Expression of killer cell inhibitory receptors is restricted to true NK cell lymphomas and a subset of intestinal enteropathy-type T cell lymphomas with a cytotoxic phenotype

Cellular Origins and Pathogenesis of Gastrointestinal NK- and T-Cell Lymphoproliferative Disorders

The intestinal immune system, which must ensure appropriate immune responses to both pathogens and commensal microflora, comprises innate lymphoid cells and various T-cell subsets, including intra-epithelial lymphocytes (IELs). An example of innate lymphoid cells is natural killer cells, which may be classified into tissue-resident, CD56bright NK-cells that serve a regulatory function and more mature, circulating CD56dim NK-cells with effector cytolytic properties. CD56bright NK-cells in the gastrointestinal tract give rise to indolent NK-cell enteropathy and lymphomatoid gastropathy, as well as the aggressive extranodal NK/T cell lymphoma, the latter following activation by EBV infection and neoplastic transformation. Conventional CD4+ TCRαβ+ and CD8αβ+ TCRαβ+ T-cells are located in the lamina propria and the intraepithelial compartment of intestinal mucosa as type 'a' IELs. They are the putative cells of origin for CD4+ and CD8+ indolent T-cell lymphoproliferative disorders of the gastrointestinal tract and intestinal T-cell lymphoma, NOS. In addition to such conventional T-cells, there are non-conventional T-cells in the intra-epithelial compartment that express CD8αα and innate lymphoid cells that lack TCRs. The central feature of type 'b' IELs is the expression of CD8αα homodimers, seen in monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), which primarily arises from both CD8αα+ TCRαβ+ and CD8αα+ TCRγδ+ IELs. EATL is the other epitheliotropic T-cell lymphoma in the GI tract, a subset of which arises from the expansion and reprograming of intracytoplasmic CD3+ innate lymphoid cells, driven by IL15 and mutations of the JAK-STAT pathway.

CD94 expression patterns in reactive and neoplastic T-cell and NK-cell proliferations

Lymphomas and leukemias of T-cell and NK-cell lineages are highly heterogeneous disorders and lack effective therapeutic strategies. Targeted therapies including anti-CD94 agents are currently under clinical investigation, but studies of CD94 expression on mature T/NK-cell neoplasms are limited. In this study, we investigated the landscape of CD94 protein expression in 15 patients with reactive T/NK-cell proliferations and 124 patients with various T/NK cell neoplasms. CD94 expression was detected at a high level in reactive NK-cells, with a lower level of expression in a subset of reactive CD8 + T-cells; reactive CD4 + T-cells were negative for CD94 expression. All NK-cell neoplasms surveyed had high-level CD94 expression, which was significantly higher than that in T cell neoplasms (p = 0.0174). In neoplastic T-cell proliferations, CD94 expression was positive in all 10 hepatosplenic T-cell lymphoma cases tested, with a high mean fluorescence intensity. Fifty-six percent of T-cell large granular lymphocytic leukemia cases were positive for CD94 expression in a subset of neoplastic cells. All T-cell prolymphocytic leukemia and 97 % of peripheral T-cell lymphoma cases showed no CD94 expression. Our findings demonstrate a broad range of CD94 expression among T/NK-cell neoplasms, in some at levels that suggest therapeutic vulnerability to CD94-targeted therapies.

Innate Immune Responses to Highly Pathogenic Coronaviruses and Other Significant Respiratory Viral Infections

The new pandemic virus SARS-CoV-2 emerged in China and spread around the world in <3 months, infecting millions of people, and causing countries to shut down public life and businesses. Nearly all nations were unprepared for this pandemic with healthcare systems stretched to their limits due to the lack of an effective vaccine and treatment. Infection with SARS-CoV-2 can lead to Coronavirus disease 2019 (COVID-19). COVID-19 is respiratory disease that can result in a cytokine storm with stark differences in morbidity and mortality between younger and older patient populations. Details regarding mechanisms of viral entry via the respiratory system and immune system correlates of protection or pathogenesis have not been fully elucidated. Here, we provide an overview of the innate immune responses in the lung to the coronaviruses MERS-CoV, SARS-CoV, and SARS-CoV-2. This review provides insight into key innate immune mechanisms that will aid in the development of therapeutics and preventive vaccines for SARS-CoV-2 infection.

