What outcome indicates a negative result in a complement fixation test?

What outcome indicates a negative result in a complement fixation test?

• A. Hemagglutination
• B. Absence of hemagglutination
• C. Hemolysis
• D. Absence of hemolysis

Answer: (C)

In a complement fixation test, a negative result is indicated by the presence of hemolysis. This test evaluates the function of the complement system in the serum and its ability to lyse, or break down, red blood cells. When a specific antibody is present in the serum, the antibody-antigen complex is formed, and this activates the complement system. If the complement has been fixed to the antigen-antibody complex, there will be no free complement available to cause hemolysis of the red blood cells. Thus, a lack of hemolysis (as seen in a positive result) indicates that complement has been fixed, leading to no lysis of the cells. In contrast, if hemolysis occurs, it confirms that there was no fixation of complement because it remains free in the system and is available to cause the destruction of red blood cells. Therefore, the presence of hemolysis is indicative of a negative result in the context of this test.

In a complement fixation test, a negative result is indicated by the presence of hemolysis. This test evaluates the function of the complement system in the serum and its ability to lyse, or break down, red blood cells.

When a specific antibody is present in the serum, the antibody-antigen complex is formed, and this activates the complement system. If the complement has been fixed to the antigen-antibody complex, there will be no free complement available to cause hemolysis of the red blood cells. Thus, a lack of hemolysis (as seen in a positive result) indicates that complement has been fixed, leading to no lysis of the cells.

In contrast, if hemolysis occurs, it confirms that there was no fixation of complement because it remains free in the system and is available to cause the destruction of red blood cells. Therefore, the presence of hemolysis is indicative of a negative result in the context of this test.