Non-thermal plasma prevents IgE-mediated Ca²⁺ influx and allergic response in RBL-2H3 cells

Non-thermal plasma (NTP) has been reported to exhibit various biological effects, including hemostatic, anticancer, and wound-healing properties. However, the effects of NTP on allergic responses in mast cells and basophils have not been sufficiently investigated. In this study, we examined the effects of NTP on immunoglobulin E (IgE)-mediated degranulation and cytokine expression in the basophilic cell line RBL-2H3. To induce degranulation and cytokine expression as part of allergic reactions, we treated the cells with 2,4-dinitrophenylated bovine serum albumin (BSA) after sensitization or with the Ca²⁺ ionophore A23187. Cells were also treated with NTP-activated acetated Ringer's solution (PAA). Degranulation was measured by quantifying the β-hexosaminidase (β-hex) activity. PAA treatment inhibited both antigen stimulation- and A23187-induced degranulation in RBL-2H3 cells, and suppressed antigen-induced mRNA expression of cytokines, including IL-4, IL-6, and TNF-α. Antigen stimulation caused disintegration of the F-actin cytoskeleton, and PAA treatment suppressed these morphological changes. Cotreatment with PAA and catalase blocked the inhibitory effects of PAA on antigen stimulation-induced degranulation. PAA also inhibited A23187-induced extracellular signal-regulated kinase (ERK) phosphorylation and antigen stimulation- or store-operated Ca²⁺ entry inducer thapsigargin-induced cellular Ca²⁺ influx. These results indicate that PAA effectively inhibits immunological responses in allergic cells - such as degranulation and cytokine expression - by suppressing ERK phosphorylation and Ca²⁺ influx. These findings suggest that PAA may be an effective therapeutic option for treating patients with allergic diseases.