Common Variable immunodeficiency(CVID) is the most frequent symptomatic inborn human error in immunity. People with this humoral deficiency have low levels or absence of antibodies, mainly IgG. This makes CVID patients more susceptible to infections and complications such as pneumonia caused by microorganisms whose main defense mechanism is antibody-mediated phagocytosis(AMP). The recognition of these antibodies depends on the Fc receptors. The most widespread are the Fcγ receptors that recognize IgG. Type III Fcγ or CD16 have the lowest affinity, so its activation is highly regulated in order to ensure its activation when the concentration of antigen is high. In CVID is expected a restriction in the phagocytic capacity because of the absence of antibodies, which could be restored with immunoglobulin replacement therapy(IRT). However, very little is known about the status of CD16 and associated functions in phagocytes of this patients. The aim of this work was to establish whether the expression of CD16 in neutrophils and monocytes is related to the phagocytic capacity in patients with CVID receiving or not IRT. For this study, 23 subjects were recruited, 11 patients with CVID, five receiving(IRT) and 6 without treatment, as well as 12 healthy subjects. A peripheral blood was drawn from each person, and the phagocytic capacity of neutrophils and monocytes was evaluated with E. coli-pHRodoGreen. Even that the phagocytes from some of the patients showed a diminished phagocytic capacity, other patients have the same function than control subjects. Likewise, we did not observe differences of phagocytic capacity from total phagocytes or monocyte subsets expressing or not CD16 related to the administration of IRT. Even with the limited number of observations our results suggest that the differential expression of CD16 on monocyte subpopulations is not related to the previously reported decreased phagocytic capacity in CVID patients.
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