Antiplatelet antibodies in Ig extracts of breast milk. (A-C) Flow cytometry histograms of antiplatelet antibodies in milk-Ig of A.H. (a representative ITP patient [black line]) and controls (gray line) detected by anti-human antibodies: IgA/IgM/IgG-phycoerythrin, anti-IgA-fluorescein isothiocyanate, and anti-IgG-fluorescein isothiocyanate. (D) Detection of anti-α_IIbβ₃ antibodies in milk-Ig from A.H. The milk-Ig was incubated with baby hamster kidney cells expressing α_IIbβ₃ (black line) or mock cells (gray line). Antibodies were detected by anti-human IgA/IgM/IgG-phycoerythrin detected in FL2 by flow cytometry. FL1, fluorescence of fluorescein isothiocyanate; FL2, fluorescence of phycoerythrin. (E) Statistical analysis of the 3 different groups of women: ITP patients, R-ITP patients (women who had recovered from ITP and during pregnancy had normal platelet count), and controls. Each column represents mean + standard error of the mean of the frequency of positive results. Frequency was calculated for each sample as the number of positive results among the total number of experiments performed. Analyses were performed by comparing frequencies of detected antibody in ITP and R-ITP women with the controls by using GraphPad software and 2-way analysis of variance with Tukey’s multiple comparisons test. *P < .05; **P < .01.