Question

Each B lymphocyte makes antibody of one single specificity that is fixed by the nature of gene rearrangements. During the lifetime of an individual cell, however, it can switch to make a different class of antibody, while retaining the same antigenic specificity. This is known as class or isotype switch. Class switching occurs in mature B cells and is dependent on antigenic stimulation of the cell and the presence of factors released by T cells. These factors are known as?

Cytokines
Immunoglobulins
Caspases
RANTES
Selectins

Answer 1

The factors released by T cells that induce B cell class switching are cytokines. This process allows B cells to change the classes of antibodies they produce without altering their specificity for a particular antigen.

Step-by-step explanation:

B lymphocytes, or B cells, produce antibodies with a specificity fixed by gene rearrangements. When an antigen stimulates these cells, and in the presence of factors released by T cells, B cells can undergo a process known as class switching or isotype switching. This enables them to switch antibody classes (e.g., IgM to IgG, IgA, or IgE) while keeping the same antigenic specificity. The factors released by T cells that facilitate this process are known as cytokines.

Different classes of antibodies, such as IgM, IgG, IgA, IgE, and IgD, have unique constant domains that define their class but share the same variable domains that determine antigen specificity. The recombination of these gene segments during class switching affects only the constant region, allowing the new antibody to retain the original epitope binding capacity.

B cells initially produce pentameric IgM, which can switch to other antibody classes due to cytokines from T helper 2 (Th2) cells. This conversion provides a variety of immune responses to the same antigen, enhancing the body's capability to fight infections effectively.