Human NK cells in health and disease: clinical, functional, phenotypic and DNA genotypic characteristics

Uterine natural killer cells and recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA), termed as two or more consecutive pregnancy loss is a great problem for some women of childbearing age. A large number of evidence confirm that there may be an immune background of RSA. As a member of the innate immune system, uterine natural killer (uNK) cells account for about 70% of total lymphocytes during pregnancy and play a critical role in the establishment and maintenance of pregnancy. This review mainly introduces the phenotype, origin, receptor, and function of uNK cells to illuminate its relationship with RSA.

51Cr release assay of antibody-dependent cell-mediated cytotoxicity (ADCC)

Antibody-dependent cell-mediated cytotoxicity (ADCC) is an immunologic cytotoxic effector mechanism that is dependent on the cooperative interaction of humoral and cellular effector elements. This unit describes an assay of ADCC activity that can be used as a test for immunocompetence in effector cells or to test the activity of a monoclonal antibody to mediate ADCC. In this form of cytotoxicity, effector cells with receptors for the Fc portion of immunoglobulin produce target cell lysis by attachment to the Fc portion of antibodies that are bound to target cells via their antigen-combining sites. Therefore, an ADCC assay involves three essential components: labeled target cells, antibodies with specificity for target-cell surface antigens, and effector-cell populations. The basic protocol describes a method of measuring ADCC effector activity in lymphoid cells (peripheral blood mononuclear cells, or PBMC) that employs (51)Cr-labeled target cells. The three components are mixed in microtiter-plate wells and lysis of the target cells is detected by measuring the release of radioactivity into the cell supernatant. Support protocols describe procedures for preparing anti-target cell antiserum and (51)Cr-labeled target cells.

Blastic natural killer cell leukaemia in a dog--a case report

A case of canine non-T, non-B lymphoid leukaemia was determined to be of natural killer (NK) cell lineage by detecting specific expression of canine CD56 mRNA by reverse transcriptase polymerase chain reaction analysis. Although NK cells are usually considered to be morphologically large granular lymphocytes, the malignant NK cells in this case were agranular and blast-like, resembling human blastic NK cell leukaemia. The prognosis of human NK cell leukaemia is usually poor. In this case, the dog died 10 days after initial presentation, despite chemotherapy.

Clinical, hematologic, and immunophenotypic characterization of canine large granular lymphocytosis

Clinical, hematologic, and immunophenotypic data were studied in 25 dogs with large granular lymphocyte (LGL) lymphocytosis. Primarily large-breed dogs were affected, with an average age at initial diagnosis of 10 years (range 5-14 years). All dogs had persistent (>4 months) LGL lymphocytosis except for three that were euthanized with aggressive disease. Splenomegaly was reported in 12 of 20 dogs in which splenic size was evaluated. The clinical course was heterogeneous and dogs were divided into four groups based on similar clinical and hematologic findings: acute leukemia (3/25), persistent lymphocytosis with anemia (12/25), persistent lymphocytosis without anemia (8/25), and reactive lymphocytosis (2/25). Immunophenotypes varied within groups but were homogeneous among cells from the same patient except in the two dogs classified as reactive LGL lymphocytosis. Analysis of T-cell receptor (TCR) usage identified three main LGL lineages. TCRalphabeta was expressed in 15/25 (60%) cases. TCRgammadelta was expressed in 8/25 (32%) cases, and 2/25 (8%) cases were CD3-, compatible with NK cells. beta2 integrin expression was distinctive. CD11a was consistently expressed, while CD11b was absent. CD11c was expressed only weakly in 16/25 (64%) cases. The leukointegrin alphadbeta2 was highly prevalent on all LGL lineages, being expressed in 23/25 (92%) cases. Prominent involvement of the spleen, relative sparing of bone marrow, an unexpectedly large proportion of gammadelta T-cell LGLs, and the distinctive beta2 integrin expression pattern on diverse lineages of LGLs suggest the disease arises from unique populations of lymphocytes that preferentially localize in the splenic red pulp.

