61-P

Abstract

Antibody mediated rejection (AMR) is a significant source of morbidity and mortality in cardiac transplant recipients. Because antibody mediated rejection is known to use the complement pathway, assessment of antibodies that fix complement, such as C1q may show promise here as a quantitative marker of the degree of severity of disease, as well as response to treatment. This was a retrospective case study of 5 patients with biopsy proven AMR. Charts were analyzed for rejection episodes, echocardiographic data, and treatment for AMR. AMR was determined from C4d and CD68 stained sections. Final clinical diagnosis included evidence of allograft dysfunction, HLA donor specific antibody (DSA) and C1q DSA. The 5 cases are graphically presented with time points for biopsy evaluation, echocardiogram, HLA and C1q antibody testing, and treatment. The results of this study indicate that measuring donor specific C1q antibodies may be useful in assessing the severity of AMR as well as the response to treatment. Evaluation of these cases indicate pursuing a larger study is a worthwhile endeavor to further investigate the role of C1q testing as an independent and quantifiable marker for AMR. C1q antibody evaluation may help reduce the frequency of routine surveillance biopsy in cardiac transplant patients, leading to a less invasive method of assessing for rejection. In addition, it can be used to appropriately guide treatment. Studies with longer-term follow-up may help to determine how long after treatment the antibodies will take to completely clear, as more information is needed on how to properly interpret elevated levels of C1q antibodies post-treatment. Correlation of post-treatment levels of C1q with the clinical status of the patient, as well as biopsy data, will help to determine if measurement of C1q can help determine if a particular treatment was a success or a failure. Overall, this study is a good starting point for the assessment of C1q HLA DSA as a marker for AMR.