Pruritic forms of inflammatory skin diseases, or itchy skin diseases, have been found to have elevated levels of IL-31 mRNA in patient biopsies. Analysis of the tissue distribution of the IL-31 receptor complex found that IL-31RA is abundant in dorsal root ganglia of different human tissues. Dorsal root ganglia is where the cell bodies of primary sensory neurons reside. Dorsal root ganglia are also believed to be where the "itch" sensation originates. These findings support the elevated levels of IL-31 in skin biopsies of pruritic skin diseases.