Apoptosis of peripheral blood mononuclear cells in Kawasaki disease

Kawasaki disease (KD) is an acute systemic vasculitis characterized by marked depletion of peripheral lymphocytes in the acute stage of the disease. We evaluated the degree of apoptosis of peripheral blood mononuclear cells (PBMC) in KD and investigated whether the Fas-Fas ligand system is involved in inducing apoptosis in KD.

Fifteen patients with KD were classified into 2 groups, Group KW1 (initial stage of disease, or fever < 5 days) and Group KW2 (fulminant stage of disease, or fever > 5 days). PBMC were isolated and after 5, 24, and 48 h incubation stained and analyzed by flow cytometry. The levels of serum soluble Fas were measured by ELISA. mRNA expression of Fas ligand was evaluated by reverse transcription polymerase chain reaction.

The degree of apoptosis at 24 h was 20.2 +/- 5.6% in Group KW1, higher than that of normal (p < 0.05) and febrile controls (p < 0.01); and 10.8 +/- 2.8% in Group KW2, lower than that of normal (p < 0.01) and febrile controls (p < 0.01). At 48 h the degree of apoptosis was 37.7 +/- 4.2% in Group KW1, significantly higher than normal (p < 0.01) and febrile controls (p < 0.01); and 17.1 +/- 5.6% in Group KW2, lower than normal (p < 0.01) and febrile controls (p < 0.01). The mean level of serum soluble Fas in the acute stage of KD was 0.45 +/- 0.26 ng/ml, significantly lower versus the subacute stage (1.06 +/- 0.40 ng/ml) (p < 0.01). FasL of mRNA was expressed in PBMC of all patients with acute stage KD. whereas no expression was noted in the subacute stage of disease.

Marked decrease of peripheral blood lymphocytes in acute stage KD may be caused by the upregulated apoptosis of lymphocytes; Fas-Fas ligand may be involved in this upregulation.