Recent studies have suggested that T cells restricted to nonclassical MHC class I-like CD1 molecules may be involved in immune surveillance of hematological malignancies [3] [4] [5] [6] . CD1 molecules are nonclassical MHC class I-like molecules that present lipid antigens to T cells, triggering a specific immune response. Of the five CD1 isoforms (CD1a, CD1b, CD1c, CD1d, and CD1e) expressed in human tissue, only CD1c and CD1d are expressed in B cells [7] . The T cell receptors (TCRs) of T cells that recognize CD1c are indistinguishable from those that recognize MHC class I or II complexes. Most CD1c-restricted T cells appear to be TH-1-like cells that provide adaptive immunity to microbial-lipid antigens [8] . In contrast, CD1d presents lipid antigens to natural killer T (NKT) cells. The best characterized CD1d-restricted NKT cells in humans are the invariant NKT (iNKT) cells, also known as type I NKT cells. These cells are characterized by the expression of an invariant Va24Ja18 chain paired to a semi-invariant Vb11 chain [9] . Two distinct functional subsets of human iNKT cells are recognized in terms of cytokines production and cytotoxic activation. CD42 iNKT cells are more likely to be cytotoxic and produce TH-1 type cytokines, whereas CD41 iNKT cells are more likely to produce both TH-1 and TH-2 type cytokines after stimulation [10] . Several studies have shown the impor-tance of iNKT cells in B cell malignancies [4] [5] [6] . In chronic lymphocytic leukemia (CLL), CD1d1 tumor cells loaded with aGalCer can activate iNKT cells and in turn induce cell death of tumor cells [4] . Malignant multiple myeloma is characterized by a reversible functional defect in iNKT cells in comparison with nonprogressive myeloma and premalignant myeloma [5] . Furthermore, iNKT cells were shown to induce effective antilymphoma responses and were essential for the survival of mice in murine lymphoma models [6] . The role of iNKT cells in the immune surveillance in cHL is unknown. Here, we examined the expression of CD1c and CD1d in HRS cells and tumor infiltrating cells in 44 cHL cases, as well as in four cHL cell lines. Furthermore, we studied the presence of iNKT cells in cell suspensions of 10 cHL cases.