American Society of Hematology

Figure 5.

$Protein G purified IgG from human ITP serum retained the capacity to trigger macrophage phagocytosis of platelets. Serum from patients with ITP or NHS were fractionated via protein G into purified IgG and IgG-depleted protein fractions. Unfractionated whole serum, IgG-purified, or IgG-depleted fractions were then incubated with normal donor platelets and assessed for the ability to trigger macrophage phagocytosis. Each serum or serum fraction was evaluated over n = 3 to 5 independent experiments and whole NHS was evaluated over n = 7 independent experiments. THP-1-CD16A macrophages were used as phagocytes. Phagocytosis was performed as described in the “Methods” and quantified from fluorescent photomicrographs. ∗∗P ≤ .01, by ordinary one-way analysis of variance (ANOVA) with Šídák’s multiple comparisons test, except for the comparisons of ITP 17 sera vs ITP 17 IgG-purified and ITP 4 sera vs ITP 4 IgG-depleted, which were computed via the nonparametric Kruskal-Wallis test with Dunn’s multiple comparisons test. Data was tested for normal (Gaussian) distributions by the Shapiro-Wilk test. Phagocytic index: number of phagocytosed platelets per 100 counted macrophages. Error is presented as mean ± 1 SD.$

Protein G purified IgG from human ITP serum retained the capacity to trigger macrophage phagocytosis of platelets. Serum from patients with ITP or NHS were fractionated via protein G into purified IgG and IgG-depleted protein fractions. Unfractionated whole serum, IgG-purified, or IgG-depleted fractions were then incubated with normal donor platelets and assessed for the ability to trigger macrophage phagocytosis. Each serum or serum fraction was evaluated over n = 3 to 5 independent experiments and whole NHS was evaluated over n = 7 independent experiments. THP-1-CD16A macrophages were used as phagocytes. Phagocytosis was performed as described in the “Methods” and quantified from fluorescent photomicrographs. ∗∗P ≤ .01, by ordinary one-way analysis of variance (ANOVA) with Šídák’s multiple comparisons test, except for the comparisons of ITP 17 sera vs ITP 17 IgG-purified and ITP 4 sera vs ITP 4 IgG-depleted, which were computed via the nonparametric Kruskal-Wallis test with Dunn’s multiple comparisons test. Data was tested for normal (Gaussian) distributions by the Shapiro-Wilk test. Phagocytic index: number of phagocytosed platelets per 100 counted macrophages. Error is presented as mean ± 1 SD.

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