See:
Holly (Ilex spp.) - Boron Deficiency
Cause Several factors can lead to red spots on holly leaves including boron deficiency, ovipositing damage of certain insects, fungus-induced corky red spots (scab), spine injury, which results in holes or corky scratches, and copper-based pesticides. The amount of red color associated with spine injury (holes) depends on the variety.
Symptoms Copper spot-small, discrete purple spots with light centers on the leaves' undersides. On blue-stem cultivars such as French-English, spots on the leaf underside often produce purple blotches on the upper surface. A corresponding purple blotching may not occur on the upper leaf surface of green-stem cultivars. One grower reported that in a mixed planting sprayed with tribasic copper sulfate in early October, 'French-English' showed severe leaf spotting, 'Variegated' showed light spotting, and 'Rederly' was free of leaf spotting.
Control Identify the primary cause and then take corrective measures.
Reference Herridge, E., and Lambe, R. 1960. A holly leaf spot associated with the use of copper fungicides. Phytopathology 50:84.