Immunohistochemical study was performed on skin and lymph node frozen sections from 59 adult T cell leukemia/lymphoma (ATLL) and 10 cutaneous T cell lymphoma (CTCL) patients.
Lymphoma cells of ATLL-infiltrating lymph nodes were of a mature helper/inducer phenotype (OKT4+, OKT8-) in 70.7% of patients, a double helper and suppressor phenotype (OKT4+, OKT8+) in 19.5%, and a defective T cell phenotype /(OKT4-, OKT8-, OKT11+) or (OKT4+, OKT8-, OKT11-)} in 9.8%. In addition, site- or time-dependent phenotypic heterogeniety was found in three of eight patients with repeat biopsies.
There was no apparent relation between histopathological features and reactivities to various monoclonal antibodies except for Ki-1 and FTF-148.
All Ki-1 positive ATLL cases were of large cell type.
FTF-148 was positive mainly in multinucleated giant cells of ATLL.
NK cells (Leu7+), B cells (Leu12+), interdigitating reticulum cells (OKT6+), and histiocytes (LeuM3+) were not significant components in lymph nodes of ATLL.
A number of Langerhans cells (OKT6+ cells) were found in close association with tumor cells in dermal lesions in ATLL as well as in CTCL.
Proliferating cell ratio of ATLL (ratio of Ki-67+ cells) was unexpectedly low (mean: 11.2% in the lymph nodes, 2.9% in the skin). This results suggest that factors other than proliferating potential of tumor cells may play an important role in clinical aggressiveness of ATLL, and the skin may not be a suitable organ for ATLL cell proliferation in despite of cutaneous affinity of ATLL cells.
Monoclonal antibodies, FTF-148 and LeuM3 were useful for distinction between ATLL-involved skin and CTCL.
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