PCNA and Huntington disease: PCNA monoclonal antibodies allow cell proliferation to be evaluated in clinical practice using immunohistochemical methods.10-12 In non-neoplastic small lymphocytes in HD tissues, PCNA expression is always low.10-12,26,27 Schmid et al.28 evaluated 23 cases of HD by double labeling with PC-10 monoclonal antibody and CD20 (B cells), and PC-10 and CD45RO (T cells), and found positivity in 50.4% of HRS and 4.3% of lymphocytes.