Prolymphocytic leukaemia of T-cell type: immunological, enzymatic and ultrastructural morphometric characteristics

Single-cell screening of multiple biophysical properties in leukemia diagnosis from peripheral blood by pure light scattering

Histology and histopathology are based on the morphometric observations of quiescent cells. Their diagnostic potential could largely benefit from a simultaneous screening of intrinsic biophysical properties at single-cell level. For such a purpose, we analyzed light scattering signatures of individual mononuclear blood cells in microfluidic flow. In particular, we extracted a set of biophysical properties including morphometric (dimension, shape and nucleus-to-cytosol ratio) and optical (optical density) ones to clearly discriminate different cell types and stages. By considering distinctive ranges of biophysical properties along with the obtained relative cell frequencies, we can identify unique cell classes corresponding to specific clinical conditions (p < 0.01). Based on such a straightforward approach, we are able to discriminate T-, B-lymphocytes, monocytes and beyond that first results on different stages of lymphoid and myeloid leukemia cells are presented. This work shows that the simultaneous screening of only three biophysical properties enables a clear distinction between pathological and physiological mononuclear blood stream cells. We believe our approach could represent a useful tool for a label-free analysis of biophysical single-cell signatures.

Ultrastructural morphometry of human leucocytes in health and disease

In this review, the literature on ultrastructural morphometry of each of the main types of human blood leucocytes has been considered, together with the technical and numerical procedures essential for valid analysis. Quantitative data have been reported for these cell types in health and comparisons have been made with those in disease states. In monocytes, and in macrophages developing from them, subtle ultrastructural differences have been detected and quantitated in malignant lymphoma; as the mononuclear phagocytes were not themselves neoplastic, the changes may have related to defects in host defence. Change in the ultrastructural characteristics of leukaemic monoblasts have also been reported. Lymphocytes and malignant lymphoid cells have been extensively investigated: differences between different types and subsets have been shown to be present in both normal lymphocytes and their malignant counterparts in leukemias and lymphomas. Particular attention has been paid to morphometric assessment of nuclear shape and size in these disorders and to its possible value as a diagnostic tool. Granulocytes have so far been the subject of few morphometric studies, although in hypereosinophilic syndrome, cellular changes have been defined and have thrown light on the abnormal pattern of degranulation. There have also been scattered reports on the cells of acute myelogenous leukaemia. The use of computers and sophisticated statistical packages has greatly facilitated the application of multiple comparison procedures and has permitted discriminant analysis to be carried out where appropriate. This review shows that ultrastructural morphometry of leucocytes will have an increasing application in clinical pathology.

T-cell prolymphocytic leukemia with an unusual phenotype CD4+ CD8+

A patient with T-cell prolymphocytic leukemia (T-PLL) is described. The outcome was poor, with death 8 months after diagnosis, despite several therapeutic interventions. The cells carried both CD4 and CD8 epitopes, but other thymocytic markers were absent. The spleen showed infiltration of CD4+ CD8+ prolymphocytes in the red pulp and in T-cell-dependent areas of the white pulp. Immunologic function studies revealed proliferation after stimulation with mitogens and even several antigens. However, in the mixed lymphocyte culture the T-PLL cells did not proliferate. Cytotoxic T-cells could not be induced. In T-non-T recombination experiments neither helper nor suppressor cell function was found for pokeweed mitogen-dependent plasmablast generation of normal B-cells. Cytogenetically, many abnormalities were found. Among them, 14q+; absence of chromosomes 8, 11, and 22; and the presence of large marker chromosomes and fragments.

The morphological spectrum of T-prolymphocytic leukaemia

The morphology of the cells from 29 cases of T-prolymphocytic leukaemia (T-PLL) was studied by light (LM) and transmission electron microscopy (TEM) and was compared with that of 33 B-cell PLL. The membrane phenotype of T-PLL cells was T4+, T8- in two-thirds of the cases, others being T4- T8+ or T4+ T8+. Two morphological types of T-PLL were defined according to the nuclear features: regular (55% of cases) and irregular (45% of cases). T-PLL cells with a regular, round or oval, nuclear outline resembled B-PLL cells but had less abundant cytoplasm and a higher nucleo-cytoplasmic ratio. Irregular T-prolymphocytes displayed a distinct convoluted nucleus. A 'small-cell' variant of T-PLL was recognized by TEM in six cases in which the diagnosis was uncertain by LM. A characteristic of all types of T-prolymphocytes by LM was the presence of a deep basophilic cytoplasm which by TEM corresponded to clusters of ribosomes and endoplasmic reticulum. No differences in clinico-haematological features or membrane markers were apparent between the morphological types of T-PLL, although it was noted that the three T4- T8+ cases had irregular cells and four of the small cell variant were T3- T4+. TEM permits a more precise assessment of the cytoplasmic organelles and nucleolus than LM analysis and facilitates the distinction between T-PLL and other leukaemias with a mature T-cell phenotype, namely adult T-cell leukaemia/lymphoma. Sezary syndrome and T-chronic lymphocytic leukaemia.

