Characterization of the chimeric immune system.

<p>Blood, bone marrow and splenic digests were analysed by flow cytometry to define the leukocyte populations (n = 26 mice). Treatment groups were matched by degree of peripheral blood chimerism prior to IgG injection. hMono = human monocytes. There was no significant difference in degree of chimerism or human granulocyte reconstitution between the experimental groups.</p

Anti-PR3 antibodies cause kidney disease.

<p>(A–C) PAS stained images of glomeruli from chimera mice 6 days after injection with anti-PR3 (n = 18, A, 400×; C, 600×) or control IgG (n = 8, B, 600×). Note extra-capillary proliferation and peri-glomerular inflammation (arrowhead) (A), and mesangiolysis (C, arrow) in anti-PR3 treated mice. (D–F) H & E stained sections of kidney from chimera mice treated with anti-PR3 (D, 40×) or disease control (E, 40×) IgG. There are regions of tubulointerstitial injury, with red cell cast formation (arrow). (F) Demonstrates intense peri-glomerular inflammation in an animal treated with anti-PR3 IgG (arrowhead, 400×). By comparison mice treated with disease control IgG showed minimal glomerular or tubulointerstitial changes. (G) Fractions of glomeruli affected in anti-PR3 (n = 18) and control IgG (n = 8) treated animals (Error bars depict SEM; ***<i>p</i> = 0.001) (H). Degree of tubulointerstitial disease in mice treated with anti-PR3 antibodies and control antibodies (*<i>P</i><0.05, median ± IQ ± max/min values). (Bars = 50 µm).</p

Anti-PR3 antibodies induce infiltration of kidneys with leukocytes of murine and human origin.

<p>Kidney sections were incubated with anti-mCD45 (red) and anti-hCD45 (green) antibodies and images were captured by fluorescence microscopy (T = tubule). Occasional (<5%) glomeruli of anti-PR3 treated mice displayed intense extracapillary leukocyte infiltration (A) in the shape of crescents (arrows). Most glomeruli in animals treated with anti-PR3 antibodies (n = 18) had evidence of intraglomerular (B,G) and peri-glomerular (C,G) leukocyte infiltration. These were comprised mostly of mCD45+ cells, although some hCD45 leukocytes were also present (arrowheads). In addition, there was a significant increase in peri-vascular leukocyte (mCD45+ and hCD45+) infiltration in anti-PR3 treated mice (D,G [per arteriolar section (art.sec.)]). Sections were also stained for deposition of IgG [red] (E,G) and C3 [green] (F,G). IgG was detectable within periglomerular cells, but there was minimal deposition within the glomeruli. Mouse C3 was weakly deposited in glomeruli but was no different between control group (n = 8) and anti-PR3 group (n = 18). Note mouse C3 can be detected normally binding avidly to tubular basement membranes. (Marker = 10 µm) (*<i>P</i><0.05, **<i>P</i><0.01. median ± IQ ± max/min values). (H) Kidney sections from anti-PR3 and control treated animals were incubated with anti-PR3 positive ANCA IgG. In the peritubular capillaries of chimera mice that received anti-PR3 hIgG occasional leukocytes detected by anti-hPR3 hIgG could be detected. No positively stained human neutrophils were seen in glomeruli.</p

Characterization of chimerism in NOD-<i>scid</i>-<i>IL2Rγ^−/−</i> mice.

<p>(A–D) Flow cytometric analysis of leukocytes from tail bleeds six weeks after administration of HSCs (n = 26 mice). (A) Plots showing mouse leukocytes labelled with anti-mouse CD45 antibodies. Compared with control wild-type mouse blood, chimeras have populations of mCD45 negative leukocytes that show SSC characteristics of granulocytes (High), monocytes (Int) and lymphocytes (low). (B) Chimera blood leukocytes express human CD45 and many of these express CD11b. hCD45+,CD11b+ leukocytes predominantly express hCD15 and hCD66b compared with hCD45+,CD11b− leukocytes shown in histograms. (C) A proportion of hCD45+ leukocytes express CD19. (D) Some hCD45 leukocytes are CD14^high and some are CD16+,CD14^low. (E) In chimera bone marrow there are CD11b+ leukocytes which do not express mCD45 and among hCD45+ leukocytes a proportion express CD14 and a proportion express CD66b. (F) In chimera spleen there are CD11b+ leukocytes which express hCD45 and among hCD45+ leukocytes many express both CD14 and CD16. (G) Bone marrow spreads from wild type or chimera mice, labelled with anti-hMPO or anti-hPR3 IgG antibodies (red) purified from patients with vasculitis. Note that chimera bone marrow demonstrates anti-hMPO or anti-hPR3 antibody positive leukocytes with characteristic human neutrophil nuclear morphology. Wild type mouse bone marrow shows no cells positive for these antigens indicating that the anti-human antibodies do not cross react with mouse neutrophils.</p