Common variable immunodeficiency - new insight into the pathogenesis and the quest for a workable classification.

In this editorial we argue that more and more complex classifications for patients with common variable immunodeficiency (CVID) fail to identify those patients at high risk of developing infections. We propose that the minimal requirement to identify such patients is the absolute numbers of total and memory B cells and the IgM response to immunization with polysaccharides. If these data should be confirmed, they will provide the basis for a good classification of a heterogeneous group of patients. This simple, workable classification may result in a clinically useful identification of patients prone to more aggressive infections.