We measured the serum total
IgG levels in 159 Japanese
narcolepsy-
cataplexy patients positive for the
HLA-DQB1*0602 allele, 28
idiopathic hypersomnia patients with long sleep time, and 123 healthy controls (the
HLA-DQB1*0602 allele present in 45 subjects). The serum levels of each
IgG subclass were subsequently measured. The distribution of serum
IgG was significantly different among healthy controls negative for the
HLA-DQB1*0602 allele (11.66+/-3.55 mg/ml), healthy controls positive for the
HLA-DQB1*0602 allele (11.45+/-3.43),
narcolepsy patients (9.67+/-3.38), and
idiopathic hypersomnia patients (13.81+/-3.80). None of the following clinical variables, age, disease duration, Epworth
Sleepiness Scale, smoking habit and BMI at the time of blood sampling, were associated with
IgG levels in
narcolepsy or
idiopathic hypersomnia. Furthermore we found the decrease in
IgG1 and
IgG2 levels, stable expression of
IgG3, and the increase in the proportion of
IgG4 in
narcolepsy patients with abnormally low
IgG levels. The increase in the proportion of
IgG4 levels was also found in
narcolepsy patients with normal serum total
IgG levels.
Idiopathic hypersomnia patients showed a different pattern of
IgG subclass distribution with high
IgG3 and
IgG4 level, low
IgG2 level, and
IgG1/
IgG2 imbalance.
CONCLUSIONS/SIGNIFICANCE: