Abstract: The invention provides a pharmaceutical composition including a cytokine and a peptide comprising at least a portion of a chemokine receptor or a c_protein coupled receptor. The pharmaceutical composition of the invention may be used for altering immune system functioning, for example, to treat an immune system disorder, such as an autoimmune disease, multiple sclerosis, transplant rejection, psoriasis and asthma. The invention also provides peptides that may be used in the pharmaceutical composition and a method for preparing the pharmaceutical composition of the invention. The invention further provides a method for to treating an immune system disorder, such as an autoimmune disease, multiple sclerosis, transplant rejection, and psoriasis asthma.