The present invention relates to the use of alpha (2) macroglobulin complexes isolated from the serum of a mammal. The invention also relates to methods for making such complexes and compositions comprising alpha (2) macroglobulin complexes, isolated from the serum of a mammal, wherein such compositions are used in methods for the treatment and prevention of cancer and infectious disease. The invention also relates to methods for treating and preventing cancer and infectious disease using such complexes comprising, isolated from the serum of a mammal. The invention also encompasses methods for production of alpha (2) macroglobulin complexes.