Value of Immunohistochemistry in Comparison to Immofluorescence for Detecting Immune Deposits in renal Biopsy

Evaluation and classification of many renal lesions particularly glomerular diseases are only on the basis of renal biopsy. The clinician's request from the histopathologist is a timely and accurate diagnosis of renal damage which in addition to light microscopy is dependent on the assessment of immune deposits in renal biopsy and verification of immune deposits in Electron microscopy. IF(Immunofluorescence) method which is simple and rapid is gold standard. Due to limitation of this method, received paraffin blocks can be used for detection of immune deposits in IHC(Immunohistochemistry). Other advantages of IHC method include: permanence of stained slides, possibility of morphologic assessment of the lesion and correlation of deposit location and glomerular anatomy. Undoubtedly IHC method has disadvantages including complexity of the technique in comparison to IF, background staining, few number of available antibodies as well as being time consuming. In this comparative study renal biopsy specimens from Hasheminejad hospital, which were reported according to IF and light microscopy, were separated and then IHC with IgG, IgM, IgA, C3 and C1q, was performed on these blocks. IHC was based on Immunoperoxidase(IP) method. Presence, kind and location of deposits were recorded by light microscopy. At the same time, H&E, silver, trichrome and PAS stained slides were evaluated. Immune deposits similar to IF were detected by IHC method in 20 out of 26 samples. IHC method couldnot detect visible immune deposits in 4 cases including amyloidosis, MGN(1 case) and IgA nephropathy(1 case). Therefore, sensitivity, specificity, accuracy, positive and negative predictive values of IHC method in diagnosis of renal biopsy specimens is 91%, 100%, 92%, 100% and 65%, respectively. It seems that due to high rate of sensitivity, specificity and accuracy, IHC method which is used by experienced technical staff, can be used as an alternative method for IF when there are no glomeruli in IF specimen or there is difficulty in taking a renal biopsy. Thus according to these finding, the renal pathological lab, should be equipped with both methods, and accountable pathologist, should recognize which method to be used on the basis of clinical state of the patient and adequacy of received specimen.