Factors associated with IgG levels in adults with IgG subclass deficiency

Abstract

Background Factors associated with IgG levels in adults with IgG subclass deficiency (IgGSD) are incompletely understood. We studied adults with IgGSD with subnormal IgG1 only, subnormal IgG1/IgG3, or subnormal IgG3 only without other subnormal IgG subclasses, IgA, or IgM. We compiled: age; sex; autoimmune condition(s) (AC); atopy; IgG, IgG subclasses, IgA, IgM; IgGsum (IgG1 + IgG2 + IgG3 + IgG4); and D (percentage difference between IgGsum and IgG). We compared attributes of patients with/without subnormal IgG (< 7.00 g/L; subnormal IgG1 subclass groups only) and analyzed IgGsum and IgG relationships. We performed backward stepwise regressions on IgG using independent variables IgG subclasses, age, and sex and on D using independent variables age and sex. Results There were 39 patients with subnormal IgG1 only (89.7% women), 53 with subnormal IgG1/IgG3 (88.7% women), and 115 with subnormal IgG3 only (91.3% women). Fifteen patients (38.5%) and 32 patients (60.4%) in the respective subnormal IgG1 subclass groups had subnormal IgG. Attributes of patients with/without IgG < 7.00 g/L were similar, except that AC prevalence was lower in patients with subnormal IgG1 only and IgG < 7.00 g/L than ≥ 7.00 g/L (p = 0.0484). Mean/median IgG1 and IgG2 were significantly lower in patients with IgG < 7.00 g/L in both subnormal IgG1 subclass groups (p < 0.0001, all comparisons). Regressions on IgG in three subclass groups revealed positive associations with IgG1 and IgG2 (p < 0.0001 each association). Regressions on D revealed no significant association. IgG1 percentages of IgGsum were lower and IgG2 percentages were higher in patients with subnormal IgG1 subclass levels than subnormal IgG3 only (p < 0.0001 all comparisons). Conclusions We conclude that both IgG1 and IgG2 are major determinants of IgG in patients with subnormal IgG1, combined subnormal IgG1/IgG3, or subnormal IgG3 and that in patients with subnormal IgG1 or combined subnormal IgG1/IgG3, median IgG2 levels are significantly lower in those with IgG < 7.00 g/L than those with IgG ≥ 7.00 g/L.

IgG subclass levels in referred hemochromatosis probands with HFE p.C282Y/p.C282Y

“…IgG3 levels were positively associated with IgG1 levels in this study. Subnormal IgG3 levels are often associated with subnormal levels of other IgG subclasses in adults unselected for hemochromatosis diagnoses [ 31 , 45 ].…”

“…IgG4 levels reported as <0.01 g/L were imputed as 0.005 g/L. We excluded total IgG measures from most analyses because IgG levels of adults are determined predominantly by IgG1 and IgG2 levels [ 30 , 31 ]. We compared 15 characteristics of the previous cohort of 51 hemochromatosis probands [ 10 ] with those of the present replication cohort of 157 hemochromatosis probands.…”

Effect of Alkaline Mineral Complex Buffer Supplementation on Rumen Fermentation, Rumen Microbiota and Rumen Epithelial Transcriptome of Newborn Calves

“…IgG, which is secreted by effector B cells in the spleen and lymph nodes, constitutes the main component of immunoglobulins. It plays a crucial role in activating complement, neutralizing multiple toxins and binding antigens during immune responses [28,29]. The observed increase in serum IgG content within the treatment group suggests that the addition of AMCB has a positive effect on immune regulation during anti-infection processes.…”