Test Catalog

Test ID: CO4D    
Complement 4d (C4d, Comp 4d) Immunostain, Technical Component Only

Useful For Suggests clinical disorders or settings where the test may be helpful

Aids in the identification of antibody-mediated transplant rejection

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Complement 4d (C4d) is a split product resulting from complement activation. The deposition of C4d on the walls of peritubular capillaries in kidney allografts or capillaries in cardiac allografts has been associated with antibody-mediated transplant rejection.

Interpretation Provides information to assist in interpretation of the test results

This test includes only technical performance of the stain (no pathologist interpretation is performed). Mayo Clinic cannot provide an interpretation of tech only stains outside the context of a pathology consultation. If an interpretation is needed, refer to PATHC / Pathology Consultation for a full diagnostic evaluation or second opinion of the case. All material associated with the case is required. Additional specific stains may be requested as part of the pathology consultation, and will be performed as necessary at the discretion of the Mayo pathologist.


The positive and negative controls are verified as showing appropriate immunoreactivity and documentation is retained at Mayo Clinic Rochester. If a control tissue is not included on the slide, a scanned image of the relevant quality control tissue is available upon request. Contact 855-516-8404.


Interpretation of this test should be performed in the context of the patient's clinical history and other diagnostic tests by a qualified pathologist.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Age of a cut paraffin section can affect immunoreactivity. Stability thresholds vary widely among published literature and are antigen-dependent. Best practice is for paraffin sections to be cut fresh.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Fedson SE, Daniel SS, Husain AN: Immunohistochemistry staining of C4d to diagnose antibody-mediated rejection in cardiac transplantation. The Journal of Heart and Lung Transplantation 2008;27(4):372-379

2. Magro CM, Dyrsen ME: The use of C3d and C4d immunohistochemistry on formalin-fixed tissue as a diagnostic adjunct in the assessment of inflammatory skin disease. J AM Acad Dermatol 2008;59(5):822-833

3. Roden AC, Scott JP, Jenkins SM, Aubry MC: C4d by immunofluorescence and immunohistochemistry in routine lung allograft biopsies. The Journal of Heart and Lung Transplantation 2013;32(45):519-520