Nasal-type extranodal natural killer/T-cell lymphoma presenting with a mass on the buttock: A case report

RATIONALE

Nasal-type extranodal natural killer (NK)/T-cell lymphoma is a highly unusual disease with no standard curative managements yet. Our focus is to emphasize a very rare case of nasal-type extranodal NK/T-cell lymphoma with onset of the mass on the buttock successfully operated by combination of surgical excision together with chemotherapy. The management of these unique cases is of great clinical guiding significance.

PATIENT CONCERNS

A 20-year-old woman presented with a 2-month history of continuous and progressive severe pain on her left buttock. Since December 2017, the patient developed nasal congestion, accompanied with mild pain in the left eye, and new subcutaneous nodules on both cheeks.

DIAGNOSIS

Postoperative pathology confirmed the diagnosis of extranodal NK/T cell lymphoma. This is an extremely rare presentation of nasal-type NK/T-cell lymphoma.

INTERVENTIONS

The patient underwent enlarged resection of the tumor on the buttock. After the diagnosis of extranodal NK/T-cell lymphoma was established, the patient received chemotherapy and autologous hematopoietic stem cell transplantation.

OUTCOMES

The patient's symptoms improved significantly after the surgery, and the postoperative period was uneventful at the 1-year follow-up visit. There were no complications associated with the operation and adjuvant therapies during the follow-up period.

LESSONS

Taken together, the lesion's clinical features, imaging results, and pathological characteristics are unique. Extranodal NK/T-cell lymphoma, although rare, should be part of the differential diagnosis when the patient presents with the mass on the buttock. We recommend enlarged excision of the extranodal lymphoma. Combined of surgical excision of the extranodal lymphoma, chemotherapy and autologous hematopoietic stem cell transplantation are good choice for proper treatment.

NKp46 is a diagnostic biomarker and may be a therapeutic target in gastrointestinal T-cell lymphoproliferative diseases: a CELAC study

OBJECTIVES

Primary GI T-cell lymphoproliferative diseases (T-LPD) are heterogeneous entities, which raise difficult diagnosis and therapeutic challenges. We have recently provided evidences that lymphomas complicating coeliac disease (CD) arise from innate-like lymphocytes, which may carry NK receptors (NKRs).

DESIGN

NKRs expression was compared by flow cytometry in intraepithelial lymphocytes (IEL) from CD, type I or type II refractory CD (RCD). NKp46 was next assessed by immunohistochemistry in paraffin-embedded biopsies from 204 patients with CD, RCDI, RCDII or GI T-cell lymphomas and from a validation cohort of 61 patients. The cytotoxic properties of an anti-NKp46 monoclonal antibody conjugated to pyrrolobenzodiazepine (PBD) was tested ex vivo in human primary tumour cells isolated from fresh duodenal biopsies.

RESULTS

NKp46 (but not CD94, NKG2A, NKG2C, NKG2D) was significantly more expressed by malignant RCDII IEL than by normal IEL in CD and RCDI. In paraffin biopsies, detection of >25 NKp46+ IEL per 100 epithelial cells discriminated RCDII from CD and RCDI. NKp46 was also detected in enteropathy-associated T-cell lymphomas (EATL, 24/29) and in monomorphic epitheliotropic intestinal T-cell lymphomas (MEITL, 4/4) but not in indolent T-LPD (0/15). Treatment with anti-NKp46-PBD could efficiently and selectively kill human NKp46+ primary IEL ex vivo.

CONCLUSION

NKp46 is a novel biomarker useful for diagnosis and therapeutic stratification of GI T-LPD. Strong preclinical rationale identifies anti-NKp46-PBD as a promising therapy for RCDII, EATL and MEITL.

