B-lymphocyte subpopulations in patients with selective IgA deficiency.
BACKGROUND
Selective deficiency IgA (IgAD) is the most common primary abnormality of immunoglobulin production with unknown pathophysiology. It is genetically related to common variable immunodeficiency (CVID), where besides IgA also IgG and frequently IgM serum levels are decreased. In this study we focused on determination of B-lymphocyte developmental stages and searching for similarities between CVID and IgAD.


METHODS
Using flow cytometry we determined major lymphocyte subpopulations and B-lymphocyte subsets: naïve (CD27(-)IgD(+)), marginal zone cells (CD27(+)IgD(+)), class-switched memory cells (CD27(+)IgD(-)), "double-negative" B cells (CD27(-)IgD(-)), transitional cells (IgM(++)CD38(++)), plasmablasts (CD38(+++)IgM(+) or IgM(-)), and CD21(low)CD38(low) cells in 80 patients with IgAD, 48 patients with CVID, and 80 control persons.


RESULTS
Compared to healthy controls, a decrease in the absolute number and frequency of CD4+ cells (both < 0.001) was observed in IgAD patients. A decrease in the frequency of switched memory cells (P < 0.001), transitional cells (P = 0.035) as well as plasmablasts (P < 0.001) and an increase in the CD21(low)CD38(low) subset (P = 0.007) was observed in IgAD patients compared to control persons. No significant differences were observed in the remaining B-cell developmental subsets. A decrease in CD27(+)IgD(-) (<0.4% of peripheral blood lymphocytes), frequently observed in CVID patients and also previously reported in IgAD, was found in only five patients (6%) with IgAD, two of them being first-degree relatives of CVID patients.


CONCLUSIONS
Our results show a decrease of terminally differentiated B-lymphocyte subsets in patients with IgAD, similar as previously found in patients with CVID, but these results are less expressed than in CVID patients.
Department of Clinical Immunology and Allergology, St. Anne's University Hospital, Faculty of Medicine, Masaryk University, Pekarska 53, 656 91, Brno, Czech Republic.
Jana
J
Nechvatalova
Zdenka
Z
Pikulova
Dagmar
D
Stikarovska
Sava
S
Pesak
Marcela
M
Vlkova
Jiri
J
Litzman
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016175:B-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology*; D002454:Cell Differentiation; D017074:Common Variable Immunodeficiency / Q000276:immunology*; D005260:Female; D006801:Humans; D017098:IgA Deficiency / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D055815:Young Adult