Question

Which of the following statements about allelic exclusion is true?

a. An individual B cell is ensured to express Ig of multiple specificities after this process.
b. Functional genes are assembled by bringing together the different V region segments.
c. The mechanism used to create greater diversity in the B- or T-cell repertoire.
d. Ensures that only a single variable region of the light chain and one variable region of the heavy chain will be produced.
e. Allelic exclusion is expected to result in the generation of junctional diversity.

Answer 1

The statement regarding allelic exclusion that is true is that it ensures a single B cell expresses only one specific variable region for both the light and heavy chains of the antibody, not multiple specificities.

Step-by-step explanation:

Among the options provided, the true statement about allelic exclusion is (d) Ensures that only a single variable region of the light chain and one variable region of the heavy chain will be produced. Allelic exclusion is a process in which during B cell development, only one allele of the immunoglobulin gene is expressed while the other is silenced. This ensures that each B cell produces an antibody with a single specificity.

The genetic rearrangement process mentioned in the references forms an essential part of producing a diverse range of antibodies. In germ-line B cells, DNA recombinase initiates this process, randomly excising V and J segments from the light chain gene, and merging them to form a unique variable region capable of binding to different antigens. Further rearrangement involving V, D, and J segments of the heavy chain increases the diversity of antibodies that can be produced. However, allelic exclusion prevents the expression of multiple specificities within a single B cell.