Malignant hematopoietic cell lines: in vitro models for the study of natural killer cell leukemia-lymphoma

Malignancies involving natural killer (NK) cells are rare disorders. The complexity of NK cell-involving disorders has only recently been appreciated. Modern classifications discern immature (precursor) from mature NK cell leukemias-lymphomas. Continuous NK leukemia-lymphoma cell lines represent important model systems to study these neoplasms. While there are a number of putative NK cell lines which are, however, either not characterized, not immortalized, non-malignant, non-NK, or plain false cell lines, six bona fide malignant NK cell lines have been established and are sufficiently well characterized: HANK1, KHYG-1, NK-92, NKL, NK-YS and YT. Except for YT which was derived from a not further defined acute lymphoblastic lymphoma, these cell lines were established from patients with various NK cell malignancies. Five of the six cell lines are constitutively interleukin-2-dependent. Their immunoprofile is remarkably similar: CD1-, CD2+, surface CD3 (but cytoplasmic CD3epsilon+), CD4-, CD5-, CD7+, CD8-, CD16-, CD56+, CD57-, TCRalphabeta-, TCRgammadelta-, negative for B cell and myelomonocytic markers. The immunoglobulin heavy chain and T cell receptor genes are all in germline configuration. All six lines show complex chromosomal alterations, with both numerical and structural aberrations, attesting to their malignant and monoclonal nature. Functionally, these cells which contain azurophilic granules in their cytoplasm are nearly universally positive in NK activity assays. Three of five cell lines are Epstein-Barr virus-positive (type II latency). The composite data on these six cell lines allow for the operational definition of a typical malignant NK cell line profile. NK leukemia-lymphoma cell lines will prove invaluable for studies of normal and malignant NK cell biology.

Immunohistochemical detection of cytotoxic lymphocytes in malignant serous effusions

The use of ancillary techniques to aid in the diagnosis of metastatic carcinoma in serous effusions has been the subject of numerous studies. In this article, we study 35 cases of malignant effusions (metastatic adenocarcinoma) and 20 benign effusions using a panel of immunohistochemical markers to determine whether changes in the subpopulations of accompanying lymphoid cells can be detected with this technique and whether such changes are associated with the presence of malignancy. We noted a significant increase in cytotoxic lymphocytes, defined as the percentage of all lymphoid cells staining with an antibody to TIA-1 (an antigen localized to the cytotoxic granule membranes of cytotoxic T cells and natural killer cells) in malignant compared with benign effusions (23% vs. 12%; P < 0.05). In addition, nearly all cases in which cytotoxic lymphocytes composed > 20% of the lymphoid cell population contained metastatic tumor. Thus, immunohistochemical staining for TIA-1 can reliably detect cytotoxic lymphocytes in cell blocks of serous effusions; in addition, a relative increase in their number is associated with the presence of malignancy.

Human myeloma cell apoptosis induced by interferon-alpha

Although there have been reports regarding the clinical effectiveness of IFN alpha in the treatment of myeloma patients during this decade, its biological effects on human myeloma cells have still not been clarified. Recently, apoptosis has been considered as one of the most important mechanisms in the programmed cell death of malignant tumour cells induced by chemotherapeutic agents or cytotoxic immunological defence in malignancy-carrying hosts. Among the several pathways which function to induce apoptosis, Fas and the Fas ligand system have been thought to play an important role in inducing tumour-cell apoptosis, particularly in immunological prevention. In this study we investigated myeloma cell apoptosis induced by IFN alpha using five human myeloma cell lines which were established without any additional supplementation of IL-6. In addition, the mRNA expression levels of apoptosis-related genes employing the reverse transcriptase-polymerase chain reaction (RT-PCR) were also analysed with the KMS-12-PE cell line, which was the most sensitive of the five cell lines in terms of apoptosis induced by IFN alpha. Based on the results, it was determined that IFN alpha induced myeloma cell apoptosis in a dose-dependent manner, but the sensitivity to IFN alpha in the cell lines examined varied and one cell line revealed growth stimulation by IFN alpha. In addition, the apoptosis induced by IFN alpha did not seem to be mediated by the Fas/Fas ligand pathway. Finally, the IL-6, IL-6R, IRF1 and IRF2 genes were up-regulated in KMS-12-PE cells cultured with IFN alpha. Therefore these genes may play an important role during apoptosis induced by IFN alpha.

