Question

Graft versus host disease occurs when

• A. Host attacks graft tissue
• B. Graft immune cells attack host tissue
• C. Both graft and host are inactive
• D. Only antibodies are involved

Hint:

Remember the difference: \[ \boxed{ \text{Host vs Graft} = \text{Transplant Rejection} } \] \[ \boxed{ \text{Graft vs Host} = \text{Donor T Cells Attack Recipient} } \] GVHD is commonly seen after allogeneic bone marrow transplantation.

Answer 1

The Correct Option is B

Concept: Graft-versus-Host Disease (GVHD) is an immune disorder that may occur after bone marrow or stem cell transplantation. It develops when immunocompetent T-lymphocytes present in the donated graft recognize the recipient's tissues as foreign and mount an immune response against them. GVHD commonly affects the skin, liver, gastrointestinal tract, and other organs.

Step 1: Understand Graft-versus-Host Disease.
Normally, transplant rejection occurs when the recipient's immune system attacks the transplanted tissue. However, in GVHD the opposite occurs: \[ \boxed{ \text{Donor Immune Cells} \Longrightarrow \text{Attack Recipient (Host) Tissues} } \] This condition is mainly associated with allogeneic bone marrow transplantation.

Step 2: Mechanism of GVHD.
The disease develops when:
• Donor T-lymphocytes remain active.
• Recipient tissues possess different HLA antigens.
• Donor immune cells recognize host tissues as foreign.
• Cytotoxic immune responses damage host organs. Commonly affected organs include:
• Skin
• Liver
• Intestine
• Bone marrow

Step 3: Eliminate incorrect options.

• Host attacking graft tissue describes transplant rejection, not GVHD.
• GVHD specifically involves donor immune cells attacking the recipient.
• Both graft and host are not inactive.
• Antibodies alone are not responsible; donor T cells play the major role. Final Answer: \[ \boxed{Option (B) is correct \]