Effect of activated human polymorphonuclear leucocytes on T lymphocyte proliferation and viability.

Human polymorphonuclear leucocytes (PMN) are thought to be immunosuppressive. The suppressive mechanism(s) used by PMN are, however, not well defined and in this study they were analysed using T-cell responses to CD3(+) CD28 monoclonal antibodies (mAb) as a readout. We demonstrate that in vitro activated PMN (PMN(act)) can, without any T-cell interaction, induce apparent T-cell suppression by inhibiting the stimulatory capacity of the CD3 mAb.

Renal transplant recipients have elevated frequencies of circulating myeloid-derived suppressor cells.

Background: Cancer, particularly cutaneous squamous cell carcinoma (SCC), is a major cause of mortality in renal transplant recipients (RTRs). Myeloid-derived suppressor cells (MDSC) play a central role in suppressing cancer immunosurveillance but their potential mobilisation in RTRs and levels relative to those of other immunoregulatory dendritic cell (DC) populations have not been analysed.

Methods: The circulating frequencies of MDSC and DC were analysed by multicolour flow cytometry in immunocompetent patients without (n = 13) or with (ICI-SCC(Pos), n = 14) current SCC, normal donors (NDs, n = 34), chronic kidney disease patients (CKD patients, n = 22) and RTRs (n = 31).

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.