INHIBITORY EFFECT OF INTERLEUKIN-2 ON HISTAMINE-RELEASE FROM RAT MAST-CELLS

Interleukin-2 (IL-2) inhibited histamine release from rat mast cells i nduced by compound 48/80 in a concentration-dependent manner. The inhi bitory effect of IL-2 on histamine release was also dependent on the l ength of the incubation period; the maximum inhibition was achieved at 8h after IL-2 addition. Furthermore, IL-2 inhibited not only IF, prod uction but also Ca-45 uptake in mast cells stimulated by compound 48/8 0. Since IL-2 enhanced [H-3]-leucine uptake into mast cells, this sugg ests that protein synthesis may be related in some way with the inhibi tion of histamine release. IL-2 treatment augmented the synthesis of a protein having a molecular weight of approximately 35 kDa. From Weste rn blotting analysis, it became clear that the production of lipocorti n-I was augmented in rat mast cells by IL-2 treatment. The present stu dy shows that IL-2 induces the synthesis of lipocortin-I in mast cells and that lipocortin-I may play some role in inhibiting histamine rele ase from mast cells.