Detection of IgM-ICs bound to the FDC network in PLNs identified in ITP spleens. Sections from 2 ITP spleens were analyzed by immunofluorescence to examine the distribution of (A) DAPI to stain nuclei, CD20 (red), and CD35 (green), and (B) DAPI, IgM (red) and CD35 (green). After staining, the sections were analyzed by confocal microscopy using a Zeiss LSM 710 confocal (×200 magnification; Carl Zeiss). The white ellipse designed using Zen 2010 software represents a proliferating lymphoid nodule identified with IgM staining. (C) Detection of GPIV in ITP spleens: PLN (white arrow) and GC (black arrows); ×200 magnification. (D) The proportion of PLNs identified as containing GPIIb/IIIa was analyzed in 4 ITP spleens versus a control spleen and representative GC and PLN. At least 3 sections of 3 different spleens were analyzed from each specimen; n corresponds to the number of PLN analyzed. (E) DAPI to stain nuclei, CD20 (red), and GPIIb/IIIa (green) on the left or GPIV (green) on the right of the figure. The arrow designated 1 PLN positive from ITP spleen.