Expression of activating natural killer-cell receptors is a hallmark of the innate-like T-cell neoplasm in peripheral T-cell lymphomas

Peripheral T‐ or natural killer (NK)‐cell lymphomas are rare and difficult‐to‐recognize diseases. It remains arduous to distinguish between NK cell‐ and cytotoxic T‐lymphocyte‐derived lymphomas through routine histological evaluation. To clarify the cells of origin, we focused on NK‐cell receptors and examined the expression using immunohistochemistry in 22 cases with T‐ and NK‐cell neoplasms comprising angioimmunoblastic T‐cell lymphoma, anaplastic lymphoma kinase (ALK)‐positive and ‐negative anaplastic large‐cell lymphomas, extranodal NK/T‐cell lymphoma, nasal type, monomorphic epitheliotropic intestinal T‐cell lymphoma, aggressive NK‐cell leukemia, and other peripheral T‐cell lymphomas. Inhibitory receptor leukocyte immunoglobulin‐like receptor subfamily B member 1 (LILRB1) was detected in 14 (64%) cases, whereas activating receptors DNAM1, NKp46, and NKG2D were expressed in 7 (32%), 9 (41%), and 5 (23%) cases, respectively. Although LILRB1 was detected regardless of the disease entity, the activating NK‐cell receptors were expressed predominantly in TIA‐1‐positive neoplasms (DNAM1, 49%; NKp46, 69%; and NKG2D, 38%). In addition, NKp46 and NKG2D were detected only in NK‐cell neoplasms and cytotoxic T‐lymphocyte‐derived lymphomas including monomorphic epitheliotropic intestinal T‐cell lymphoma. One Epstein‐Barr virus‐harboring cytotoxic T‐lymphocyte‐derived lymphoma mimicking extranodal NK/T‐cell lymphoma, nasal type lacked these NK‐cell receptors, indicating different cell origin from NK and innate‐like T cells. Furthermore, NKG2D expression showed a negative impact on survival among the 22 examined cases, which mainly received the standard chemotherapy regimen (log‐rank test, P = .024). We propose that the presence of activating NK‐cell receptors may provide new insights into understanding peripheral T‐cell lymphomas and characterizing them as innate‐like T‐cell neoplasm.

Emerging insights on the pathogenesis and treatment of extranodal NK/T cell lymphomas (ENKTL)

Extranodal NK/T-cell lymphoma (ENKTL) is a rare aggressive extranodal non-Hodgkin lymphoma (NHL) universally associated with Epstein-Barr virus (EBV). ENKTL most commonly occurs in non-elderly immune competent males in Asia and South America. A number of antecedent lymphoproliferative disorders (LPDs) have been described in Asian and South American patients, but the majority of Caucasian ENKTL patients have no known preceding LPD or underlying immunodeficiency. Other than EBV, no environmental or extrinsic factor has been implicated in oncogenesis. The precise mechanisms by which EBV infects NK or T cells and the virus' role in the pathogenesis of ENKTL have not been fully deciphered. However, a number of recent discoveries including disturbances in cell signaling and mutations in tumor suppressor genes have been identified, which are providing insights into the pathogenesis of ENKTL. In this review, we highlight the molecular, viral, and genetic underpinnings of ENKTL and discuss potential therapeutic implications.

Extranodal NK/T cell lymphoma and aggressive NK cell leukaemia: evidence for their origin on CD56+bright CD16-/+dim NK cells

Mature natural killer (NK) cell neoplasms are classified by the World Health Organization into extranodal NK/T cell lymphoma, nasal type (ENKTL) and aggressive NK cell leukaemia (ANKL). In order to propose their normal NK cell counterparts, we reviewed the literature on the phenotype of the neoplastic NK cells from five series of patients with ENKTL (n = 411) and seven series of patients with ANKL (n = 114) and compared with that of the normal and activated mature CD56 NK cell subsets. The tumour NK cells usually express brightly the CD56 adhesion molecule and CD94 lectin type killer receptor, and have an activation-related (cytoplasmic CD3ε, CD7, CD45RO, HLA-DR) phenotype; in contrast, CD16 and killer immunoglobulin-like receptors are frequently negative, and CD57 expression is almost never observed. These phenotypic features would suggest that ENKTL and ANKL cells do represent the neoplastic counterpart of the mature CD56 NK cells, which undergo activation and malignant transformation after Epstein-Barr virus infection.

KIR genotype distribution among Lebanese patients with Hodgkin's lymphoma

Introduction

In addition to their important role in fighting infection, natural killer cells are cytotoxic to cancer cells. Studies demonstrated that some KIR genes were responsible for the reduction of the risk of Hodgkin's lymphoma (HL) while others were associated with an increased risk of HL.

