Genotypic analysis of cutaneous T-cell lymphoma: a comparative study of Southern blot analysis with polymerase chain reaction amplification of the T-cell receptor-gamma gene

The diagnosis of early cutaneous T-cell lymphoma (CTCL) is a difficult point in dermatology. Recently, Southern blot analysis (SBA) and polymerase chain reaction (PCR) have been used to detect clonality in initial lesions in which clinical and histological findings are unspecific. Forty-one samples from 25 patients with CTCL were investigated for the presence of T-cell receptor-gamma gene rearrangement using a nested PCR technique and analysed by polyacrylamide gel electrophoresis (PAGE). Conventional SBA was also performed on 28 samples from 20 of these patients. In addition, 20 samples corresponding to patients with large plaque parapsoriasis (LPP), cutaneous B-cell lymphoma (CBCL) and eczema were analysed by PCR in the same way as were the CTCL specimens. Most of the CTCL specimens (81%) showed clonality on PCR analysis. Among patients with mycosis fungoides, 71% of initial patch lesions and 100% of plaques and tumours showed clonal disease. Clonality could be detected in three of four histologically negative post-treatment lesions. Clonal rearrangement was detected in one of three patients with LPP and in three of 10 patients with CBCL. None of the samples corresponding to patients with eczema showed positive results. SBA was significantly less sensitive than PCR in detecting clonality in CTCL patients (42% among early disease and 60% among advanced cases). The results indicate that this PCR/PAGE technique is a reliable and useful method for the detection of clonality in early skin lesions of CTCL patients and probably in the identification of silent extracutaneous involvement.

Mobilization of peripheral stem cells with intensive chemotherapy (ICE regimen) and G-CSF in chronic myeloid leukemia

Seventeen patients with Philadelphia (Ph) chromosome-positive chronic myeloid leukemia (CML) were treated with the ICE regimen plus G-CSF with the aim of mobilizing and collecting Ph-negative peripheral stem cells (PSC) in the setting of an autotransplant program. Fifteen patients had CML in first chronic phase (CP), and two in accelerated phase (AP). Three patients had been previously treated with interferon alpha 2a (IFN). Twelve patients underwent leukaphereses and a mean of 4.7 x 10(8)/kg mononuclear cells were obtained. Four CP patients did not show a significant mobilization peak of CD34+ cells and leukapheresis was not performed; finally, one patient died before apheresis could be performed. Six of the 12 who underwent leukaphereses obtained more than 1.0 x 10(6)/kg CD34+ cells. Eight of the 12 mobilized patients (67%) obtained a major cytogenetic response, including two complete and six partial; in the remaining four patients minimal or absent cytogenetic responses were observed. A higher rate of Ph purging was obtained in patients mobilized early or showing residual Ph-negative cells before mobilization, even if they were in AP. Infectious complications were frequent with a 38% rate of bacteremia recorded and one case of pulmonary aspergillosis resulting in a toxicity similar to that occurring in acute myeloid leukemia-induction chemotherapy. The ICE regimen can promote 'in vivo' purging of the Ph+ cells in 67% of CML mobilized patients (8/12). Failure of mobilization occurs in 65% of patients (11/17), mainly because of poor CD34+ cell yield.

Presentation of a PCR-nuclease protection strategy for minimal residual disease monitoring in B-ALL

Methods for detecting residual malignant cells in patients suffering from lymphoid malignancies have neither been sufficiently sensitive nor easy to routinize, hampering a potential prediction of disease outcome. Taking advantage of clone-specific DNA sequences, generated during lymphocyte differentiation and the polymerase chain reaction, some strategies have been developed for several groups. Up to now the most specific and sensitive methodology, which consists of designing leukemia-specific oligonucleotides, requires sequencing of the complementary determining region III-DNA for each particular patient and is too laborious to be applied to each case for routine monitoring in most hospital laboratories. In an attempt to achieve an easy way to detect residual malignant cells in B lymphoproliferative diseases, we have used a new PCR-based approach, named here as PCR-nuclease protection assay, consisting of: (i) amplification of DNA segments corresponding to the complementarity determining region III of the immunoglobulin heavy chain genes from samples at disease diagnosis; (ii) isolation of the disease-specific single-stranded DNA; (iii) labeling of the single-stranded DNA to generate specific probes; (iv) hybridization to amplified DNA from samples corresponding to different disease phases; and (v) digestion with S1-nuclease. Using this approach, we could detect one malignant cell in a background of 10(5) healthy cells. The sensitivity and specificity of this approach compares with those of the above mentioned specific oligonucleotide strategy in detecting residual malignant B cells. Moreover, this strategy is much less tedious and could be used by most hospital laboratories.