A number of diseases, including Alzheimer's disease,18 systemic lupus erythematosus19,20 and rheumatoid arthritis,21 have been associated with changes in the phenotypic and functional characteristics of monocyte-derived DCs (i.e. CD14+ monocytes cultured in the presence of GM-CSF and IL-4 alone). Here, IL4 is linked to early-onset autosomal dominant Alzheimer disease.