Transplant Immunology medical comic

This comic explains why the body treats a transplanted organ as an intruder. It defines the types of graft, explains histocompatibility and HLA, follows the three types of rejection and the pathways that drive them, and covers how matching, cross-matching and immunosuppression protect a graft — plus the twist of graft-versus-host disease.

For MBBS, NEET-PG, FMGE, NEXT and USMLE revision.

Transplant immunology: what the comic covers

High-yield points

Grafts are autografts (self), isografts (identical twin), allografts (same species) and xenografts (another species); orthotopic grafts go in the normal site, heterotopic grafts elsewhere.
Rejection is driven mainly by HLA (MHC) antigens; the Eichwald–Silmser effect describes rejection of male (Y-antigen) grafts by females in inbred animals.
Hyperacute rejection happens within minutes to hours from pre-formed antibodies (ABO or HLA) — prevented by cross-matching.
Acute rejection, over days to weeks, is mainly a cell-mediated attack led by CD8+ cytotoxic T cells.
Chronic rejection develops over months to years with progressive fibrosis and narrowing of graft vessels.
Recipient T cells recognise donor HLA directly on donor cells (direct pathway) or as peptides presented by their own cells (indirect pathway).
HLA typing and cross-matching reduce rejection; immunosuppressants such as calcineurin inhibitors, antiproliferatives and steroids keep it in check.
Graft-versus-host disease occurs when donor T cells (e.g. in a bone marrow transplant) attack the recipient's skin, gut and liver.

Quick questions

What causes hyperacute graft rejection?

Pre-formed antibodies in the recipient against donor ABO or HLA antigens. They bind the graft vessels within minutes to hours, activate complement and cause thrombosis. A pre-transplant cross-match prevents it.

Which cells drive acute graft rejection?

Mainly T cells, especially CD8+ cytotoxic T cells activated against donor HLA, helped by CD4+ T cells. Antibodies can also contribute.

What is graft-versus-host disease?

Immunocompetent donor T cells attack a recipient who cannot reject them, typically after bone marrow transplant. The skin, gut and liver are mainly affected.

Is this comic free to read?

The first pages are free to preview. Members read the full comic, and you can sign up free to read one comic in full.