T helper frequencies in peripheral blood reflect donor-directed reactivity in the graft after clinical heart transplantation

Abstract

SUMMARYWe describe the usefulness of a fast (48-h) limiting dilution assay (LDA) for the enumeration of human alloreactive helper T lymphocytes (HTL) in the peripheral blood, in relation to histologically de®ned rejection grades after heart transplantation. HTL frequencies (HTLf) in pretransplant samples varied from patient to patient, ranging from 106 to 625 HTL/10 6 peripheral blood mononuclear cells (PBMC). In the ®rst week after heart transplantation (HTx), when immunosuppression was instituted, HTLf were signi®cant lower (range 30±190 HTL/10 6 ). The level of HTL in the ®rst week after HTx when rejection grade was 0 or 1A (ISHLT score) was considered to be the baseline frequency. This frequency did not correlate with the number of subsequent rejection episodes. During rejection (grade 3), donor-speci®c HTLf were increased above their baseline frequencies (P 0´01). Expressed as percentage of baseline frequencies, HTLf increased signi®cantly during acute rejection (AR) compared with 1±2 weeks before rejection (P 0´003). The increase was speci®c, since viral infections did not result in a rise of donorspeci®c HTL, while also HTLf speci®c for third party HLA antigens were not elevated during rejection. Monitoring HTLf in peripheral blood with a shortened (48-h) assay may serve as a non-invasive method for detecting intragraft immunological reactivity. Demonstrating absence of donor-speci®c reactivity may limit the number of invasive endomyocardial biopsy (EMB) procedures and allow tapering of immunosuppressive treatment.

Cd69 Expression on Peripheral Cd8 T Cells Correlates With Acute Rejection in Renal Transplant Recipients

“…Furthermore, they were able to differentiate delayed graft function resulting from nonimmunologic causes from acute rejection (23). Similarly, when peripheral blood lymphocytes from cardiac allograft recipients were analyzed by limiting dilution analysis, increased frequencies of donor-specific T helper cells were found in patients with acute rejection (25). One potential drawback of these studies is that they are labor intensive and require a significant period of time for completion.…”

Donor-specific Cytotoxic Hyporesponsiveness Associated With High Interleukin-10 Messenger RNA Expression in Cardiac Allograft Patients

“…Several studies have found lower HTLp and CTLp frequencies to donor antigens than to third-party antigens in renal, cardiac, and lung allograft recipients some years after transplantation. 6,8,9,29,30 Because of limited patient and donor material, we focused on the cytotoxic cell.…”

Noninvasive methods to assess the risk of kidney transplant rejection

“…In several studies, a direct correlation between the frequencies of precursors among peripheral blood cells and histologically defined rejection in heart or kidney transplant recipients was detected [18,19]. Although results obtained with LDA may predict short-term outcomes and help in customizing immunosuppressive therapy, the complexity and required labor intensity for reproducible assay performance may limit the broad applicability of LDA as a clinical biomarker of alloreactivity.…”