Use of Monoclonal Antibodies for the Diagnosis of T-cell Malignancies: Applications and Limitations

Analyses of T-cell receptor beta-chain genes by Southern blotting in known and suspected cutaneous T-cell lymphoma. A study of 67 samples from 32 patients

In this study we have investigated the configuration of the T-cell receptor (TCR) beta-chain genes in benign cutaneous conditions (n = 5) and known (n = 22) or suspected (n = 5) cutaneous T-cell lymphoma (CTCL). Sequential biopsies from skin, lymph node, blood and/or bone marrow were available in 12 cases of the 22 confirmed CTCL, and a total of 67 samples were analysed. In the benign conditions, clonal rearrangements of the TCR beta-chain genes were seen in neither skin nor blood samples. In contrast, in CTCL clonal rearrangements were detected in all skin samples from plaque or tumour lesions of mycosis fungoides. Clonal TCR rearrangements were also present in skin and blood samples from two patients with Sèzary's syndrome, and in skin and blood samples from three of five patients with clinically suspected CTCL. In 10 patients with large cell lymphomas, clonal rearrangements were detected in skin samples in half of the cases. In the remaining patients, clonal TCR rearrangements could not be detected in the skin, but only in the blood and/or bone marrow specimens. Results from the analyses of sequential biopsies showed identical patterns of rearrangement in 11 patients. In the remaining patient, the pattern of rearrangement differed between skin and lymph node. These data confirm and extend previous reports and indicate that analysis of TCR beta-chain genes by Southern blotting forms a useful supplement to other methods for the diagnosis of known and suspected CTCL. They also emphasize the importance of studying not only skin, but also extracutaneous sites.

Use of antibodies against the variable regions of the T-cell receptor alpha/beta heterodimer for the study of cutaneous T-cell lymphomas

Recent studies have suggested that antibodies against the variable (V) regions of the T-cell antigen receptor (TCR) may be used as markers for clonality and malignancy in T-cell infiltrates. We have investigated this by examining biopsy samples from 45 patients with cutaneous T-cell lymphomas (CTCL) for reactivity with seven antibodies against different V-gene families on the TCR alpha/beta heterodimer, i.e. ICI (V beta 5a), W112 (V beta 5b), OT145 (V beta 6a), 16G8 (V beta 8a), S511 (V beta 12a), F1 (V alpha 2a) and LC4 (alpha beta Va). Serial biopsies were available in 13 patients and a total of 62 samples were studied. The neoplastic cells in five cases were positive for either V beta 5 (one case), V beta 6 (one case), V beta 8 (two cases) or V beta 12 (one case). In the remaining 40 cases, no staining was seen of the neoplastic cells. These findings indicate that while antibodies against the TCR V-regions may be used as clonotypic markers for certain T-cell neoplasms, there is as yet not a sufficient number of anti-TCR V-region antibodies available for the routine diagnosis of these conditions.

Leukaemia as a manifestation of large cell lymphoma

A leukaemic phase is uncommon in large cell lymphoma, particularly at presentation of the disease, and very few cases have been reported since immunological markers became available. We have studied 24 cases presenting over a period of 15 years. 16 were B-lineage and eight T-lineage. In five patients the large cell lymphoma represented a transformation of a preceding low grade, small cell lymphoproliferative disease. Three other patients with T-lineage large cell lymphoma presented with skin infiltration (two cases) or lymphoma-associated nephrotic syndrome (one case) 3-9 months before leukaemia occurred. The other 16 patients (12 B-lineage and four T-lineage) presented with de novo large cell leukaemia/lymphoma. With the exception of skin infiltration, clinical features did not differ between T and B-lineage cases. Prognosis was generally poor although a minority of patients lived 1-2 years. Median survival was 7 months. In the B-cell lymphomas immunological markers were those expected but among the T-cell cases there were many unusual immunophenotypes with frequent failure to express markers which are usually positive in peripheral T cells. Without the availability of immunological markers diagnosis would have been difficult, with acute myeloid leukaemia being the most important differential diagnosis. T-lineage and B-lineage cases could not be distinguished on cytological features. In the majority of cases the cells were very pleomorphic with nuclear lobulation, prominent nucleoli and marked cytoplasmic basophilia being commonly observed. Marked nuclear lobulation was not confined to T-lineage cases but was seen also in seven of 12 cases of de novo B-lineage leukaemia/lymphoma; it was readily apparent in histological sections and on ultrastructural examination.