for higher CD38 CD4 GMF in stage I. Notably, subgroup‑specific associations emerged: in women, PD‑1 NK% correlated with HLA‑DR CD4% (r=0.56) and TIM‑3 NK% with HLA‑DR lymphocytes % (r=0.47) and with HLA-DR CD8 GMF (r=0.56). In stage II, TIM‑3 NK% correlated with HLA‑DR CD4% (r=0.61) and HLA-DR CD8 GMF (r=0.55). No meaningful correlations were observed in men or stage I.

Conclusions: PD-1 and TIM-3 expression on NK cells appears stable across sex and radiological stage in sarcoidosis. However, distinct correlation patterns in women and stage II patients indicate that NK–T cell interactions may be context‑dependent within the LN microenvironment of SA patients.