Factors associated with IgG levels in adults with IgG subclass deficiency.

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.

Insulin Resistance and Metabolic Syndrome: Clinical and Laboratory Associations in African Americans Without Diabetes in the Hemochromatosis and Iron Overload Screening Study.

BACKGROUND: We sought to determine associations with insulin resistance (IR) and metabolic syndrome (MetS) in African Americans. METHODS: We studied African American adults without diabetes in a postscreening examination. Participants included Cases: transferrin saturation (TS) >50% and serum ferritin (SF) >300 µg/L (M), and TS >45% and SF >200 µg/L (F), regardless of HFE genotype; and Controls: TS/SF 25th to 75th percentiles and HFE wt/wt (wild type). We excluded participants with fasting <8 h; fasting glucose >126 mg/dL; hepatitis B or C; cirrhosis; pregnancy; or incomplete datasets. We analyzed age; sex; Case/Control; body mass index (BMI); systolic and diastolic blood pressures; neutrophils; lymphocytes; alanine aminotransferase; aspartate aminotransferase; elevated C-reactive protein (CRP >0.5 mg/L); TS; and SF. We computed homeostasis model assessment of insulin resistance (HOMA-IR) using fasting serum glucose and insulin, and defined IR as HOMA-IR fourth quartile (≥2.42). RESULTS: There were 312 Cases and 86 Controls (56.3% men). Ninety-one percent had HFE wt/wt. None had HFE p.C282Y. A significant increasing trend across HOMA-IR quartiles was observed for BMI only. Multivariable regression on HOMA-IR revealed significant positive associations: age; BMI; lymphocytes; SF; and CRP >0.5 mg/L; and significant negative associations: neutrophils and TS. Logistic regression on IR revealed BMI [odds ratio (OR) 1.3 (95% confidence interval 1.2-1.4)] and CRP >0.5 mg/L [OR 2.7 (1.2-6.3)]. Fourteen participants (3.5%) had MetS. Logistic regression on MetS revealed one association: IR [OR 7.4 (2.1-25.2)]. CONCLUSIONS: In African Americans without diabetes, IR was associated with BMI and CRP >0.5 mg/L, after adjustment for other variables. MetS was associated with IR alone.

Implanted ports in adults with primary immunodeficiency.

BACKGROUND: We sought to learn more about the utility and safety of implanted ports for monthly immunoglobulin G infusions in adults with primary immune deficiency. METHODS: We reviewed charts of adults who were referred to a single practice during the interval 2006-2016 for evaluation and management of frequent or severe upper and lower respiratory tract and other infections, subnormal total immunoglobulin G or immunoglobulin G subclasses, and suboptimal responses to polyvalent pneumococcal polysaccharide vaccinations; were diagnosed to have primary immune deficiency; and were advised to undergo immunoglobulin G therapy. RESULTS: Of 606 patients, 20 (19 women, 1 man; 16 immunoglobulin G subclass deficiency, 4 common variable immunodeficiency; 3.3%) needed implanted ports because they had inadequate upper extremity superficial venous access. Median age at diagnosis was 48 years (range: 32-65 years). In total, 17 of the 20 patients preferred monthly in-office intravenous immunoglobulin G treatment to weekly at-home subcutaneous immunoglobulin G. The other three patients could not be treated with subcutaneous immunoglobulin G (unfavorable self-treatment experiences and insurance limitations). Median duration of treatment via implanted ports was 73 months (range: 10-153 months). In the man, the first implanted port was replaced after 26 months due to catheter fracture of unknown cause. His second port has been used for 112 months. We observed no other port-related failure, infections, thrombosis, or other adverse events. CONCLUSION: The utility and safety of implanted ports in adults with primary immune deficiency for whom subcutaneous immunoglobulin G therapy is not desired or feasible are probably similar to those of ports in patients without primary immune deficiency.