Which statement about Rh antibodies is true?

• A. They react better at 4C
• B. They react stronger at 37C than at 22C
• C. They react equally at all temperatures
• D. They react only at room temperature

Answer: (D)

Rh antibodies are typically IgG alloantibodies whose ability to bind red cell antigens is strongly temperature-dependent. They react best at body temperature (around 37°C) and are usually detected using antiglobulin-based methods performed at that temperature. At room temperature (about 22°C) their reactivity is weaker and may be missed, and at 4°C they are generally not reactive. Because of this, the statement that they react stronger at 37°C than at 22°C is the correct description. They do not react only at room temperature, nor do they react equally at all temperatures.