Which factor would substantially interfere with a 3-color flow crossmatch?

The administration of anti-CD20 monoclonal antibodies can significantly interfere with a 3-color flow crossmatch due to the drug's effect on B cells, specifically targeting CD20+ B lymphocytes. This treatment reduces the population of B cells, which are involved in the antibody response against foreign antigens. Therefore, a flow crossmatch, which assesses the presence of donor-specific antibodies that could lead to graft rejection, may yield false-negative results, as the patient may not have a robust antibody response due to the depletion of these B cells.

This impact is crucial in the context of transplant immunology since the presence of specific antibodies against the anticipated donor could critically affect the success of the transplant. Knowing this interference allows for more informed decision-making regarding suitable candidates for transplant and tailoring additional monitoring or preparatory treatments to mitigate any risks.

Understanding this mechanism highlights the importance of considering patient history and recent treatments when interpreting crossmatch results, ensuring accurate assessments to optimize transplant outcomes.