T cell receptor and immunoglobulin genes in hematologic malignancies

Acute lymphoblastic leukemia with coexpression of CD56 and CD57: case report

The authors present the clinical profile of a 6-year-old girl with an unusual immunophenotype of acute lymphoblastic leukemia (ALL). At the initial presentation, massive hepatosplenomegaly developed. The leukemic cells were myeloperoxidase-negative and morphologically lymphoblastic. These cells were positive for B-precursor-cell (CD10, CD19) antigens and natural killer cells (CD56, CD57). Rearrangements of both immunoglobulin heavy chain alleles and monoallelic rearrangement of T-cell receptors (TCRs)-beta and -delta genes, but not that of TCR-gamma gene, were detected, suggesting that these cells being of B-precursor origin. The patient received chemotherapy for extremely high-risk ALL with a good response. To the authors' knowledge, this is the first pediatric case describing coexpression of CD56 and CD57 on B-lineage ALL.

Molecular analysis in the diagnosis of pediatric lymphomas

Thirty-five pediatric lymphomas were categorized as either Burkitt's lymphoma (BL), lymphoblastic lymphoma (LL), or large cell anaplastic lymphoma (LCAL) by histological and immunophenotypic methods. They were further characterized by molecular analysis of their antigen receptor genes. Southern blot (SB) and polymerase chain reaction (PCR) techniques were compared in the detection of immunogloblin heavy chain gene (IgH) rearrangement. T cell receptor beta (TCR beta) rearrangements were analyzed by SB and TCR gamma gene rearrangements by PCR. The PCR method of IgH and TCR gamma gene analysis was preferred to the SB methods, because there were fewer equivocal results in IgH gene analysis, TCR gamma rearrangement was more frequently detected than TCR beta in both lymphoblastic and large cell anaplastic lymphomas, and the PCR technique was more rapid, required less DNA, and could be used with archival material. In addition, analysis of IgH gene rearrangement by PCR was more specific for assessing B cell lineage. Although most of the molecular data were easily interpreted, occasional ambiguous results were seen due to genetic events other than antigen receptor gene rearrangement affecting the genetic analysis. Thus, it is imperative to interpret these genetic data in the context of adequate morphological and immunophenotypic analysis.

Cytologic findings in a case of T-cell rich B-cell lymphoma: potential diagnostic pitfall in FNA of lymph nodes

Fine-needle aspiration biopsy (FNAB) is a reliable diagnostic technique for most palpable masses. This technique is utilized routinely to diagnose metastatic carcinoma and melanomas in lymph nodes. However, the role of FNAB in the investigation of lymphoproliferative lesions is still controversial. Recent publications have supported the use of FNAB cytology, in conjunction with immunophenotyping, as an accurate, reliable diagnostic modality for the classification of most lymphomas (Sneige et al., Acta Cytol 1990; 34:311-322; Skoog and Tani, Diagn Oncol 1991; 1:12-18; Robins et al., Am J Clin Pathol 1994; 101:569-576; Katz, Clin Lab Med 1991; 11:469-499). We present a case of a T-cell rich, large B-cell lymphoma. Material obtained by FNAB mimicked a reactive process by both cytomorphological and immunophenotypical analysis. This case demonstrates a potential pitfall in the use of FNAB to evaluate lymphoproliferative disorders even when used in conjunction with immunophenotypic studies. The case also emphasizes the need for detailed clinical and prior pathologic information when a cytologic sample is being evaluated for a lymphoproliferative disorder. To our knowledge, the cytomorphologic findings of this particular type of lymphoma have not been previously described as seen on an FNAB.

Lack of T-cell receptor gene rearrangements in cells involved in Langerhans cell histiocytosis

BACKGROUND

Studies using X-chromosome inactivation assays have recently provided evidence in support of a clonal origin of cells affected by Langerhans cell histiocytosis (LCH). A search for more specific clonal markers has led to the investigation for T-cell receptor (TCR) gene rearrangements in cells affected by LCH.

METHODS

Conventional southern blot analysis was used to investigate the possibility of clonal TCR gene rearrangements in tissues affected by LCH wherever possible, otherwise, a polymerase chain reaction (PCR)-based technique was employed for amplification of rearranged joint (J) and variable (V) segments of the TCR-gamma gene including the N-region. 32P-labeled PCR products were then resolved using nondenaturing polyacrylamide gel electrophoresis.

RESULTS

The results using the PCR-based technique showed a lack of clonal rearrangement of the TCR-gamma gene in affected tissues of eight patients with different stages of LCH. Southern blot analyses performed on two of these samples confirmed germline configurations at both the TCR-C-beta and delta-2 gene loci.

CONCLUSIONS

There is no evidence of clonal TCR gene rearrangement in cells involved by LCH. The search for a more specific clonal marker to address whether "'LCH cells" represent a neoplastic clonal transformation of cells with differentiation toward Langerhans cell phenotype continues.

Use of polymerase chain reaction in the detection of clones in lymphoproliferative diseases of the skin

Early-stage mycosis fungoides shows similar clinical symptoms and histological and immunophenotypical features to several benign lymphoproliferative skin disorders. We analyzed T cell receptor gamma gene rearrangement by polymerase chain reaction in the search for monoclonal lymphoid subpopulations in skin infiltrates. Totally, 283 skin biopsies (paraffin-embedded and frozen material) from patients with different malignant and reactive skin diseases were investigated. Using primers for the T cell receptor gamma chain gene, monoclonality was detected in 59 out of 66 (89%) cases of pleomorphic cutaneous lymphoma, in 60 out of 78 (77%) patients with mycosis fungoides, in 11 out of 22 (50%) cases of parapsoriasis en plaques, in five out of 35 (14%) cases of pseudolymphoma, in six out of 15 (40%) patients with lymphomatoid papulosis, and in none out of 64 patients with inflammatory skin diseases. The results show that clonal T cell population can be detected in the majority of patients with cutaneous T cell lymphoma, but the findings have to be correlated with the histological and morphological features.