The human T-cell leukemias: clinical, cytomorphologic, immunophenotypic, and genotypic characteristics

The distribution of the conventional lymphoid cell markers on T lymphocytes and the principal panels of monoclonal antibodies used to recognize distinctive T-lymphocyte-associated differentiation antigens are discussed. These reagents have been used to probe the early and late stages of T-cell differentiation, and a hypothetical schema of T-cell differentiation has been constructed. Application of these reagents to the investigation of neoplastic T cells has resulted in the determination of the subset of origin and the stage of differentiation of the neoplastic cells in T-cell-derived lymphoproliferative malignancies. Recent advances in molecular biology have made possible the Southern blot hybridization analysis of DNA extracted from neoplastic T cells for patterns of T-cell-receptor gene rearrangements. Examination of these patterns in benign and malignant T and non-T cell has provided the basis for the use of T-cell-receptor gene rearrangements as specific genetic markers of T-cell lineage, clonality, and differentiation. These and other advances have resulted in the delineation of a new category of T-cell neoplasia, the adult T-cell leukemia/lymphoma syndrome. They have also demonstrated that the majority of clinically indolent neoplasms composed of large granular lymphocytes in so-called T gamma-lymphoproliferative disease are monoclonal proliferations. Further phenotypic, functional, and genotypic analyses of the T-cell malignancies should provide better understanding of T-lymphocyte differentiation and heterogeneity. Such studies should also lead to better clinicopathologic correlations and greater understanding of the basis for the clinical diversity of the T-cell-derived lymphoproliferative malignancies.

T cells in patients with chronic T gamma lymphocytosis: morphology, cytochemistry, ultrastructure and immunological characteristics

We have studied the morphology and cytochemistry in relation to the immunological phenotyping and functional properties of T cells from eight patients with chronic T gamma lymphocytosis. At the light microscopic level the morphology of the patients' lymphocytes was similar to that described for large granular lymphocytes. Ultrastructurally, a division into two groups could be made on differences in the amount of cytoplasm and the location and the more irregular form of the nuclei. The lymphocytes of one group (five patients) had in common the phenotype Fc gamma +, T3 +, T4 -, T8 +, Ia -, M1 - and demonstrated (with the exception of one patient) the same functions: presence of K-cell activity, absence of NK, helper and suppressor cell activities. In the other group (three patients), the lymphocytes of one patient showed the same phenotype and functions as those indicated above. The other two patients both lacked the T8 antigen on their lymphocytes but were different with regard to other surface markers. In addition, their cells were functionally identical: both demonstrated NK- and K-cell activity. Thus in this group of eight patients with chronic T gamma lymphocytosis, the immunological and functional subdivision paralleled in part a morphological division at the ultrastructural level.

Six new cases of prolymphocytic leukemia with heterogeneous prognosis. Clinical and immunologic features, light microscopy, and ultrastructural findings

The clinical features and diagnostic evaluation of six patients affected by prolymphocytic leukemia (PLL), are described. Some of the cases deviate from a relatively uniform and aggressive clinical course of the disease entity. An actuarial survival analysis of 60 cases gathered from the literature and the authors' experience indicate that the cases showing the most prolongated evolution may reach 30% of the total. The different aggressiveness in the clinical course of these patients does not depend on the efficiency of the therapies applied. The percentage of prolymphocytes (PL) in peripheral blood throughout the clinical course was variable and not depending on the treatments used. This fact, in conjunction with (1) the presence of cellular types deviated from the typical PL and detected both at optical and ultrastructural levels and (2) the existence of cases of PL with minimal splenomegaly and leukocyte counts of less than 50 X 10(9)/liter, could lead to an underdiagnosis of PLL and hinder the actual cognition of the natural medical history of the disease.