Does 'healing' benefit patients with chronic symptoms? A quasi-randomized trial in general practice

This study was designed to examine the effects of a healer seeing chronically ill patients in a large semirural practice. The 57 patients were allocated alternately either to receive ten weekly healing sessions or to become waiting-list controls. Two weeks after completion of 'healing' 22 (81%) of the 27 study patients thought their symptoms had improved and 15 of these thought they had improved substantially. Study patients scored better than controls on both measures of symptoms (P < 0.05, P < 0.01), on anxiety and depression ratings (P < 0.01, P < 0.05) and on general function measured by the Nottingham Health Profile (P < 0.01). Treatment differences were still evident three months later for one of the measures of symptom change (P < 0.05) and for both anxiety and depression ratings (P < 0.01, P < 0.05). The percentages of natural killer cells (CD16, CD56) did not change greatly in either group. These results suggest that healing may be an effective adjunct for the treatment of chronically ill patients presenting in general practice. They do not distinguish between any specific effects of spiritual healing and non-specific effects such as relaxation; for further investigation, randomized controlled trials will be needed.

T-cell lymphoma associated with natural killer-like T-cell reaction

We report a case of T-cell lymphoma showing in the peripheral blood (PB) exclusively T-lymphocytes with suppresser T-cell preponderance and a high percentage of natural killer (NK) marker positive cells by flow cytometry. A T-cell receptor (TCR) gene analysis of the PB leukocytes demonstrated rearrangements of TCRalpha, TCRbeta, and TCRgamma genes. Therefore, the phenotype and genotype appeared to be consistent with an NK-like T-cell leukemia/lymphoma. However, when the PB lymphocytes were separated by size, it was found that 80% of NK marker positive cells were in the smaller cell population, while the neoplastic cells were in the large cell gate. A diagnosis of T-cell lymphoma with reactive NK-like T-cells was finally confirmed by demonstrating the presence of both large atypical lymphoid cells and large granular lymphocytes (LGL) on PB smears. Although immunoperoxidase stain of bone marrow and colon showed positive T-cell markers in the tumor cell population, cytoplasmic granules could not be identified in tissue sections and, thus, a distinction between T-cell lymphoma and NK-like T-cell lymphoma could not be made by light microscopy until NK markers were studied. CD57 was demonstrated immunohistochemically in small lymphocytes but not in the large tumor cells in the colon. Electron microscopy, however, demonstrated LGL reaction to the lymphoma cells in the colonic biopsy. NK-like T-cell lymphoma usually carries a poorer prognosis than peripheral T-cell lymphoma, thus the distinction of these neoplasms is important. This study emphasizes that T-cell lymphoma may cause an LGL reaction or proliferation. If the lymphoma cells were of the same size as LGL, flow cytometric studies may have misled the diagnosis to NK-like T-cell-lymphoma.

Bone marrow granulomas associated with chronic natural killer cell lymphocytosis

Two patients with chronic natural killer cell lymphocytosis (CNKL) and associated bone marrow granulomas (BMGs) are described. The increases in the peripheral blood of both the proportion (64 and 74%) and absolute number (2,000/microL and 4,700/microL) of NK cells have persisted for more than 1 and 3 years. One patient was asymptomatic with thrombocytopenia and neutropenia, and the other presented with fever of unidentified origin, which has since responded to a nonsteroidal anti-inflammatory agent. Bone marrow examination in both patients showed loose aggregates of epithelioid histiocytes similar to the noncaseating granulomas seen in other diseases. An unusual feature, however, was the presence of many scattered, large mononuclear histiocytes that were morphologically similar to atypical megakaryocytes. Extensive clinical and laboratory studies did not reveal an established cause for the BMGs. BMGs may be associated with CNKL, with the unusual feature of scattered, atypical mononuclear histiocytes.

Chronic natural killer cell lymphocytosis

Chronic proliferations of natural killer (NK) cells (CD3- CD16+) are identified initially by detecting large granular lymphocyte (LGL) excess in a peripheral blood smear and subsequent lymphocyte immunophenotyping by flow cytometry. A related disease, T-LGL leukemia, has an indolent clinical course with chronic neutropenia and a close association with rheumatoid arthritis. Herein are described the clinical presentation and long-term clinical course of patients with chronic NK cell lymphocytosis (CNKL). The majority of the 14 patients followed up for a median of 4 years presented with severe cytopenias or vasculitic syndromes that were responsive to immunosuppressive therapy. Other manifestations included fever and arthralgias. In general, the disease was nonprogressive and had a course similar to that of T-LGL leukemia.