Aim

The aim of this study is to assess KIR genotypic distribution in Lebanese patients with Hodgkin's lymphoma.

Methods

KIR genotype was analyzed in 41 HL patients and 120 healthy Lebanese individuals using the KIR Genotyping SSP kit.

Results

No significant association between HL and any KIR gene was found. Among HL patients, the AA, AB, and BB genotype frequencies were, respectively, 41.46%, 43.9% and 14.63% with an A:B ratio of 1.73:1. As for the controls, the AA, AB, and BB genotype frequencies were, respectively, 39.17%, 50%, and 10.83% with an A:B ratio of 1.79:1.

Conclusion

In this first study from the Mediterranean region, KIR genotype does not seem to be associated with Hodgkin's lymphoma. Further clinical and translational research is needed to rule out the protective or predisposing role of KIR genes in this important clinical entity.

•

KIR genotyping has been implicated in a variety of clinical and immunological disorders.

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This is the second international but first Mediterranean paper describing KIR genes prevalence in Hodgkin’'s lymphoma.

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Results were compared to a control sample and confirmed the negative association between KIR genes and Hodgkin’s lymphoma

Aggressive mature natural killer cell neoplasms: report on a series of 12 European patients with emphasis on flow cytometry based immunophenotype and DNA content of neoplastic natural killer cells

We report 12 cases of aggressive natural killer (NK) cell neoplasms diagnosed in Portugal, with emphasis on flow cytometry. Ten patients had extranodal NK/T cell lymphoma, nasal type and two had aggressive NK cell leukemia, and seven were men and five were women, with a median age of 50 years. NK cells brightly expressed the CD56 adhesion molecule and CD94 lectin type killer receptor and had an activation-related HLA-DR+ CD45RA+ CD45RO+ immunophenotype, in most cases. In contrast, dim CD16 expression was found in a minor proportion of cases, whereas CD57 and the CD158a and CD158e1 killer immunoglobulin-like receptors were negative. One-third of cases showed a hyperploid DNA content and nearly all had a very high S-phase proliferative rate. The phenotypic features of the neoplastic NK cells would suggest that they represent the transformed counterpart of the CD56 + bright NK cells that circulate in normal blood.

Aggressive mature natural killer cell neoplasms: from epidemiology to diagnosis

Mature natural killer (NK) cell neoplasms are classified by the World Health Organization into NK/T cell lymphoma, nasal type (NKTCL), aggressive NK-cell leukemia (ANKCL) and chronic lymphoproliferative disorders of NK-cells, the latter being considered provisionally. NKTCL and ANKCL are rare diseases, with higher prevalence in Asia, Central and South America. Most NKTCL present extranodal, as a destructive tumor affecting the nose and upper aerodigestive tract (nasal NKTCL) or any organ or tissue (extranasal NKTCL) whereas ANKCL manifests as a systemic disease with multiorgan involvement and naturally evolutes to death in a few weeks. The histopathological hallmark of these aggressive NK-cell tumors is a polymorphic neoplastic infiltrate with angiocentricity, angiodestruction and tissue necrosis. The tumor cells have cytoplasmatic azurophilic granules and usually show a CD45(+bright), CD2(+), sCD3(-), cytCD3epsilon(+), CD56(+bright), CD16(−/+), cytotoxic granules molecules(+) phenotype. T-cell receptor genes are in germ-line configuration. Epstein-Barr virus (EBV) -encoded membrane proteins and early region EBV RNA are usually detected on lymphoma cells, with a pattern suggestive of a latent viral infection type II. Complex chromosomal abnormalities are frequent and loss of chromosomes 6q, 11q, 13q, and 17p are recurrent aberrations. The rarity of the NK-cell tumors limits our ability to standardize the procedures for the diagnosis and clinical management and efforts should be made to encourage multi-institutional registries.

Natural Killer Cell Immunoglobulin-like Receptor (KIR) genotypes in Follicular Lymphoma patients: results of a pilot study

AIMS

The Natural Killer Cell Immunoglobulin-like Receptor (KIR) genotype profiling in Follicular Lymphoma has not been reported before in the literature.

