Immunopathology is a branch of medicine that deals with immune responses associated with disease. It includes the study of the pathology of an organism, organ system, or disease with respect to the immune system, immunity, and immune responses.

It is a subspecialty of Clinical Pathology which consists in analysis of body fluids for detection of immune system diseases.

(Source : Medline Plus : Medical Dictionary)

In biology, it refers to damage caused to an organism by its own immune response, as a result of an infection.