Medical Laboratory Scientist (MLS) ASCP Practice Exam

A 3+ blood reaction grade indicates a moderate level of agglutination. This level is characterized by several large clumps formed during the agglutination process, which suggests that a significant number of red blood cells are clumping together due to the presence of antibodies reacting with antigens on the surface of those cells.

The presence of clear supernatant further supports a 3+ grade, as it suggests that the unagglutinated cells are not significantly present in the solution, which can happen when large clumps are formed, causing remaining cells and plasma to clear out. This visual representation is quite distinct compared to lower grades of agglutination, where smaller clumps might be observed and could still leave some degree of red coloration in the supernatant.

Thus, in evaluating the choices, the correct manifestation for a 3+ reaction would be the formation of several large clumps accompanied by a clear supernatant, illustrating the concept of moderate to strong agglutination in blood typing or compatibility testing.