MATERIALS AND METHODS

DNA extracted from 20 Follicular Lymphoma patients and 62 healthy controls was analyzed for KIR genotyping using a polymerase chain reaction/sequence specific primers technique (PCR/SSP) for the presence of 16 KIR gene and pseudogene loci.

RESULTS

The AA, AB, and BB genotype frequencies were, respectively, 20%, 60% and 20% with an A:B ratio of 1:1. KIR 2DL4, KIR 3DL2, KIR 3DL3, and KIR 3DP1*003 were presented in all individuals. No significant difference between patients and controls was detected.

CONCLUSION

KIR genotyping profile does not seem to be associated with Follicular Lymphoma. The results presented in this pilot research represent the first international report about this important clinical entity.

Enteropathy-Type T-Cell Lymphoma Expressing NK-Cell Intraepithelial Lymphocyte (NK-IEL) Phenotype

Enteropathy-type T-cell lymphoma (ETL) is an intraepithelial T-lymphocyte (T-IEL) tumor. The tumor cells are usually CD3+, CD4-, CD8+, and contain cytotoxic granule associated proteins. We report on a CD3-negative CD56-positive enteropathy-associated lymphoma (ETL). This is the first case report of CD3-negative, CD56-positive, CD94-negative, and CD161-positive ETL. ETL cells originate from intraepithelial T-lymphocytes of the intestine. CD3-negative intraepithelial lymphocytes are known as natural killer (NK)-IELs. The phenotype of NK-IELs is also CD3-negative, CD56-positive, CD94-negative, and CD161-positive, while most normal NK cells express CD56 and CD94. CD3-negative lymphoma cells in this report also expressed CD56 and CD161, but not CD94. Because Southern blotting analysis showed a rearrangement of T-cell receptor (TCR) Cbeta in this case, the tumor is classified as an ETL. Based on the findings, NK-IELs may originate from T-cells, not NK-cells.

Intestinal T-cell and natural killer-cell lymphomas in Taiwan with special emphasis on 2 distinct cellular types: natural killer-like cytotoxic T cell and true natural killer cell

Primary intestinal lymphomas are rare, especially the T-cell and natural killer (NK)-cell types. Enteropathy-type T-cell lymphoma (ETL) is the most characteristic of the intestinal T-cell and NK-cell lymphomas (ITNKLs) defined in the World Health Organization classification. However, typical ETL is rare in nonendemic areas for celiac disease, which include Taiwan. With the exception of ETLs, ITNKLs comprise heterogeneous subtypes such as anaplastic large cell lymphoma, nasal-type NK/T-cell lymphoma and peripheral T-cell lymphoma, unspecified. Furthermore, the literature results with respect to the association between Epstein-Barr virus (EBV) and ITNKL are contradictory. To define the clinicopathological features of primary ITNKLs and develop a better understanding of their relationship with EBV in Taiwan, therefore, we investigated a sample of 11 patients based on the new World Health Organization classification using immunostaining, in situ hybridization for EBV detection, and polymerase chain reaction (PCR) for evaluation of T-cell receptor clonality. In conclusion, 2 distinct groups of primary ITNKLs were identified in our Taiwanese sample. The 6 group A cases were non-EBV-associated ETLs, prevalent in the jejunum and/or ileum. They were composed of monotonous round-ovoid medium-sized nuclei and had little pale cytoplasm. The immunophenotypes of these tumors were consistently CD3+, CD4-, CD8+, CD56+, T-cell intracellular antigen 1+, and Epstein-Barr early region- and monoclonal for T-cell receptor PCR, which indicated NK-like cytotoxic T-cell origin. The 5 group B cases were EBV-associated nasal-type NK/T-cell lymphomas prevalent in the ileum or cecum of younger patients. The neoplastic cells had polymorphous medium to large angulated nuclei and moderate cytoplasm, with immunologic phenotypes of CD4-, CD8-, variable cytoplasmic CD3varepsilon+, CD56+, T-cell intracellular antigen 1+, and Epstein-Barr early region 1+, and germ line PCR result for T-cell receptor, which indicated true NK-cell origin. The grave prognoses for the 2 groups did not differ significantly.

