Isotype control antibody is a kind of antibody which has the same isotype as a primary antibody but with no relevant specificity to the target antigen. It is usually used as a negative control in the experiment. In other words, isotype controls work as a substitute for antibodies and indicates whether there is unspecific binding of immunoglobulins in your probe.
In Creative Diagnostics, Many isotype control products are available to be chosen. You can select purified antibodies from the same isotype and species as the primary antibody.