Relationship between the switched memory B level and clinical course of coronavirus disease 2019 in patients with common variable immunodeficiency

Introduction:
Among the primary immunodeficiency spectrum, the most common symptomatic type is common variable immunodeficiency (CVID).

Aim:
This study aims to investigate the relationship of class-switched memory B cells (cSMBCs) (CD19⁺CD27⁺IgD⁻) with the clinical course of coronavirus disease-2019 (COVID-19) in patients with CVID.

Material and methods:
This single-centre retrospective study evaluated the clinical features, serum immunoglobulin (Ig) levels, and cSMBC levels of 24 polymerase chain reaction (PCR)-confirmed patients with CVID and COVID-19. The COVID-19 disease severity classification, mortality rate, hospitalisation, symptoms, and PCR positivity durations of the patients were recorded.

Results:
The median age of CVID patients included in the study was 48 (32–58), and 15 of them (62.5%) were female. Disease was severe in 8 (33%) patients, 3 (12.5%) of whom were followed in the intensive care unit and died. The serum IgA, IgM, and CD19⁺ B lymphocyte cell levels were similar between the mild-moderate and severe disease groups. The cSMBC level was significantly lower in the severe disease group (p = 0.01). The hospitalisation, COVID-19 symptom, and PCR positivity durations were significantly longer in the group with a low cSMBC level (p < 0.05). The cSMBC level was negatively correlated with PCR positivity duration (r = 0.397, p = 0.038).

Conclusions:
The cSMBC level is related to the clinical course of COVID-19 in patients with CVID. The cSMBC levels has prognostic value in patients with COVID-19.