What is the recommended timing for the next anti-A titer assessment in a patient with a recipient blood type O and donor blood type A, who underwent plasma exchange prior to ABO incompatible bone marrow transplant (Bone Marrow Transplantation, BMT) and had a return of anti-A with a titer of 128 on day two post-transplant?

From the Research

The next anti-A titer should be performed on day 3 following transplant. In ABO incompatible bone marrow transplants, frequent monitoring of antibody titers is essential, particularly in the early post-transplant period. With a recipient blood type O and donor type A, the recipient's anti-A antibodies can cause hemolysis of donor cells. Although the titer has improved to 1:128 after plasma exchange, this level is still clinically significant and requires continued monitoring.

Key Considerations

• Daily titer measurements are typically recommended for the first week post-transplant when titers remain elevated above 1:16, with subsequent frequency determined by the trend in titer levels 1.
• If the titer continues to decrease, monitoring can be extended to every 2-3 days, but if it increases, more aggressive plasma exchange may be needed to prevent hemolytic complications.
• The goal is to maintain titers below 1:16, which is generally considered safe for engraftment without significant hemolysis risk.

Clinical Evidence

• A study published in 2011 compared the clinical outcome between high and low baseline anti-ABO antibody titers in ABO-incompatible kidney transplantation, and found that ABO-incompatible kidney transplantation can be safely performed even in patients with a high baseline anti-ABO antibody titer, but the risk for infection and bleeding should be considered before transplantation 1.
• Another study published in 2004 presented the Mayo Clinic experience with ABO-incompatible transplants from living donors, and found that pre-transplant plasma exchange conditioning combined with other immunosuppressives can be used to prepare patients for ABO-incompatible kidney transplantation from living donors, but antibody-mediated rejection post-transplant is a common occurrence and allograft survival may be reduced 2.

Monitoring and Management

• The patient's anti-A antibody titer should be closely monitored, and plasma exchange should be performed as needed to maintain titers below 1:16.
• The patient should be closely monitored for signs of hemolysis, and more aggressive plasma exchange may be needed if the titer increases or if there are signs of hemolytic complications.
• The use of immunosuppressive therapy, such as rituximab, may also be considered to help reduce the risk of antibody-mediated rejection 3, 4.