SUMMARY+ T cells>CD57 + T cellsiCD8 + T cellsiNK cells. However, the CD3-stimulated proliferation of both NK-type T cells was smaller than that of CD8 + T cells partly because NK-type T cells were susceptible to apoptosis. In addition to NK cells, NK-type T cells but not CD8+ T cells stimulated with cytokines, expressed cytoplasmic perforin and granzyme B. Furthermore, CD3-stimulated IFN-c production from peripheral blood mononuclear cells (PBMC) correlated with the proportions of CD57 + T cells in PBMC from donors. Our ®ndings suggest that NK-type T cells play an important role in the T helper 1 responses and the immunological changes associated with ageing.

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SUMMARYMatrix metalloproteinases (MMPs) play an important role in the progression of tumour cells and the invasion of inflammatory cells by degrading the extracellular matrix. In the MMP family, MMP-9 gelatinase is thought to contribute to the pathogenesis of inflammatory arteritis by disrupting the elastic lamina. The aim of the present study is to investigate the potential role of MMP-9 in Kawasaki disease (KD), an acute type of systemic vasculitis in children. We studied the total levels of MMP-9 (free proMMP-9 and free MMP-9) in the sera using a new assay system and the expression of MMP-9 mRNA in the leucocytes using reverse transcription-polymerase chain reaction in 18 patients with KD, 10 patients with sepsis and 10 healthy children (HC). The serum MMP-9 levels were significantly higher (P , 0´01) in the acute phase of KD than in the acute phase of sepsis and HC. In the time course of KD, the serum MMP-9 levels decreased significantly (P , 0´01) from the subacute through the convalescent phases. In the acute phase of KD, the serum MMP-9 levels showed a significantly positive correlation (P , 0´05) with the circulating leucocyte counts, especially the neutrophil counts. Furthermore, the expression of MMP-9 mRNA in the circulating leucocytes increased in the acute phase of KD and decreased from the subacute through the convalescent phases. These findings indicate that an excessive amount of MMP-9 is present in the plasma during the acute phase of KD, thus suggesting that circulating leucocytes may be a source of the MMP-9 secreted into the circulation.