immune response, the function of SIRPα, CD22 and also PECAM-1, which is expressed on immune cells and endothelium and is involved in many signaling pathways, show that not all so called ITIM-bearing receptors can be considered to be inhibitory receptors. Several other proteins that are usually considered as stimulatory receptors contain ITIM-like sequences, e.g. IL-4. In contrast, the activating NK cell receptor NKp44 contains an ITIM, but this seems to be non-functional. Inhibitory receptors bearing ITIM Some of the important receptors bearing ITIM motifs are listed in the table below: My, myeloid; Hm, hematopoietic; NK, natural killer; EC, epithelial cells; DC, dendritic cells. (Modified according to) ITIMs in immunotherapy On the basis of the inhibitory effects of FcγRIIB, a lot of prototypic molecules was constructed and used for developing new therapeutic approaches of allergies. A genetically engineered molecule consisting of a human IgG1 Fc fragment fused to a human IgE Fc fragment was first reported to inhibit IgE-induced human mast cell and basophil activation. In selected human malignancies such as acute myeloid leukemia, allogeneic hematopoietic cell transplantations have shown that the development of donor NK cells in recipient patients lacking donor KIR ligands can lead to improved engraftment and post-transplant survival by boosting graft-versus-leukemia effect in the absence of graft-versus-host disease. References Immune system