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Polymorphs may play a part in sickle cell retinopathy

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New evidence indicates that leucocytes and leucocyte adhesion molecules feature in blocking retinal capillaries in sickle cell retinopathy. Retinas from patients with sickle cell disease showed significantly higher immunoreactivity of intercellular adhesion molecule 1 (ICAM-1), vascular adhesion molecule 1 (VCAM-1), and P-selectin than retinas from a control. ICAM-1 and P-selectin reactivities were highest in sections of retina whereas VCAM-1 reactivity was most significantly increased in “sea fans”, especially compared with sections of retina from the control. Sea fans are histological features that result from neovascularisation in the pre-retinal area close to non-perfused peripheral retina.


Various sea fans in retinal sections labelled with anti-perlecan antibody, specific for viable blood vessels. (A) Sea fan composed of mostly large caliper dilated vessels; (B) sea fan of small diameter capillary like vessels; (C) sea fan with viable and infarcted (arrowheads) vessels. Haematoxylin counterstain. (A), (B) 120x, (C) 80x.

Polymorphonuclear leucocytes (PMNs) were significantly more numerous in the retinas of the patients—about three times more than in the control—and in sea fans compared with retina in the patients.

The distribution of adhesion molecules was assessed by visually scoring histochemically stained thin sections of retinas in eyes obtained at necropsy and by densitometry. PMNs were counted in sections and counts expressed per mm2 of retina. Three different areas of the retina were sectioned in each case. Nine samples were obtained from five patients with sickle cell disease; one was a vitrectomy sample. One subject without sickle cell disease, who had been a control in a previous study of diabetic retinopathy, provided the control samples.

Research in sickle cell disease has hinted at involvement of PMNs in adhesion to capillary endothelium in the retina, which is a precursor to retinopathy. Patients had higher amounts of cytokines, white cells, and soluble ICAM-1 and VCAM-1 in their blood.