Humoral theory of transplantation

Predicting kidney graft failure by HLA antibodies: a prospective trial

HLA antibodies have been shown to be associated with late graft loss of organ transplants in prior studies. Recently they were even shown to appear years BEFORE rejection. (1) An international cooperative study of 4763 patients from 36 centers was undertaken to determine the frequency of HLA antibodies in patients with functional transplants. The overall frequency of HLA antibodies among kidney transplant recipients was 20.9%; 19.3% in the liver, 22.8% in the heart, and 14.2% in the lung. Patients treated with CsA-MMF had significantly lower antibodies (9.8%) than those treated with CsA-Aza (18.1%) (0.00008). (2) Second, a prospective trial was performed in 23 kidney transplant centers to determine whether HLA antibodies could predict failures within 1 year. Among the 2278 patients followed up, 91 grafts failed and 34 patients died. Of 500 patients who had HLA antibodies, 6.6% failed compared with 3.3% among 1778 patients without antibodies (p = 0.0007). Among 244 patients who made de novo antibodies, 8.6% failed compared with 3.0% failures among 1421 patients who did not make antibodies (p = 0.00003). Death occurred in 1.5% of patients and was not associated with antibodies. Thus, after 1 year in this prospective trial, patients with HLA antibodies had graft failure at a significantly higher rate than those without antibodies.

Allograft arteriopathy

Allograft arteriopathy is a vascular intimal proliferative process that occurs in all solid organ transplants and stands as the single most significant obstacle to successful long-term solid organ transplantation; it shares a number of pathologic features with restenosis lesions and atherosclerosis. This article will review some of the newer developments in our understanding of the immunological and vascular biology underpinnings of the disease, including the roles played by cytokine and chemokine mediators in recruiting and activating both inflammatory cells, as well as smooth muscle cell precursors.

The role of B cells and alloantibody in the host response to human organ allografts

Some human organ transplants deteriorate slowly over a period of years, often developing characteristic syndromes: transplant glomerulopathy (TG) in kidneys, bronchiolitis obliterans in lungs, and coronary artery disease in hearts. In the past, we attributed late graft deterioration to "chronic rejection", a distinct but mysterious immunologic process different from conventional rejection. However, it is likely that much of chronic rejection is explained by conventional T-cell-mediated rejection (TMR), antibody-mediated rejection (AMR), and other insults. Recently, criteria have emerged to now permit us to diagnose AMR in kidney transplants, particularly C4d deposition in peritubular capillaries and circulating antibody against donor human leukocyte antigens (HLA). Some cases with AMR develop TG, although the relationship of TG to AMR is complex. Thus, a specific diagnosis of AMR in kidney can now be made, based on graft damage, C4d deposition, and donor-specific alloantibodies. Criteria for AMR in other organs must be defined. Not all late rejections are AMR; some deteriorating organs probably have smoldering TMR. The diagnosis of late ongoing AMR raises the possibility of treatment to suppress the alloantibody, but efficacy of the available treatments requires further study.