Question

Define “ligand” and briefly describe how it relates to this case study ( CD 40 ligand deficiency).

Answer 1

Ans. Ligand is a molecule which binds to another molecule, as a neurotransmitter or a hormone which binds to a receptor. Ligand travels through fluids i.e within blood, tissue or cell and at high concentration they reach to a protein, which can be a receptor or channel and binds to them. When the ligand is binded to the protein it goes under conformational change which will trigger many actions such as chemical pathway or release of another ligand or to carry the message to other receptors.

Here in the CD 40 ligand deficiency cellular and humoral immunity is affected. It is inheritted as a X-linked recssive disease and mostly seen in males. CD40 is a co-stimulatory receptor on B-cell that when get bounded to the CD40 ligand, sends signal to the B-cell receptor. When there is a deficiency in CD40 it leads to defective T-cell interaction with B-cell and thus humoral immunity is affected. Thus CD40 ligand has a great part in releasing immune responses.

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