Expression of CD2 on BM MCs in mastocytosis.

Multicolor flow cytometry analysis of expression of CD2 on human BM MCs. BM MCs were obtained from a healthy donor (A-C), one with reactive MC hyperplasia (D-F), one with MDS/RA (G-I), and one with SM (J-L). Expression of CD2 and CD25 on KIT^bright MCs was analyzed by multicolor staining. Isotype-matched control mAbs (A,D,G,J), the CD2 mAb S5.2 (B,E,H,K), and the CD25 mAb 2A3 (C,F,I,L) were applied. In the patient with SM, BM MCs were found to react with mAbs against CD2 (K) and CD25 (L). By contrast, BM MCs in RA as well as in the control cases were not recognized by CD2 mAb or CD25 mAb.