A method of immunomodulating the T cell response in Staphylococcal bacteria is provided wherein an effective amount of the Map protein from Staphylococcus aureus is administered to a host to prevent or suppress the T cell response. The present method may be utilized with either the Map protein or an effective subdomain or fragment thereof such as the Map 10 or Map 19 protein. The present invention is advantageous in that suppression or prevention of the T cell response in a host can prevent or ameliorate a wide variety of the pathogenic conditions such as T cell lymphoproliferative disease and toxic shock syndrome wherein the overstimulation of T cells needs to be suppressed or modulated.