Differential sensitivity of lymphocyte subpopulations to non-thermal atmospheric-pressure plasma

Non-thermal atmospheric-pressure plasmas can possibly be used for several applications in particular in medicine. Plasma treatment can be applied to living tissues and cells, e.g., to induce apoptosis and growth arrest in tumour cells or to improve wound healing. However, detailed investigations of plasma–cell interactions are strongly needed. It is not yet clear whether plasmas will be useful in stimulating immune cells to change their behaviour or function. Therefore, this study focused on the influence of non-thermal atmospheric pressure plasma on cell surface molecules of rat spleen mononuclear cells (MNC) as first important step to gain insight into plasma–immune cells interactions. Rat spleen MNC were treated with plasma by surface dielectric barrier discharge (DBD) at atmospheric pressure in air or argon. Lymphocyte subpopulations and expression of L-selectin, ICAM-1 and LFA-1α expression on T-cells were analysed by flow cytometry 1–48 h after plasma treatment. Plasma changed the ratio of T- and B-cells in favour of B-cells. Of the T-cells the helper T-cells were reduced while cytotoxic T-cells were less affected. L-selectin expressing T-cells were significantly reduced already 1 h after plasma treatment and that of ICAM-1+ and LFA-1α+T-cells only after 4 h. These effects were time dependent and less dramatic when using DBD/argon plasma. In conclusion, different lymphocyte subpopulations show different sensitivity to plasma. Adhesion molecules as L-selectin, ICAM-1 and LFA-1α are down regulated by plasma. Whether these results can be used to modify lymphocyte homing or to activate MNC for different applications remains to be clarified.