C4d Staining of Cardiac Allografts Correlates with Alloantibody

 

R.N. Smith, N. Brousaides, S. Saidman, and A.B. Collins

Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114-2696

 

C4d staining of kidney allografts correlates well with the in vivo alloantibody deposition in kidney allografts, thereby identifying those patients at risk for antibody mediated rejections. To try to identify those patients with cardiac allograft antibody deposition and to investigate the role that C4d staining might play in the diagnosis of cardiac allografts, we correlated C4d staining in cardiac allograft biopsies with anti-donor specific alloantibodies.

 

We assayed a large number of frozen tissues from cardiac allograft biopsies and autopsies, both retrospectively and prospectively, for C4d by three step indirect immunofluorescence. Of these we were able to identify 75 tissue samples from 36 patients with synchronous (within one month of biopsy) serum samples also assayed for alloantibody. Of these 8 patients were identified with antibodies with 18 tissue samples.  The criterion for positive staining is diffuse capillary wall staining, similar to that in the kidney. Antibody positive and negative groups had similar mean intervals after transplant, 147 and 182 days respectively, P=0.8. 16 of these 18 (89%) were positive for C4d. Of 57 tissue samples paired with serum samples without alloantibody, 56 were C4d negative (98%, P<0.001). 20 biopsies from patients with non-transplant cardiac diseases were negative. Staining did not correlate with post implant ischemic injury P=0.4 or OKT3 therapy.

 

Initially performed on frozen section, C4d staining can now be done on paraffin sections. We were able repeat on paraffin 34 of the 75 frozen biopsies. The criterion for positive C4d staining is diffuse capillary wall staining. All eleven positive frozen biopsies were positive on paraffin. Of 23 biopsies negative on frozen, one stained on paraffin, P<0.001.

  

To test additional controls, we stained paraffin sections on 43 non-transplant medical cardiac biopsies and compared these to 113 transplant biopsies. Of 43 non-transplant biopsies, only two stained for C4d, (5%). Of 113 transplant biopsies, 27 stained for C4d, (24%), P<0.001. If we exclude from the transplant group, those patients known to have antibodies, then only 10 of 95 transplant biopsies are C4d positive, (11%), P= 0.2.

 

We conclude that C4d staining on both frozen and paraffin embedded tissue correlates well with serum alloantibody and that C4d staining in cardiac allografts likely represent in vivo deposition.  

 

 

 

 

C4d Staining of Cardiac Allografts Correlates with Alloantibody

 

R.N. Smith, N. Brousaides, S. Saidman, and A.B. Collins

Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114-2696

 

 

Rex Neal Smith, MD

Department of Pathology, Warren 501D

Massachusetts General Hospital

Boston, MA  02114-2696

614-726-1835

smith.rex@mgh.harvard.edu