Combination of a qualitative (CDR3 spectratyping) and quantitative (flow cytometry) analysis of the TCR repertoire. These graphs give a better visual assessment of the global reduction of the TCR diversity in CTCL. Panel A shows an overall diverse polyclonal CDR3 profile from a representative healthy donor. Panel B demonstrates a similarly diverse profile from a patient with psoriasis. Panel C shows a patient with CTCL with early-stage disease. The loss of complexity is evident even at this stage of disease in the absence of an expanded clone by FACS. Panel D shows a similarly restricted profile from a patient with stage III CTCL without a numerically expanded clone. (E) A highly restricted profile from a patient with CTCL with a malignant clone. (F) With this clone subtracted from the landscape, there is still very little background complexity. The x-axis displays the 24 BV subfamilies, the z-axis shows the CDR3 length distribution (in amino acids), and the z-axis indicates the absolute number of BV⁺ CD4⁺ T cells per cubic millimeter.