Fabrications of boron-containing apatite ceramics via ultrasonic spray-pyrolysis route and their responses to immunocytes

Immunotherapy without side effects has been expected as a novel medical treatment for cancer. However, drugs such as cytokines typically used for immunotherapy are very expensive. Therefore, we propose the concept of immunoceramics that affect the immune system. Previous studies have shown that polymers including the phenylboronic acid group activate lymphocytes. This activation may be due to interaction between the sugar chains in cells and the OH group in B(OH)3 formed via dissociation of the BO2 group. In the present study, boron-containing apatite (BAp; Ca9.5+0.5x{(PO4)6−x(BO3)x}{(BO2)1–xOx} (0 ≤ x ≤ 1)) was successfully fabricated via the ultrasonic spray-pyrolysis (USSP) route. We examined the material properties of the BAp ceramics with an aim to application as immunoceramics and the responses of immune cells to the BAp ceramics. The crystalline phases of the BAp ceramics included the apatite phase and infrared (IR) absorption of BO2 and BO3 groups was detected in the BAp ceramics. The cellular response of immune cells derived from mice spleens to dense BAp ceramics was examined next. The proportion of helper T cells and killer T cells on BAp (x = 0.4) ceramics increased compared to that on hydroxyapatite (Ca10(PO4)6(OH)2; HAp) ceramics and on a control. These results indicate that BAp (x = 0.4) ceramics fabricated via the USSP route can be expected to act as immunoceramics that can affect the immune system.