Question

a patient has anti-le\\(^a\\) antibodies. ficin treated le(a+b-) cells would likely demonstrate:

weaker reactivity with the patients antibody.
enhanced reactivity with the patients antibody.
elution of the patients antibody.
no reactivity with the patients antibody.

Explanation:

Identify the antibody and antigen system

The patient has anti-\(\text{Le}^\text{a}\) antibodies, which belong to the Lewis blood group system. The target red blood cells are phenotyped as \(\text{Le(a+b-)}\), meaning they express the \(\text{Le}^\text{a}\) antigen on their surface.

Determine the effect of ficin treatment

Ficin is a proteolytic enzyme used in immunohematology to treat red blood cells. Proteolytic enzymes cleave specific glycoproteins on the red cell membrane, which can either destroy, enhance, or have no effect on various blood group antigens.

Analyze enzyme effects on Lewis antigens

The Lewis antigens (\(\text{Le}^\text{a}\) and \(\text{Le}^\text{b}\)) are adsorbed onto the red cell membrane from the plasma rather than being integral membrane glycoproteins. Treatment of red blood cells with proteolytic enzymes like ficin or papain denatures other surface structures, reducing steric hindrance and negative surface charge (sialic acid). This enhances the accessibility of Lewis antigens to their corresponding antibodies. Therefore, ficin treatment enhances reactivity.

Evaluate the given options

• weaker reactivity: Incorrect, as enzyme treatment does not depress Lewis antigens.
• enhanced reactivity: Correct, because ficin treatment enhances the reactivity of Lewis antibodies.
• elution of the patient's antibody: Incorrect, elution is a process to remove bound antibodies, not a direct result of testing treated cells.
• no reactivity: Incorrect, Lewis antigens are not destroyed by ficin.

Answer:

• weaker reactivity with the patient's antibody.
• enhanced reactivity with the patient's antibody. (Correct answer)
• elution of the patient's antibody.
• no reactivity with the patient's antibody.