What sample type is best for detecting complement-dependent antibodies?

The best sample type for detecting complement-dependent antibodies is serum stored at 4°C for no longer than 48 hours.

Serum is preferred over plasma because it lacks clotting factors that could interfere with the complement activity. Additionally, storing serum at 4°C maintains the stability of complement proteins and ensures that any complement-dependent antibodies remain functional for testing purposes. The time limit of 48 hours is critical as it helps to prevent degradation of the serum components, which could lead to false-negative results due to diminished antibody or complement activity.

While plasma stored at 4°C can preserve some functionality, it is generally less favorable for this specific test due to the presence of clotting factors and potential interference from the anticoagulant used. Other options, such as storing samples at room temperature or heating serum, could significantly alter the composition and functionality of the antibodies and complement, making them unsuitable for accurate detection of complement-dependent antibodies.