Immunophenotype and DNA cell content in multiple myeloma

In this paper three different areas of the biology of multiple myeloma (MM) are reviewed: (1) the immunophenotypic characteristics of plasma cells (PC), (2) the changes in the immunoregulatory cells, and (3) the cell DNA content of PC. Myelomatous PC display a heterogeneous phenotype not only between different patients but also within each patient consistent with the fact that the neoplastic clone is able to undergo a certain degree of differentiation. In addition, PC generally lack surface B cell associated antigens and infrequently show reactivity for non-lineage restricted markers. The B-B4 and CD38 are the two best markers for identifying PC which are crucial for the correct assessment of other antigens by multiple staining procedures. Moreover, some of the antigens present in PC such as CD56, CD20, CD10, CD28 and SIg may have prognostic implications. Whether or not normal PC are phenotypically different from myelomatous PC remains controversial although some antigenic combinations such as CD19-/CD56++ could probably help to identify the malignant nature of PC. Both T and NK cells are markedly altered in MM patients probably reflecting a host-tumour immunological interaction. The reduction in CD4 cells correlates both with advanced clinical stage and poor survival. As far as NK cells are concerned, there is an overall increase in peripheral blood and BM in MM patients but the changes observed are heterogeneous, reflecting the existence of different NK cell subsets. This fact could explain the contradictory results observed in the literature. Accumulating evidence exists that the measurement of cell DNA content by flow cytometry is a useful parameter in the clinical evaluation of MM patients. Between 50 and 70% of MM patients display DNA aneuploidy with the majority of them hyperdiploid. Upon comparing hyperdiploid with diploid patients, the former usually display a better prognosis. The possibility of analysing the cell cycle distribution by using a PI/CD38 double staining technique may be an alternative to other more laborious methods of assessing the PC labelling index. In our experience, patients with > 3% S phase PC have an adverse prognosis and this parameter was the most important independent prognostic criteria for predicting survival.

Higher cytotoxic activity and increased levels of IL-1 beta, IL-6, and TNF-alpha in patients undergoing cardiopulmonary bypass

Extracorporeal circulation (EC) by surgical bypass is often associated with a systemic inflammatory response. The purpose of this study was to assess the effect of EC on the serum levels of pro-inflammatory mediators Interleukin (IL)-1 beta, IL-6, tumor necrosis factor (TNF)-alpha, and soluble CD-23. Peripheral blood lymphocyte subsets and natural killer cell (NK) cytotoxic activity were also analyzed before and after the bypass process. The results from eight patients who underwent cardiac surgery showed a significant increase in the levels of IL-1 beta, IL-6, and TNF-alpha, a decrease in CD4+/CD8+ lymphocyte ratio, and an overstimulated NK cytotoxic activity. These changes on serum cytokine levels and cellular immunology parameters could play an important role in the development of adverse effects associated with EC.

Recovery of natural killer cells after chemotherapy for childhood acute lymphoblastic leukemia and solid tumors

Recovery of natural killer (NK) cells after cessation of chemotherapy for childhood acute lymphoblastic leukemia (ALL) and solid tumors was investigated in 25 children aged 3 to 18 years. The numbers of CD3-CD56+, CD16+, and CD8-CD57+ cells in peripheral blood were analyzed with monoclonal antibodies and flow cytometry at 0, 1, 3, 6, 9, and 12 months after discontinuation of therapy. The CD3-CD56+ and CD16+ cell counts of ALL patients (n = 14) were below the mean -1 SD values of controls at cessation but normalized within one month due to a rapid 2.1 and 4.5 fold increase, respectively. The CD8-CD57+ cell count of ALL patients was normal compared to controls at cessation. In solid tumor patients (n = 11), the counts of all NK cell phenotypes studied were of normal amount compared to controls at cessation and no vigorous increase occurred after the therapy. NK cell function was determined by killing K 562 target cells in five patients. In the two standard risk ALL patients tested, the activity was still low at 5 months after therapy. In contrast, the function was normal at 1 month (Wilms' tumor), 3 months (Mb Hodgkin's) and 6 months (Burkitt lymphoma). In conclusion, NK cell counts were decreased compared to controls during therapy for ALL, but recovered rapidly afterwards. In spite of normal counts, NK cell function may be impaired for several months. The number and function of NK cells is less affected in solid tumor patients. These differences may reflect the milder immunosuppressive effect of interval cytostatic medication in solid tumor patients when compared to the more intensive continuous therapy in ALL patients.

