Common variable immunodeficiency

Common variable immunodeficiency is the most common symptomatic primary immunodeficiency in the world. Primary means the defense system is defective from the start, and what fails here is the production of antibodies, the proteins the body makes to recognize and neutralize an invader.

The defect lies in the B cell, the cell that makes those antibodies: it does not differentiate or function the way it should, and there are often abnormalities as well in the T-cell compartment, whose cells direct the response, and in immune regulation overall. The workers are in the plant, but the antibody line is not producing.

That is why people who have it tend to get repeated infections of the sinuses and lungs, called sinopulmonary infections, plus autoimmune manifestations, in which the defenses attack the person's own body, and granulomatous inflammation, which is the clustering of inflammatory cells in the tissues. All of this happens even though the number of B cells in the blood is normal or nearly normal: they are there, but they do not perform. Treatment rests on immunoglobulin replacement, supplying from outside what is not being made.