KIR gene in ethnic and Mestizo populations from Mexico

Killer cell immunoglobulin-like receptors are characterized by their great diversity of genes and alleles. Population studies have identified the presence of a broad variety of genotypes. In Mexico, there are diverse ethnic groups representing 9% of the total population and the rest is composed of Mestizos with a more varied biology. For the purpose of this study, genotyping was performed in Mestizos, in Mexico City inhabitants, and in three ethnic groups. The frequencies of genes KIR2DL2, 2DL5, 2DS1-3, 2DS5, and 3DS1 showed a greater variability in the groups studied. A total of 12 different genotypes were identified, the higher number for the Mestizos and the lower number for the Tarahumaras. Genotype 1 was found at a greater frequency in all the groups, except for the Tarahumaras, in which genotype 4 was more frequent. The frequency of genotypes 4 and 8 in Mexicans was higher than that for other populations analyzed. By subtyping of KIR3DL1, 3DL2, 2DL1, and 2DL3, two B haplotypes were identified in families; both were absent in Caucasian families. Our results indicated a greater diversity of genes in the Mestizos group than in the ethnic groups.

Malignant complications of coeliac disease

Patients with coeliac disease (CD), particularly those who are undiagnosed or do not adhere to a strict gluten free diet (GFD), are prone to develop complications. Malignant complications are the most serious and should be suspected when expected responses to GFD are not achieved or sustained. Lymphomas, mostly T-cell type, and other malignant tumours, particularly carcinoma of the small bowel, less frequently of stomach and oesophagus, are associated with CD. Loss of response to a gluten free diet (refractory coeliac disease) and ulcerative jejunitis are two recently described complications of CD that may progress to an Enteropathy-Associated T-cell Lymphoma (EATL). Coeliac disease-related lymphoma most often appears at extra-nodal sites, essentially the small bowel, although one have to realise that T-cell lymphomas arising in sites outside the small bowel could be related to coeliac disease. Workup of an EATL must include immunehistology and if necessary T-cell flow cytometry and T-cell rearrangement. Adequate imaging with CT and PET-scanning is mandatory.

Expression of CD158b on Peripheral Blood Lymphocytic Cell After Kidney Transplantation

OBJECTIVE

To investigate the expression of CD158b on peripheral blood lymphocytes after kidney transplantation.

METHODS

Sixty two kidney transplant patients were divided into two groups (normal group and rejection group) according to pathologic results and clinical situation. Blood samples were assessed for percentage of CD3+; CD19+; CD3-CD16/56+; CD3+CD158b+; CD19+CD158b+, and CD3-CD16/56+CD158b+ subsets.

RESULTS

The percentages of CD3+ cells preop as well as at 1 and 7 postoperative and the day acute rejection happened were 60.06 +/- 4.67, 40.43 +/- 4.11, 31.67 +/- 4.04, and 39.21 +/- 5.20, respectively. The percentages of CD3-CD16/56+ were 21.65 +/- 1.79, 33.84 +/- 5.45, 38.10 +/- 4.86, and 39.53 +/- 4.80, respectively. The percentages of CD3+CD158b+ were 1.46 +/- 0.31, 1.88 +/- 0.70, 2.03 +/- 1.04, and 0.65 +/- 0.12, respectively. The percentages of CD3-CD16/56+CD158b+ were 5.87 +/- 1.24, 3.57 +/- 0.57, 2.82 +/- 0.45, and 1.60 +/- 0.33, respectively.

CONCLUSIONS

The percentage of CD3+ cells in the normal and the rejection groups decreased significantly. The percentages of CD158b+T cells decreased significantly after acute rejection. The percentage of CD158b+NK cells decreased significantly after kidney transplantation, decreasing gradually after acute rejection. The percentage of CD158b+ total T cells decreased significantly following acute rejection. The percentage of CD3-CD16/56+CD158b+ of total NK cells decreased significantly after kidney transplantation and after acute rejection. Because few factors interfere with the expression of CD158b on NK cells, monitoring of this marker may be accurate and sensitive.