Clonal CD3+CD8+ large granular lymphocyte (LGL)/NK-associated (NKa) expansions: primary malignancies or secondary reactive phenomena?

This study reports the clinical, haematological and immunophenotypic features of a series of 25 patients with clonal expansions of large granular lymphocytes (LGL)/NK-associated (NKa) cells. These showed a male predominance (16:9) with a median age of 67 (range 38-91) years; four had a documented history of rheumatoid arthritis, a further 18 had diverse clinical disorders, and the remaining three were clinically well. Mild anaemia was found in approximately half the patients and a lymphocytosis (seen in approximately 70% of the cases) was usually modest (< 10.0 x 10(9)/l). Neutropenia was the most frequently observed feature, and this was typically persistent in nature. Serum studies revealed few consistent features although positive rheumatoid factor and increased soluble CD8 levels were noted in 67% and 87% of those cases tested. Phenotypically, all cases were CD2+CD3+CD8+ and expressed membrane TCR alpha beta chains; most (17/22) were additionally CD5+ and (19/22) CD7+. The staining intensities of CD5 and CD7 antigens were however lower than that of normal CD4+ and CD8+ blood lymphocytes. Expression of NKa antigens was variable although 16/22 cases were CD16+CD56- and 19/22 were CD57+. Clonal CD3+CD8+ LGL/NKa expansions with a CD16+CD56+ composite phenotype were not seen in this patient series. Analyses of 'activation' antigens showed a consistent lack of CD25 expression by CD3+ cells, but increased CD3/Ia co-expression was found in a high proportion (19/25) of cases. Studies of CD45R isoform expression by CD8+ LGL/NKa cell fractions revealed a consistent CD45RA+RO- profile for all cases tested.(ABSTRACT TRUNCATED AT 250 WORDS)

A biclonal large granular lymphocyte (LGL)/NK-associated (NKa) disorder of CD4+ and CD8+ lymphocyte subpopulations characterized by the simultaneous presence of distinct TCR rearrangements

This communication reports a patient with concomitant expansions of CD4+ and CD8+ large granular lymphocytes. Immunological analyses revealed that the abnormally increased CD4+ LGL fraction was phenotypically similar to other reported persistent CD4+ LGL expansions, whereas the phenotypic profile for the CD8+ LGL component was unusual. Of particular note was the finding that both the CD4+ and CD8+ LGL fractions showed high membrane CD45RO isoform expression, thus suggesting their 'primed' status. Molecular biology studies of immunomagnetically fractionated cells using a T gamma 9 TCR gamma gene primer further revealed that the CD4+ and CD8+ components were both clonal but showed different patterns of rearrangement. It is suggested that the simultaneous presence of CD4+ and CD8+ clonal populations are unlikely to have been derived from a common progenitor and that they reflect expansions of functionally restricted subpopulations.

Persistent clonal expansions of CD3+TCR gamma delta+ and CD3+TCR alpha beta+CD4-CD8- lymphocytes associated with neutropenia

This communication reports the clinical and cellular features of five elderly female patients with persistent moderate to severe neutropenia and concomitant relative expansions of CD3+TCR gamma delta+ (n = 4) or CD3+TCR alpha beta+CD4-CD8- (n = 1) lymphocyte populations. In clinical terms, severe neutropenia was the main contributing factor to patient symptoms although two additionally had long-standing histories of rheumatoid arthritis. The absolute lymphocyte counts did not exceed the normal upper limit in these patients, and morphologically the lymphocytes were not typically of large granular lymphocyte (LGL) type although LGL-associated BLT-esterase staining was consistently increased. Expression of NK-associated (NKa) membrane determinants (CD16, CD56 and CD57) were variable but there was an apparent correlation between weak membrane CD8 and CD16 expression. DNA genotypic studies confirmed that the four CD3+TCR gamma delta+ cases were clonal in nature and add further support to an emerging impression that expansions of these lymphocyte subpopulations may frequently be clinically associated with autoimmune phenomena in general and neutropenia in particular.

