Provided herein are methods for activating an immune cell in a subject. In some embodiments, the methods comprise passing an immune cell from a subject through an immune modulating chamber comprising a tumor cell, thereby activating the immune cell, and returning the activated immune cell to the subject. In some embodiments, the methods further comprise isolating an immune cell-containing portion of a sample and passing the immune cell-containing portion through the immune modulating chamber. Methods of treating cancer and methods of inducing an immune response against a tumor are also provided herein.