Cerebrospinal fluid and peripheral blood immunophenotyping: flow cytometric dot plots of cerebrospinal fluid (A, C and D) and peripheral blood (B) demonstrating CLL populations. The units on the x- and y-axes are fluorescent intensitity. (A and B) CD5 XCD19 in cerebrospinal fluid and peripheral blood cells, respectively. Four colour cytometry was performed using FACSCalibur (BD Biosciences) flow cytometry. The minority of cerebrospinal fluid cells were positive to double staining showing in circle of the panel A. Panel C shows monoclonality to Ig lambda.