In the process of identifying an antibody, which antibody is most likely present if there is no reactivity after incubation at 37C?

When identifying antibodies in blood bank practice, the temperature at which the incubation occurs can provide insights into the characteristics of the antibodies present. The scenario described indicates that there is no reactivity after incubation at 37°C.

Anti-Le^a (Lewis antibody) is often associated with a weak or absent response at body temperature, particularly in comparison to other antibodies. This antibody is typically IgM, which means that it generally reacts at cooler temperatures (like room temperature) rather than at the warmer 37°C. This characteristic is what makes it likely that anti-Le^a would be identified when no reactivity is observed at 37°C.

In contrast, other antibodies listed, such as anti-C, are more likely to show reactivity at the higher incubation temperatures due to their IgG nature. Similarly, anti-Fy^a and anti-P1 typically demonstrate reactivity at physiological temperatures as well.

Thus, the absence of reactivity at 37°C strongly supports the presence of anti-Le^a, as it aligns with its known behavior of exhibiting weaker reactions at body temperature.