Effects of T-helper 2-type cytokines, interleukin-3 (IL-3), IL-4, IL-5, and IL-6 on the survival of cultured human mast cells

Although stem cell factor (SCF) has been identified as a critical cytokine for the development of human mast cells from their progenitors, the effects of other cytokines on human mast cells are less well understood. We examined the effects of several cytokines on the survival of human mast cells of 100% purity generated in suspension cultures of umbilical cord blood mononuclear cells in the presence of 100 ng/mL recombinant human (rh) SCF and interleukin-6 (IL-6). Mast cells suspended in conventional serum-containing medium died over a period of 2 to 6 days after the withdrawal of SCF and IL- 6. The cells became pyknotic and underwent DNA fragmentation characteristic of apoptosis. The addition of SCF, IL-3, IL-4, IL-5, or IL-6 to the cultures in both serum-containing and serum-free medium prolonged their survival in a dose-dependent manner. Some other cytokines, such as IL-2, IL-9, IL-10, IL- 11, tumor necrosis factor-α, transforming growth factor-β1, and nerve growth factor, had no survival-promoting effect at 100 ng/mL. Preincubation of mast cells with SCF, IL-4, IL-5, or IL-6 for 24 hours during sensitization with IgE enhanced IgE/anti-IgE antibody-induced histamine release from mast cells, whereas IL-3 showed a negligible effect. Polymerase chain reaction amplification of α-chains of IL-3 receptor (R), IL-4 R, IL-5 R, and IL-6 R yielded products of the correct size predicted from the sequence of each receptor. The binding assay using ¹²⁵I-labeled IL-3 indicated that these mast cells bear receptors for IL-3. These findings suggest that IL-3, IL-4, IL-5, and IL-6, which are mainly produced by T-helper 2 lymphocytes, might regulate the functions of human mast cells in vivo via specific receptors in allergic reactions.