CD94 transcripts imply a better prognosis in nasal-type extranodal NK/T-cell lymphoma

Transcription of natural killer (NK) cell antigen receptors (NKRs), such as CD94, NKG2, and killer immunoglobulin-like receptors (KIRs), is developmentally regulated and clonally distributed. We have shown a restricted KIR repertoire (rKIR-R) without monoclonal T-cell receptor rearrangement (mTCR-R) supports a NK lineage in nasal-type extranodal NK/T-cell lymphoma (NTENL) but does not correlate with clinical outcomes. Developing NK cells express first CD94, then NKG2A, NKG2E, and finally NKG2C. This sequence suggests an immature CD94- and a mature CD94+ subtype of NTENL. Using a rKIR-R without a mTCR-R as a criterion in 25 cases of NTENL, we confirmed a true NK lineage in 19 cases, including 10 CD94+ and 9 CD94- patients by reverse transcriptase-polymerase chain reaction (RT-PCR). Eight of the 10 CD94+ patients but only 2 of the 9 CD94- patients survived beyond 1 year (median survival, 60 months versus 10 months by Meier-Kaplan survival analysis, P =.026 by Cox F test). The remaining 6 patients had a rKIR-R plus a mTCR-R, suggesting mixed NK/T differentiation. They were CD94- by RT-PCR, found predominantly in young women, and had a median survival of 35 months. Thus, on the basis of the transcripts of NKRs, a division of NTENLs into CD94+, CD94-, and mixed NK/T types reflects a true biologic divergence with different clinical behaviors.

Natural killer cell neoplasms: a distinctive group of highly aggressive lymphomas/leukemias

Natural killer (NK) cell neoplasms, which include extranodal NK/T-cell lymphoma (nasal and extranasal) and aggressive NK cell leukemia, are generally rare, but they are more common in people of Oriental, Mexican and South American descent. These neoplasms are highly aggressive, and show a strong association with Epstein-Barr virus. Extranodal NK/T-cell lymphoma most commonly affects the nasal cavity and other mucosal sites of the upper aerodigestive tract. Patients present with nasal obstruction or midfacial destruction. Despite the early stage of disease at presentation, overall survival is poor. Patients with the extranasal form of the lymphoma often present with high-stage disease, commonly involving the skin, gastrointestinal tract, testis, and soft tissue, and the prognosis is even worse. Histologically, the lymphoma can show a broad cytologic spectrum, but apoptosis, necrosis, and angioinvasion are common. The most common immunophenotype is CD2(+), surface CD3(-), cytoplasmic CD3(+), CD56(+). Based on currently available data, treatment of nasal NK/T-cell lymphoma should consist of radiotherapy, with or without multiagent chemotherapy. More research is required to ascertain the role of high-dose chemotherapy with stem cell rescue and that of non-multidrug resistance-related chemotherapeutic agents. Aggressive NK cell leukemia affects younger patients, who present with poor general condition, fever, and disseminated disease; they often die within a short time from systemic disease or complications such as multi-organ failure. The peripheral blood and bone marrow show atypical large granular lymphocytes, which exhibit an immunophenotype similar to that of extranodal NK/T-cell lymphoma. Aggressive NK cell leukemia must be distinguished from T-cell large granular lymphocyte leukemia and indolent NK cell lymphoproliferative disorder, both of which are indolent.

Presence of restricted killer immunoglobulin-like receptor repertoire and monoclonal T-cell receptor gamma rearrangement as evidence of mixed NK/T-cell differentiation in a subset of sinonasal lymphomas

