Decreased functional T lymphocyte-mediated cytokine responses in patients with chemotherapy-induced neutropenia.

OBJECTIVES: The degree of immunosuppression in patients with haematological malignancies treated with chemotherapy is routinely measured as number of circulating cells (preferable neutrophils) in peripheral blood. A parallel decline in the number of T cells is expected, but a possible alteration in their functionality has been less well explored. The ability of T cells to secrete more than one cytokine simultaneously is known to indicate protective immunity. The aim of this study was to determine whether the function of circulating T cells is altered in patients with chemotherapy-induced neutropenia. DESIGN, SETTING AND SUBJECTS: In this cross-sectional study, we used the FluoroSpot assay to investigate the proportion of T cells secreting either interferon-γ or interleukin-2, or both cytokines simultaneously, after anti-CD3 stimulation. Peripheral blood mononuclear cells from 53 adult patients with chemotherapy-induced neutropenia and 20 healthy individuals were investigated. RESULTS: There were significantly fewer T cells secreting interferon-γ in patients with neutropenia compared with healthy control subjects (P = 0.02), but the difference was greatest for dual cytokine-secreting T cells (P = 0.001). Furthermore, the amount of secreted cytokine per T cell appeared to be reduced in patients, compared with control subjects. CONCLUSION: Our results suggest that the functionality of T cells is altered in patients with haematological malignancies with chemotherapy-induced neutropenia. In parallel with a decline in T cell count, this may further increase the risk of severe infections.

FluoroSpot Analysis of TLR-Activated Monocytes Reveals Several Distinct Cytokine-Secreting Subpopulations.

Monocytes have long been considered a heterogeneous group of cells both in terms of morphology and function. In humans, three distinct subsets have been described based on their differential expression of the cell surface markers CD14 and CD16. However, the relationship between these subsets and the production of cytokines has for the most part been based on ELISA measurements, making it difficult to draw conclusions as to their functional profile on the cellular level. In this study, we have investigated lipoteichoic acid (LTA)- and lipopolysaccharide (LPS)-induced cytokine secretion by monocytes using the FluoroSpot technique. This method measures the number of cytokine-secreting cells on the single-cell level and uses fluorescent detection, allowing for the simultaneous analysis of two cytokines from the same population of isolated cells. By this approach, human monocytes from healthy volunteers could be divided into several subgroups as IL-1ß, IL-6, TNF-α and MIP-1ß were secreted by larger populations of responding cells (25.9-39.2%) compared with the smaller populations of GM-CSF (9.1%), IL-10 (1.3%) and IL-12p40 (1.2%). Furthermore, when studying co-secretion in FluoroSpot, an intricate relationship between the monocytes secreting IL-1ß and/or IL-6 and those secreting TNF-α, MIP-1ß, GM-CSF, IL-10 and IL-12p40 was revealed. In this way, dissecting the secretion pattern of the monocytes in response to TLR-2 or TLR-4 stimulation, several subpopulations with distinct cytokine-secreting profiles could be identified.