Functional and phenotypic analysis of a T cell prolymphocytic leukemia

Peripheral blood mononuclear cells obtained from a patient with prolymphocytic leukemia expressed the surface membrane markers characteristic of resting mature T helper lymphocytes. These cells responded to the T cell mitogens PHA and Con A in a blast transformation assay but not the anti-T cell monoclonal antibody Leu 4 and the B cell mitogen, PWM. The concentration of PHA or Con A eliciting maximum blast transformation was less than that required by normal mononuclear cells. The leukemic cells recognised and responded to allogeneic pooled mononuclear cells in a mixed lymphocyte culture. In addition, although they did not express Ia antigens, they served as effective stimulators in the mixed lymphocyte reaction. Consistent with the helper phenotype, the leukemic cells did not produce suppressor factors, but provided help for normal B-enriched lymphocytes to respond to PWM as assessed by both blast transformation and IgG production. T lymphocyte colonies developed when the leukemic cells were treated with PHA during a 20 h liquid culture prior to being seeded into semisolid agar medium containing either PHA or an IL2-containing lymphokine. There was no growth when untreated cells were seeded directly into IL2-containing agar. Analysis of colony formation indicated that, as with normal resting T lymphocytes, proliferation occurred in two distinct steps; activation in response to PHA and replication in response to IL2-like growth factors. These findings demonstrate that in this case the helper T prolymphocytes have the functional capabilities of normal mature T lymphocytes as predicted from their helper phenotype.

Functional and multimarker analysis of T-cell chronic lymphocytic leukaemia

The morphology, immunophenotype, cytoenzymatic and functional activities of T lymphocytes from 4 patients with chronic lymphoproliferative disease of T-cell origin were studied. Clonal proliferation was demonstrated by distinctive chromosomal abnormalities involving chromosomes 2 and 14. Patients 1 and 2 were classifiable as OKT4+ T-cell chronic lymphocytic leukaemia (T-CLL) and patient 3 as OKT4+/OKT8+ T-CLL, with helper function in vitro only in patient 1. Patient 4 has low-grade lymphocytosis with benign clinical course, with cells showing morphology of large granular lymphocytes (LGL), and immunophenotype HNK-1+, ER+, Fc gamma receptor+, OKT3+, OKT11+ and OKT8+, as well as natural killer activity, radiosensitive suppressor activity on Ig secretion and responsiveness to PHA; this case was interpreted as LGL leukaemia. This study indicates that a large proportion of cases of true T-CLL may belong to the OKT4 subset, and that extensive investigations should be made of the lymphocytic OKT8+/T gamma forms to characterize them precisely.

T-cell prolymphocytic leukemia with helper-cell phenotype and a review of the literature

The majority of published cases of prolymphocytic leukemia (PLL) have been of B-cell origin. Nineteen cases of PLL of T-cell type have been described, as has a single case of PLL having a surface phenotype with features of both B-cells and T-cells. This report presents a review of these cases and comparison with one case of T-cell PLL. By using specific monoclonal antibody technique, this case was subcategorized into helper-cell phenotype: E-rosette(+), SIG(-), Anti-T(+), Anti-B(-), Anti-monocyte(-), OKT3(+), OKT4(+), OKT6(-), OKT8(-), Ia(+), and Tdt(-). Cytochemical studies showed paranuclear acid phosphatase granules. Postmortem examination revealed a predominant T-cell zone infiltration by the leukemic cells in the spleen and lymph nodes, with involvement of multiple organs. The application of the monoclonal antibody technique, which can be standardized among different laboratories to subclassify lymphoproliferative disorders into functional subtypes, should lead to a better understanding and more effective treatment of this disease.

T-cell prolymphocytic leukemia. Clinical and immunologic characterization

The clinical course of a patient with extensive skin involvement due to T-cell prolymphocytic leukemia is described. The malignant cells isolated from the patient's blood and skin were studied utilizing cytochemical analysis and multiple monoclonal antibodies directed against cell surface antigens. The leukemic cells displayed a surface antigen phenotype similar to that of normal post thymic suppressor T-cells. On the basis of this study together with the few published reports, it appears that T-prolymphocytic leukemia is derived from lymphocytes demonstrating either the suppressor or helper phenotype, and that extensive dermal infiltration may be independent of phenotypic classification. Although T-prolymphocytic leukemia shares certain morphologic, cytochemical, and immunologic features with chronic lymphocytic leukemia, it is an aggressive disease with an average survival of approximately 6 months and is best thought of as a distinct pathologic entity.