Most sinonasal lymphomas have a restricted killer immunoglobulin-like receptor (KIR) repertoire without a monoclonal T-cell receptor-gamma (TCR-gamma) rearrangement, implying an NK lineage. However, the lineage assignment of sinonasal lymphoma with a monoclonal TCR-gamma rearrangement is unclear because of its mixed NK/T phenotype. The possibility of a mixed NK/T lineage arises with the discovery of T cells with NK features, such as KIR(+) T cells or Valpha24(+) NKT cells. The former might transform into a T-cell lymphoma with both a monoclonal TCR-gamma rearrangement and a restricted KIR repertoire; the latter might give rise to a T-cell lymphoma with a monoclonal Valpha24 rearrangement and possibly a restricted KIR repertoire. To identify such mixed-lineage lymphomas, we undertook a survey of 15 consecutive sinonasal lymphomas and found six with both a restricted KIR repertoire and a monoclonal TCR-gamma rearrangement, consistent with KIR(+) T-cell lymphomas. Among these six cases, four female CD56(-)/CD44(-)/CD8(-)/CD45RO(+)/CD45RA(-) cases constituted a distinct group with a better prognosis than the rest of the male cases of sinonasal lymphomas. None of the six cases had a monoclonal Valpha24 repertoire, thus excluding a derivation from NKT cells. The predominance of KIR(+) T cells that normally function in chronic viral infections over Valpha24(+) NKT cells that typically recognize glycolipid antigens is consistent with the known association of Epstein-Barr virus infection with sinonasal lymphoma. The demonstration of mixed lineage in a mature lymphoid neoplasm is unusual and echoes the World Health Organization classification that placed NK-cell and T-cell lymphomas in a mixed group.

Natural killer cell immunoglobulin-like receptor (KIR) locus profiles in African and South Asian populations

Natural killer (NK) and some T cells express killer cell immunoglobulin-like receptors (KIRs), which interact with HLA class I expressed by target cells and consequently regulate cytolytic activity. The number of KIR loci can vary and so a range of genetic profiles is observed. We have determined the KIR genetic profiles from one African (n = 62) and two South Asian (n = 108, n = 78) populations. Several of the KIRs are present at significantly different frequencies between the two major ethnic groups (eg KIR2DS4 gene frequency 0.82 African, 0.47 S Asian. Pc < 1 x 10(-6)) and this is due to uneven distribution of two KIR haplotype families 'A' and 'B'. All three populations described here displayed a greater degree of diversity of KIR genetic profiles than other populations investigated, which indicates further complexity of underlying haplotypes; in this respect we describe two individuals who appear homozygous for a large deletion including the previously ubiquitous 2DL4. We have also reanalysed three populations that we studied previously, for the presence of a KIR which is now known to be an indicator of the 'B' haplotype. South Asians had the highest overall frequencies of all KIR loci characteristic of 'B' haplotypes (Pc < 0.0001 to < 0.004). Furthermore, gene frequency independent deviances in the linkage disequilibrium were apparent between populations.

CD8+ T cells in cutaneous T-cell lymphoma: expression of cytotoxic proteins, Fas Ligand, and killing inhibitory receptors and their relationship with clinical behavior

PURPOSE

We investigated the number, phenotype, and prognostic significance of CD8+ T cells in patients with mycosis fungoides (MF) and CD30- primary cutaneous large T-cell lymphoma (PCLTCL).

PATIENTS AND METHODS

Immunohistochemical stainings for CD8, granzyme B (GrB), T cell-restricted intracellular antigen (TIA-1), Fas ligand (FasL), and killer-cell inhibitory receptors (KIRs; CD95, CD158a, and CD158b) were performed on 83 first-diagnostic biopsy samples obtained from patients with plaque-stage MF (n = 42), tumor-stage MF (n = 20), and CD30- PCLTCL (n = 21).

RESULTS

Serial sections and double-staining experiments showed that the large majority of CD8+ T cells in MF and CD30- PCLTCL expressed TIA-1 and FasL, whereas only a minority expressed GrB, which suggested that these CD8+ T cells were partly activated cytotoxic T lymphocytes (CTLs). These CD8+ CTLs never or rarely expressed KIRs. This phenotype was a constant feature of CD8+ CTLs and did not alter with disease progression. In contrast, the median percentage of CD8+ CTLs in plaque-stage MF (22%), tumor-stage MF (7%), and CD30- PCLTCL (3%) differed significantly (P < .0001) and was associated with a significant decrease in 5-year survival. Also within the group of tumor-stage MF, a significant relation between CD8+ CTLs and survival was found. Multivariate analysis in the total group of MF demonstrated that both skin stage and percentage of CD8+ CTLs were independent parameters of survival.

CONCLUSION

Our results demonstrated that partly activated CD8+ CTLs were present in CTCL and that high proportions of these cells correlated with a better prognosis. This suggested that these CD8+ CTLs could play an important role in the antitumor response in these conditions.