The soluble form of CD83 is present at elevated levels in a number of hematological malignancies.

Recombinant forms of soluble CD83 (sCD83) inhibit anti-tumor responses. In this analysis of circulating sCD83 levels we report that although >95% of acute myeloid leukemia (AML) and multiple myeloma (MM) patients have normal or only weakly elevated sCD83 levels, 20% of chronic lymphocytic leukemia (CLL) and 5/7 mantle cell lymphoma (MCL) patients have significantly elevated levels (>1 ng/ml). Isolated CLL cells both weakly expressed membrane CD83 (mCD83), and released sCD83 during in vitro culture. We conclude that malignant cells are a potential source of sCD83 and that it may have functional and/or prognostic significance in hematological malignancies, particularly CLL and MCL.