Subtypes of T-cell chronic lymphatic leukemia

Thirteen cases of T-cell chronic lymphatic leukemia (T-CLL) (including T-cell prolymphocytic leukemia) are presented. Five subtypes were distinguished according to morphologic and functional parameters of the leukemic cells: prolymphocytic; lymphocytic, small; lymphocytic, Sézary-like; lymphocytic, abundant cytoplasm; lymphocytic, abundant cytoplasm and granules. The subtype can be recognized by light and by electron microscopic investigation. Cytochemistry (APh and ANAE) may be helpful to delimit T-CLL from B-CLL, and acid phosphatase to recognize the subtype characterized by abundant cytoplasm and granules. Membrane marker investigations support the diagnosis of T-type CLL. When functional properties of the leukemic cells were tested, cells of one patient (T-PLL) were shown to help in B-lymphocyte differentiation and Ig-secretion, whilst the cells of a second patient (lymphocytic, abundant cytoplasm and granules) were proven to act as effectors in natural killing and antibody-dependent cytotoxicity. The T-helper lymphocyte nature of some of the leukemic cells was supported by demonstration of the Fc mu-receptor in three cases. In one of these patients, monoclonal IgM was detected in the serum. Response to therapy and prognosis were rather poor in this limited number of patients when compared with B-CLL.

Surface IgM kappa of prolymphocytic leukaemia cells with antibody activity to surface antigens of sheep and guinea-pig red blood cells

The immunological findings of a B-cell prolymphocytic leukaemia forming spontaneous rosettes with sheep (SRBC) and guinea-pig red blood cells (GPRBC) are reported. The B-cell lineage was revealed by Ia-like antigen, surface IgM kappa and lack of cytotoxicity of anti-human T-cell serum. Despite B-cell characteristics, prolymphocytes formed spontaneous rosettes with SRBC. Inhibition procedures demonstrated rosette formation to be the result of antibody activity of surface IGM to SRBC and GPRBC. Pretreatment of prolymphocytes with pronase or antibodies to mu or kappa-chains inhibited rosette formation. Furthermore, pre-treatment of SRBC with the patient's serum or IgM decreased rosette formation demonstrating circulating antibodies to antigen(s) of SRBC. Antigen(s) on SRBC and GPRBC are not related to Forssman or Paul Bunnel antigen.

Prolymphocytic leukemia: flow microfluorometric, immunologic, and cytogenetic observations

Cells isolated from four patients with prolymphocytic leukemia were evaluated by surface markers, cytogenetics, and flow microfluorometric analysis of cell size and DNA content. All four patients had B-cell markers with a high density of IgM, kappa type, and Ia-like antigen. Less intense staining for surface IgD was also observed. In each patient studied, chromosomal modes were in the hypodiploid or near-diploid range. Despite the karyotypic abnormalities, the cellular DNA content, as determined by flow microfluorometry, was within the normal limits in all cases. This suggests that the variability in chromosome numbers seen in these patients may reflect an abnormality in DNA package rather than differences in total DNA content. The modal electronic cell size of the prolymphocytes, determined by light scatter, was readily distinguishable from that of normal peripheral blood lymphocytes and the lymphocytes of chronic lymphocytic leukemia. Fewer than 4% of the peripheral prolymphocytes had S-phase DNA content, a finding consistent with the chronic nature of this leukemia.

Lysosomal enzyme activities in a case of T-cell chronic lymphocytic leukaemia

This study indicated that (i) high levels of N-acetyl-beta-glucosaminidase and beta-glucuronidase could be demonstrated cytochemically in T-CLL lymphocytes, and (ii), the biochemical activities of both enzymes were significantly increased in T-CLL lymphocytes compared with B-CLL lymphocytes. It would appear that the biochemical and cytochemical determination of these lysosomal enzyme activities offers an additional means of distinguishing T-CLL and B-CLL lymphocytes.

Isoenzymatic study of leucocytic acid phosphatase in haematologic diagnosis

Isoenzymatic study of leucocytic acid phosphatase under normal conditions identifies 3 isoenzymatic bands, which exhibit a noticeable cell specificity. Band 2 is granulocytic, band 3 lymphocytic and band 4 monocytic in origin. Pathologic deviations in the isoenzymatic pattern are both qualitative and quantitative. For some diseases such as chronic lymphocytic leukaemia there is a well-defined, differential pattern according to immunological B- or T-cell origin. The more significant qualitative aspects are related to the appearance of abnormal bands, especially band 3b, indicating blastic cellularity, and 5, corresponding to hairy cells. The isoenzymatic analysis of acid phosphatase activity is a simple haematologic complementary test, particularly useful in the differential diagnosis of lymphoproliferative disorders with peripheral blood manifestations.