Which reaction can occur if AHG is added too late in antiglobulin testing?

In antiglobulin testing, the addition of antihuman globulin (AHG) is crucial for detecting antibodies or complement proteins that may be bound to red blood cells. When AHG is added too late, it may not adequately bind to the target antigens present on the cells, leading to a scenario where bound antibodies are not properly visualized.

A false negative reaction occurs when the test fails to show a positive result even though the antibodies are present. This can be due to inadequate reaction time between the red cells and the AHG. The delay in adding AHG means that the antigen-antibody complexes may not form effectively, leading to a failure in detecting the sensitization of red blood cells, resulting in a missed positive reaction.

Conversely, increased false positive reactions, incorrect blood group determination, and hemolysis of control cells are less directly associated with the timing of AHG addition. The focus here lies in the failure to demonstrate the expected positive reaction, which aligns with a false negative result. Thus, proper timing of the AHG addition is crucial to ensure accurate test outcomes in antiglobulin testing.