Plasma and Intracellular Concentration of TNF and Its Receptors in Peripheral Blood and Bone Marrow in Different Stages of B-CLL.

TNF has been proposed to play a role in the regulation of growth and death of leukemic B-CLL cells. However, the biological effects of TNF on leukemic cells, as well as its role as a prognostic factor need to be further investigated. The aim of the study was to eevaluate the correlation of TNF and its receptors in peripheral blood (PB) and bone marrow (BM) with the stage of B-CLL and some other clinical parameters. PB and BM were taken from 44 newly diagnosed, untreated B-CLL. patients. The control group consisted of 20 healthy subjects. We used flow cytometry technique to assess the capability of T and B lymphocytes to produce TNF and ELISA method to measure plasma levels of TNF and their soluble receptors. We found, that PB and BM plasma TNF concentration in the patients was significantly higher than in the healthy control (2.61 pg/ml. vs 0.62 pg/ml; and 2.91 pg/ml vs 0.75 pg/ml, respectively p<0.001). TNF concentration in PB and BM was significantly higher in Rai stage III–IV than in early stages (p<0.01). There was a correlation between the PB and BM TNF level and lymphocytosis (p<0.005) and the total tumor mass (TTM) (p<0.0001). The PB and BM TNF concentration positively correlated with the percentage of T CD3+ lymphocytes producing intracellular TNF (p<0.01).

The percentage of T cells from PB an BM expressing cytoplasmic TNF was significantly higher in patients (PB:39.11±16.97%; BM:40.73±18.19%) than in normal controls (PB:15.74±7.95%; BM:18.80±12.93%) (p< 0.00001; p<0.005, respectively). In PB and BM from B-CLL patients the percentage of CD3+ cells expressing intracellular TNF was significantly higher than the percentage of CD19+/TNF+ cells (p<0.0001). Besides, it was found that the percentage of T cells expressing cytoplasmic TNF positively correlated with the stage of disease (p<0.01). In PB positive correlation were found between the number of T CD3+/TNF+ cells and lymphocytosis (p<0.05) and TTM (p<0.001). The percentage of leukaemic B cells positive for TNF did not correlate with the stage of disease.

There was increased expression of TNF-RI and TNF-RII in leukaemic B cells in comparison to normal B-cells was observed (p<0.0001). We found positive correlation between the number of CD5+ B lymphocytes and the levels of soluble TNF-RII (sTNF-RII) (p< 0.05). The sTNF-RII levels in PB and BM significantly correlated with the stage of disease acc. Rai (p<0.0001). Furthermore, the sTNF-RII concentration positively correlated with lymphocytosis and TTM (p<0.0001). These results strongly support the key role TNF in B-CLL pathogenesis. Our results suggest that TNF may function as growth factor for B-CLL cells. CD3+T cells may be the important source of this cytokine in advanced B-CLL. It seems that changes in T cells capability to produce cytoplasmic TNF are associated with disease progression. However, further studies are required to confirm the key role of TNF in B-CLL pathogenesis.