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The expression of CD14, CD18, and major histocompatibility complex II on unprimed monocytes from healthy donors after incubation with IgG from patients with antineutrophil cytoplasmic autoantibody (ANCA)-positive active Wegener's granulomatosis (n = 6) and microscopic polyangiitis (n = 6) in comparison with IgG from healthy controls (n = 6) was studied. Monocytes were incubated with IgG (100 microg/ml) at 37 degrees C, and expression of antigens was measured by fluorescence-activated cell sorter after 18 h. Cytoplasmic ANCA (C-ANCA) IgG and perinuclear ANCA (P-ANCA) IgG in comparison with control IgG increased the expression of CD14 (49.2% [SD: 37, P:0. 001], and 55.8% [SD: 41, P:0.05]) and CD18 (11.4% [SD: 18, P:0. 01] and 8% [SD: 26, P:0.05]) but did not change the major histocompatibility complex II expression. Upregulation of CD14 started after 6 h and reached a peak after 10 to 14 h of incubation and was not inhibited by polymyxin B. F(ab)(2) fragments of C- and P-ANCA IgG also increased expression of CD14 and CD18 as compared with control IgG F(ab)(2), but for CD14 less than with complete IgG. ANCA IgG depleted of antiproteinase 3 and antimyeloperoxidase antibodies by immunoadsorption failed to upregulate CD14. Monoclonal murine antibodies against proteinase 3 and myeloperoxidase yielded a strong upregulation of CD14 when compared with an isotype control or human control IgG. The data show that CD14 and CD18 are upregulated on monocytes by C- and P-ANCA IgG in vitro, as well as by monoclonal antibodies against proteinase 3 and myeloperoxidase and that this effect is not dependent on Fc gamma receptor crosslinking. Upregulation of CD14 and CD18 on monocytes by ANCA suggests a pathogenetic role of ANCA monocyte interactions in systemic vasculitis.

The increase in GFR after an amino acid (AA) load, the so-called renal functional reserve, is impaired in the aged rat. Whether the renal functional reserve predicts the progression of renal disease in humans is controversial, but it is possible that age-related alterations of renal hemodynamics are relevant for the evolution of renal disease in the elderly. We compared renal hemodynamics before and after an AA infusion in 15 healthy normotensive subjects of young age (seven women, eight men; median age, 26 yr; range, 23 to 32) and in 10 subjects of old age (six women, four men; median age, 70 yr; range, 61 to 82) on normal dietary protein intake. Baseline GFR and effective RPF were measured after 12 h of fasting by the inulin (Cin) and para-aminohippurate (Cpah) steady-state infusion techniques. The renal functional reserve was examined after an overnight AA infusion (7% solution; 83 mL/h). Median basal Cin and Cpah were significantly lower (P < 0.01) in the elderly (102 and 339 mL/min per 1.73 m2) than in the young subjects (122 and 647 mL/min per 1.73 m2), but virtually all GFR values of the elderly were still within the normal range. Median Cin upon infusion of AA was 118 mL/min per 1.73 m2 (range, 98 to 137) in the elderly and 146 (range, 120 to 171) in the young, respectively. Corresponding values of Cpah were 349 mL/min per 1.73 m2 in the elderly versus 689 mL/min per 1.73 m2 in the young. Cin increased significantly (P < 0.01) after the AA load in both young and elderly subjects.(ABSTRACT TRUNCATED AT 250 WORDS)