Immunostimulatory Effects of β-glucan Purified from Paenibacillus polymyxa JB115 on Mouse Splenocytes

We investigated the effects of beta-glucan purified from Paenibacillus polymyxa JB115 on the viability and proliferation of splenocytes. Splenocytes play a critical role in host immunity. MTT assays and trypan blue exclusion tests revealed that beta-glucan significantly promoted the viability and proliferation of splenocytes over a range of concentrations. However, there was no specific subset change. beta-glucan protected splenocytes from cytokine withdrawal-induced spontaneous cell death. For further mechanistic studies, ELISA assay revealed that beta-glucan enhanced the expression of anti-apoptotic molecules and interleukin 7 (IL-7), a cytokine critical for lymphocyte survival. We also investigated the IL-2 dependency of beta-glucan-treated splenocytes to determine if treated cells could still undergo clonal expansion. In flow cytometric analysis, beta-glucan induced increased levels of the activation marker CD25 on the surface of splenocytes and beta-glucan-treated splenocytes showed higher proliferation rates in response to IL-2 treatment. This study demonstrates that beta-glucan can enhance the survival of splenocytes and provides valuable information to broaden the use of beta-glucan in research fields.