We designed a study to investigate the morphological expression of imm
une responses in the palatine tonsils from patients with IgA nephropat
hy. To distinguish between the histological characteristics of the ton
sils in habitual tonsillitis (47 patients) and IgA nephropathy (11 pat
ients), we studied the T nodules, B-lymphoid follicles, germinal cente
rs, areas of mixed T and B lymphocytes, lacunar epithelium and connect
ive tissues; then we compared patients with habitual tonsillitis and I
gA nephropathy. The T nodules in patients with IgA nephropathy were en
larged, and this change was not accompanied by atrophy of B-lymphoid f
ollicles. Morphologically, primary T nodules were predominant. In reac
tive lymph nodes, T nodules generally play an important role in the ex
tra-follicular maturation of stimulated B lymphocytes into Ig-secretin
g plasma cells. Therefore the enlarged primary T nodules remind us tha
t this maturation may occur more frequently in the tonsils of patients
with IgA nephropathy than in those with habitual tonsillitis. This su
ggests that some immunoregulatory dysfunction exists in the secretory
immune system of mucosa-associated lymphoid tissues in patients with I
gA nephropathy.