NCAM1 and lymphopenia: Patients with sarcoidosis often disclose a PB lymphopenia and research findings suggest that lymphocytes are depleted in PB due to increased infiltration in affected organs including the lung.21 22 Thus, it seems as if lung and PB lymphocytes can migrate between compartments, and an attractive explanation to the findings reported here on CD56+ T cells could be an influx of these cells from the circulation to the lung.