Granular lymphocyte proliferative disorders: a multicenter study of 20 cases

A series of 20 patients with granular lymphocyte proliferative disorders (GLPD) is reported. The criterion of inclusion was presence of persistent (> or = 6 months) granular lymphocytosis in the absence of any causative illness. Diagnoses made upon analytical control in half the patients of splenomegaly (25%) and hepatomegaly (25%) were infrequent. Clinical course was nonprogressive in 17/20 patients, but two developed high-grade NHL several years later and one showed progressive disease. Actuarial probability of survival at 5 years was 85%. Granular lymphocyte morphology was relatively homogeneous, and peripheral blood counts were preserved in the most patients. Bone marrow lymphocytic infiltration was low, as assessed by bone marrow aspiration and/or biopsy. Eosinophilia was an outstanding feature in eight cases. Ultrastructurally, all cases showed parallel tubular arrays; cytoplasmic granules and numerous short microvilli were noticed. The lymphoid phenotype was heterogeneous, the most common being CD2+CD3+CD4-CD8+, but six patients (30%) were CD4+ with variable expression of natural killer-associated antigens. Chromosomal analysis was abnormal in 4/10 patients [trisomy 19, t(5;6); inv(14) and inv(10)]. The study of beta-chain of the T-cell receptor revealed clonal rearrangements in 14 (78%), restricted to CD3+ patients (92%). In vitro culture of myeloid precursors showed decreased CFU-GM in 5/6 patients. Virological studies for HTLV-I and II were negative. In conclusion, the presence of a clonal proliferation was not correlated with the clinical course or an associated disease.

A study of granular lymphoproliferative disorders including a CD3 negative case with a rearrangement of the T-cell receptor locus

The clinical, and laboratory features of 9 patients presenting with chronic proliferations of large granular lymphocytes (LGL) are described. The median patient age was 61 years (33-80) and median patient follow up was 3.5 years (28 mo-10 years) with all patients surviving. Clinical features and blood and bone marrow findings are documented. Immunophenotypic analysis showed lymphocytes from 4 patients were CD3 negative and 5 were CD3 positive with natural killer associated cell surface antigens expressed in both these groups. Analysis of the T-cell receptor (TCR) loci revealed a clonal rearrangement in 4 samples including one CD3 negative sample. Clonality did not correlate with immunophenotype or clinical or haematological features. We conclude that patients with persistent LGL have a wide diversity of cell surface marker expression and that whilst some patients with CD3 negative LGL proliferations have cells which are most likely of natural killer (NK) cell origin, in others TCR rearrangements can be demonstrated suggesting these cells are possibly of T-cell, not NK cell, origin.

Lymphoid subsets in acute myeloid leukemias: increased number of cells with NK phenotype and normal T-cell distribution

Natural killer (NK) and T subsets were analyzed with appropriate dual labeling by flow cytometry in peripheral blood (PB) (66 cases) and bone marrow (BM) (55 cases) from patients with de novo AML in order to determine: (a) their distribution at diagnosis, (b) the correlation between PB and BM in NK subpopulations, (c) their relationship with the clinical and hematological disease characteristics, and (d) the changes occurring upon achieving complete remission (CR). NK cells defined by the expression of CD56 in the absence of CD3 were significantly increased at diagnosis and their levels in PB correlated with those of BM. By contrast, NK subsets defined by CD16 expression (CD16+ CD2+ and CD16+ CD2- NK-cell subsets) as well as T lymphocytes with NK activity (CD56+ CD3+), although increased in PB, displayed normal levels in BM. An additional observation of interest was the expansion of an immature NK population lacking CD16 Ag expression (CD56+ CD16-). AML cases were divided into two groups according to the absolute number of NK cells in PB; patients with the highest levels showed an increased proportion of blast cells in PB (p = 0.01), monocytic subtypes (p = 0.03), and expression of CD11b, CD14, and CD4 antigens (p = 0.05). Infections at diagnosis were not related to the level of NK cells. In 19 patients who achieved complete remission the number of CD56+ CD3- cells tended to be reduced to within the normal range. Other T-cell populations, including the CD4 naive and memory cells, were also explored, their distribution being normal in the PB of AML patients. By contrast, the cytotoxic subset CD8+/CD57+ was significantly increased (p < 0.001). These data point to the existence of marked alterations of NK cells in AML patients, possibly reflecting a host-tumor immunological interaction.

