What forms of graft-vs.-host disease are there?

Graft-versus-host disease (GVHD) can be classified into two main forms based on the time of onset after hematopoietic stem cell transplantation (HSCT):

1. Acute GVHD:

- Develops within the first 100 days after HSCT.

- It typically affects the skin, gastrointestinal tract, and liver.

- Acute GVHD can be mild, moderate, or severe, with severe cases being life-threatening.

2. Chronic GVHD:

- Develops more than 100 days after HSCT.

- It can affect almost any organ or tissue in the body, but commonly involves the skin, mucous membranes, liver, lungs, and eyes.

- Chronic GVHD can be more insidious and difficult to treat compared to acute GVHD.

In addition to these two main forms, there is also a rare variant known as hyperacute GVHD. Hyperacute GVHD occurs within the first 24-72 hours after HSCT and is often associated with a very high mortality rate.

It's worth noting that the frequency and severity of GVHD depend on various factors, including the type of HSCT (allogeneic vs. autologous), the degree of HLA matching between the donor and recipient, the conditioning regimen used before transplantation, and the recipient's immune status.