CD1A and Langerhans cell histiocytosis: We performed immunostaining with antibodies against Ki-67, the LC antigen CD1a, CD68 (which is also expressed by macrophages), the T cell antigen CD3, and the B cell antigen CD20 in tissue samples from a retrospective series of 16 patients with various clinical forms of LCH (patients 1–12, 31, and 35–37; Table 1).