Which laboratory test result would likely be negative in a patient experiencing TRALI?

In the context of a patient experiencing Transfusion-Related Acute Lung Injury (TRALI), the Direct Antiglobulin Test (DAT) would likely be negative. TRALI is an acute immune-mediated reaction typically caused by antibodies in the donor blood that react with recipient leukocytes, leading to pulmonary inflammation and edema.

In TRALI cases, the antibodies involved are usually directed against HLA or neutrophil antigens and do not result in the formation of red blood cell antibodies, which is what the DAT tests for. As a result, the DAT would not show evidence of sensitization with red blood cells, hence yielding a negative result.

The other tests, such as crossmatch, type and screen, and antibody screening, are meant to identify compatibility and potential antibodies against red blood cells. These tests focus on red blood cell antigens and donor-receiver compatibility, which are not the direct cause of TRALI. In patients suffering from TRALI, there may be a presence of donor antibodies directed towards leukocytes rather than the red blood cells that these tests would typically evaluate, reinforcing why the DAT would not indicate any positive results in this scenario.