Classification of cytokines according to the receptor code.

A simple classification of cytokines is presented. It is based on voluminous information available from published papers of many outstanding researchers of the cytokines and their receptors and/or summarized by experts in this field. The cytokines are divided into 7 families according to their receptor code. Such arrangement of apparently different cytokines may explain the biological significance of pleiotropy and redundancy. Furthermore, it may stimulate the development of the comprehensive classification of cytokines together with classical hormones, neuromediators, neuromodulators and related substances that participate in complex biological communication system.