Is acute rejection reversible?

Acute T-cell-mediated rejection is often reversible because it is detected early and responds to intensified immunosuppression, in contrast to chronic rejection, which reflects established structural damage.

How is acute rejection diagnosed?

It is suspected from a decline in graft function and confirmed by allograft biopsy, which is graded against standardized histological criteria such as the Banff classification.

Acute Rejection

Acute rejection is an immune attack on a transplanted organ that develops over days to months, classically driven by recipient T cells that recognize donor antigen and infiltrate the graft. It is the prototypical form of cellular allograft injury and, when detected, is the rejection type most amenable to reversal.

Definition

Acute rejection is graft injury occurring relatively early after transplantation, predominantly mediated by T cells infiltrating the graft (tubulitis and interstitial inflammation in the kidney), and characterized histologically and clinically by an inflammatory response to donor alloantigen that is often reversible with intensified immunosuppression.

Scope

This entry covers acute T-cell-mediated (cellular) rejection as a clinical and pathological entity: how it is recognized on allograft biopsy, how it is graded in classification systems such as Banff, and how it relates to acute antibody-mediated rejection. It is a reference description of the entity and its evidence base, not a treatment protocol.

Core questions

What histological features define acute T-cell-mediated rejection?
How is acute rejection distinguished from acute antibody-mediated rejection and from non-immune causes of early graft dysfunction?
How is severity graded, and why does grading matter for prognosis?

Key concepts

T-cell-mediated (cellular) rejection
Tubulitis and interstitial inflammation
Banff grading of acute rejection
Subclinical rejection
Allograft biopsy
Reversibility with augmented immunosuppression

Mechanisms

Acute cellular rejection is driven by recipient T cells that recognize donor histocompatibility antigens and become activated, proliferate, and traffic into the graft. CD8 cytotoxic T cells and CD4 helper T cells, with accompanying macrophages, infiltrate the interstitium and tubular or parenchymal epithelium, producing the tubulitis and interstitial inflammation that define the lesion in the kidney. Activation depends on antigen recognition plus co-stimulation and cytokine signalling, which is why these pathways are targeted by immunosuppression. A parallel acute process can be antibody-mediated, in which donor-specific antibodies injure graft microvasculature.

Clinical relevance

Acute rejection is identified through graft dysfunction and confirmed by biopsy graded against standardized criteria; recognizing it underlies the interpretation of transplant pathology and the design of immunosuppression studies. Subclinical rejection, found on protocol biopsy without overt dysfunction, illustrates that immune injury can precede functional change. This entry describes the entity and its evidence and does not provide individualized management guidance.

Epidemiology

The incidence of acute rejection in the first year after kidney transplantation has fallen substantially with modern immunosuppression, though episodes still occur and remain a risk factor for later graft injury, particularly when associated with donor-specific antibody.

History

Acute cellular rejection was the first and best-characterized form of rejection, central to early transplantation. The development of the Banff classification gave the field a reproducible vocabulary for grading acute lesions on biopsy, and successive revisions refined the separation of T-cell-mediated from antibody-mediated acute injury.

Debates

What is the significance of subclinical and borderline rejection?: Inflammation found on protocol biopsy without graft dysfunction, and borderline changes that fall short of diagnostic thresholds, are of uncertain prognostic weight, and how aggressively to treat them is debated within the classification literature.

Key figures

Brian Nankivell
Philip Halloran
Kim Solez
Mark Haas

Seminal works

nankivell-2010
solez-2008
haas-2018

Frequently asked questions

Is acute rejection reversible?: Acute T-cell-mediated rejection is often reversible because it is detected early and responds to intensified immunosuppression, in contrast to chronic rejection, which reflects established structural damage.
How is acute rejection diagnosed?: It is suspected from a decline in graft function and confirmed by allograft biopsy, which is graded against standardized histological criteria such as the Banff classification.