Possibilities for the analysis of peripheral blood B cell subpopulations in a routine immunological laboratory.

B cells play a vital role in the defence of the body against infectious agents. Apart from their ability to present antigen to T cells, B cells are mainly producers of antibodies. These play a crucial role in the effective elimination of infection and are also involved in the regulation of the immune response. The analysis of peripheral blood B cell subpopulations that makes it possible to monitor the development of B cells to the stage of antibody producing plasmablasts provides a valuable laboratory parameter which is important for both the study of the pathogenesis and diagnosis of some diseases. Laboratory analysis of B cell subpopulations is now a routinely available laboratory option thanks to the development of multicolour flow cytometry. This article summarizes the core knowledge which is currently applied to the analysis of B cell subpopulations in immunological laboratories.

Chronic immune activation in common variable immunodeficiency (CVID) is associated with elevated serum levels of soluble CD14 and CD25 but not endotoxaemia.

Common variable immunodeficiency (CVID), the most frequent symptomatic immunoglobulin primary immunodeficiency, is associated with chronic T cell activation and reduced frequency of CD4(+) T cells. The underlying cause of immune activation in CVID is unknown. Microbial translocation indicated by elevated serum levels of lipopolysaccharide and soluble CD14 (sCD14) has been linked previously to systemic immune activation in human immunodeficiency virus/acquired immune deficiency syndrome (HIV-1/AIDS), alcoholic cirrhosis and other conditions. To address the mechanisms of chronic immune activation in CVID, we performed a detailed analysis of immune cell populations and serum levels of sCD14, soluble CD25 (sCD25), lipopolysaccharide and markers of liver function in 35 patients with CVID, 53 patients with selective immunoglobulin (Ig)A deficiency (IgAD) and 63 control healthy subjects. In CVID subjects, the concentration of serum sCD14 was increased significantly and correlated with the level of sCD25, C-reactive protein and the extent of T cell activation. Importantly, no increase in serum lipopolysaccharide concentration was observed in patients with CVID or IgAD. Collectively, the data presented suggest that chronic T cell activation in CVID is associated with elevated levels of sCD14 and sCD25, but not with systemic endotoxaemia, and suggest involvement of lipopolysaccharide-independent mechanisms of induction of sCD14 production.