Transient and persistent expansions of large granular lymphocytes (LGL) and NK-associated (NKa) cells: the Yorkshire Leukaemia Group Study

A survey of 870 different adult blood samples (primarily from patients with non-haematological disorders) found that 269 (31%) had increased proportions (> 25%) and/or absolute numbers (> 1.0 x 10(9)/l) of morphologically-defined large granular lymphocytes (LGL), and/or phenotypically-defined NK-associated (NKa) cells. Of these, 112 were re-analysed at least 6 months after initial presentation and were classified as 'persistent' (92/112) or 'transient' (20/112) according to whether or not the original abnormality was still present. Lymphocyte counts in most patients with persistent abnormalities were within normal limits (18/92) or slightly increased (68/92), with only six having a lymphocytosis exceeding 10.0 x 10(9)/l. With the exception of five persistent LGL expansions in which the granular lymphocytes did not express NKa determinants (designated LGL+NKa-), the remaining 87 cases could be phenotypically grouped according to their primary abnormality as CD8+NKa+ (n = 33), CD4+ NKa+ (n = 14), CD8dim+NKa+ (n = 7) or CD8-NKa+ (n = 33). TCR genotypic studies in 58 patients showed that the 16 patients with rearranged TCR components were restricted to the CD8+NKa+ group and that, in most of these, the CD8+ fraction showed abnormal relative CD16/CD56 expression. Persistent neutropenia (n = 15) also appeared to be associated with primary abnormalities of CD8+NKa+ cells (12/15), with 10 of these additionally showing rearranged TCR genes. In contrast, persistently increased CD8dim+NKa+ and CD8-NKa+ components did not appear to phenotypically differ from their corresponding 'counterparts' in normal bloods or in patients with transient LGL/NKa+ abnormalities. This survey has therefore established that persistent LGL/NKa+ abnormalities are considerably more common than suggested in published work, that a high proportion of patients with expanded CD8+NKa+ components, with quite diverse clinical histories, show evidence of clonal lymphoid populations, and that the clonal nature of such disorders appears to be associated with abnormal NKa phenotypic patterns.

A distinct large granular lymphocyte (LGL)/NK-associated (NKa) abnormality characterized by membrane CD4 and CD8 coexpression

In a study of 870 individual patients with either lymphocytosis (excluding known lymphoproliferative disease), increased proportions of blood lymphocytes with granular morphology (LGL), or neutropenia, 14 cases were found with abnormally increased CD3+CD4+CD8+ components. Eleven of these were further investigated and 10 shown in follow-up studies to be persistent in nature. Morphological assessments revealed increased LGL in 9/11 cases, and in seven of these > 50% lymphocytes had discernable cytoplasmic granulation. Immunophenotypic studies indicated that CD8 expression by CD4+ lymphocytes in these patients was of low density (CD8dim+), and that both the CD4+CD8- and CD4+CD8dim+ fractions in each patient was characterized by a CD11b+CD16-CD56+CD57+ composite NK-associated (NKa) phenotype (in contrast to normal CD4+CD8- blood lymphocytes and CD4+CD8+ thymocytes which were consistently CD11b-CD16-CD56-CD57-). TCR genotypic studies revealed rearranged components (beta plus gamma, or beta alone) in 5/11 cases, but there were no obvious relationships between TCR configuration (including rearranged band densities) and immunophenotypes, absolute lymphocyte or neutrophil numbers, the proportions of blood LGL, or the proportions of CD4+ cells coexpressing CD8. The occurrence of identical NKa phenotypic profiles in both germline and rearranged TCR cases does, however, suggest the possibility of an evolutionary process from a non-clonal expansion to a clonal state. Serum studies, including soluble CD4, CD8 and IL2-R concentrations and autoantibody investigations, of representative germline and rearranged TCR cases failed to indicate any consistent abnormalities, but there was some suggestion for the existence of a chronic reactive process in some of the patients with germline TCR. These findings suggest that expanded LGL/NKa+ components with phenotypic evidence of CD4/CD8 coexpression should be regarded as a distinct diagnostic category and that persistent CD4+CD8+ abnormalities with germline TCR should be monitored for possible clonal transition.