We retrospectively analyzed observations in unrelated adults with IgGSD evaluated in a single hematology clinic (1991-2019) and selected those with subnormal serum
IgG2 (<117 mg/dL (<1.2 g/L)) without
corticosteroid therapy to describe: age; prevalence of women; upper/lower respiratory
infection; autoimmune condition(s); atopy; other
allergy; frequent or severe
respiratory tract infection in first-degree relatives;
IgG,
IgG subclasses,
IgA, and
IgM; blood lymphocyte subpopulations;
human leukocyte antigen (
HLA)-A and -B types and haplotypes; and 23-valent pneumococcal
polysaccharide vaccination (
PPSV23) responses. We determined the prevalence of subnormal
IgG2 among unrelated adults with IgGSD without
corticosteroid therapy and compared general characteristics of those with and without subnormal
IgG2.
RESULTS: There were 18 patients (94.4% women) with subnormal
IgG2. Mean age was 52 ± 11 y. Upper/lower respiratory
infection occurred in 94.4%/74.8%, respectively. Autoimmune condition(s), atopy, other
allergy, and frequent or severe respiratory
infection in first-degree relatives occurred in 44.4%, 44.4%, 61.1%, and 22.2%, respectively. Median
IgG2 was 105 mg/dL (83, 116). Subnormal
IgG,
IgG1,
IgG3,
IgG4,
IgA, and
IgM was observed in 66.7%, 50.0%, 100.0%, 5.6%, 33.3%, and 0%, respectively. Lymphocyte subpopulations were normal in most patients. HLA frequencies were similar in patients and controls. Three of 4 patients had no protective S. pneumoniae serotype-specific
IgG levels before or after
PPSV23. These 18 patients represent 7.6% of 236 adults with IgGSD. Prevalence of subnormal
IgG, subnormal
IgG3, and subnormal
IgA was significantly greater in 18 adults with subnormal
IgG2 than 218 adults without subnormal
IgG2. Prevalence of subnormal
IgM was significantly lower in patients with subnormal
IgG2.
CONCLUSIONS: Characteristics of adults with IgGSD with subnormal
IgG2 include female predominance, other immunologic abnormalities, subnormal
IgG3 and/or
IgG1, lack of
HLA-A and -B association, and suboptimal
PPSV23 response.