Abstract: The variants of human ciliary neutrophic factor (hCNTF) according to the present invention are characterized by substitution of phenylalanine 152 and/or lysine 155 with alanine. These variants have biological properties that render them important as the active principles of drugs for the treatment of diseases and pathologies involving the nervous system or other pathologies involving cells responding to the CNTF. FIG. 2 shows the results of simulation of haptoglobin secretion from HepG2 cells by CNTF and the variants described in the invention.