Primary pulmonary lymphoma. Diagnosis by immunoglobulin gene rearrangement study using a novel polymerase chain reaction technique

A 63-yr-old-woman presented with pulmonary infiltrates and macroglobinemia. Open lung biopsy revealed an interstitial plasma cell infiltrate. Immunocytochemical staining to determine clonality of the infiltrate was negative for both kappa and lambda light chains and therefore was not helpful. Polymerase chain reaction (PCR) amplification of the CDR-III region of the immunoglobulin heavy chain gene revealed that the plasma cells were either monoclonal or biclonal, thus suggesting the diagnosis of a plasmacytoid pulmonary lymphoma. The advantages and limitations of the PCR technique over the traditional method of detecting gene rearrangements, i.e., restriction-digestion of DNA and Southern blotting, are discussed. To our knowledge this patient represents the first reported application of the PCR technique for detecting gene rearrangements to determine the clonality of a lymphoid infiltrate in the lung. This technique can also be applied to determine the clonality of lymphocytes obtained by bronchoalveolar lavage or needle biopsy, or from a pleural effusion.

CD2 + CD19 + acute lymphoblastic leukaemia in 16 children and adults: clinical and biological features. Groupe d'Etude Immunologique des Leucémies (G.E.I.L.)

A small population of CD2 + CD19 + lymphoid cells have been suggested to be common lymphoid progenitors. CD2 + CD19 + biphenotypic ALL account for less than 2% of ALL. We analysed the clinical and laboratory features of a series of 16 patients with CD2 + CD19 + ALL. The incidence of tumoural syndrome was comparable to a previously published series of pre B-ALL but significantly different from that of T-ALL. The mean age of the 11 children of this series was 101 +/- 46 months, and differed significantly from that of children with pre B-ALL (P < 0.01). Complete remission was obtained for all patients except two adults. Only three relapses have been observed. Regardless of the presence of CD2 +, the 16 ALL could be classified as pre B-ALL, according to the nomenclature used by the GEIL. Nine samples could be analysed by Southern blotting. Seven had rearranged IGH genes, usually on both chromosomes. IGK rearrangement was observed in three cases. Only one case had rearranged both TCRG and TCR beta. The patterns observed here and those reported previously follow that of the pre B-ALL which confirms the engagement of most CD2 + CD19 + biphenotypic ALL in the B-lineage.

Molecular biology in the diagnosis and prognosis of solid and lymphoid tumors

The application of molecular biology to the study of human malignancies has led to tremendous gains in our understanding of their pathogenesis. Although their practical applications are still somewhat limited at this point, the use of molecular diagnostic tools is likely to grow at a very rapid rate as newer and more accurate prognostic markers are identified. The availability of reliable prognostic markers should allow earlier intervention in patients with aggressive disease but exhibiting only limited extent of disease at the time of initial diagnosis. Early intervention in such cases could realistically increase the probability of cure, since highly aggressive tumor cells are more likely to be eliminated by early institution of cytotoxic chemotherapy (4). The p53 tumor suppressor gene clearly represents the most promising potential prognostic marker at present, because of both the multiple phenotypic alterations caused by different p53 mutations and the high frequency of p53 mutations which have been observed in a variety of human cancers. Other prognostic markers related to oncogenes and tumor suppressor genes are almost certain to follow. Validation of new prognostic markers requires a knowledge of both histopathologic diagnostic criteria as well as the consequences for the patient of each diagnosis. There is bound to be some "shake-out" in the field of molecular diagnostics just as there was with other recently introduced techniques such as immunohistochemistry and flow cytometry which were found to provide additional useful information for some tumors and not for others. Since the clinical-pathologic studies needed for verification of putative prognostic markers require relatively long periods of follow up, progress in this area will almost certainly lag behind the ability of molecular biologists to identify new and potentially useful prognostic markers. Our collective ability to reap tangible gains in the clinical arena from our heavy investments in molecular biology and biotechnology depends to a large extent on open channels of communication between clinical and basic scientists. As our ever-increasing insights into oncogenic processes spawn new diagnostic and prognostic markers, our priorities should remain focused on those areas which are inadequately addressed by current methods, and we should avoid the technological trap of devising redundant solutions which increase the expense, but not the efficiency of patient care.

Development of a highly specific and sensitive molecular probe for detection of cutaneous lymphoma

Using DNA from formalin-fixed paraffin-embedded tissue of a patient with mycosis fungoides, a highly specific and sensitive molecular probe for the malignant lymphoid cells of this patient was developed. Polymerase chain reaction (PCR) was used to selectively amplify the region of the rearrangement of TCR-gamma genes. Randomly inserted nucleotides between rearranged segments (N-region) were used as a specific marker for the malignant lymphoid clone of this patient. Clonal cells in paraffin-embedded tissue of previous and later biopsies were detected. This technique provides a new and unique tool for retrospective detection of early evolving cutaneous lymphoma, as well as for detection of minimal residual and systemic disease.