Efficient immunotherapy can be accomplished by expanding T cells outside the body using single walled carbon nanotube (SWNT) bundles presenting antibody stimulus. Owing to the large surface area of these bundles, which can reach 1560 m2/g, T cell stimulating antibodies such as anti-CD3, can be presented at high local concentrations inducing potent activation of T cells. We show that anti-CD3 adsorbed onto SWNT bundles stimulate cells more effectively than equivalent concentrations of soluble anti-CD3. Stimulation by antibody-adsorbed onto SWNT is significantly more than other high surface area materials (activated carbon, polystyrene and C60 nanoparticles), suggesting unique properties of SWNT bundles in stimuli presentation. We demonstrate the surface area tunability of these bundles by chemical treatment and its effect on antibody adsorption and subsequent T cell activation. In addition, the T cell response varied with the concentration of SWNT in a dose dependent manner. Antibody stimuli adsorbed onto SWNT bundles represent a novel paradigm for efficient activation of lymphocytes, useful for basic science applications and clinical immunotherapy.