Proinflammatory S100 proteins regulate the accumulation of myeloid-derived suppressor cells

Chronic inflammation is a complex process that promotes carcinogenesis and tumor progression; however, the mechanisms by which specific inflammatory mediators contribute to tumor growth remain unclear. We and others recently demonstrated that the inflammatory mediators IL-1beta, IL-6, and PGE(2) induce accumulation of myeloid-derived suppressor cells (MDSC) in tumor-bearing individuals. MDSC impair tumor immunity and thereby facilitate carcinogenesis and tumor progression by inhibiting T and NK cell activation, and by polarizing immunity toward a tumor-promoting type 2 phenotype. We now show that this population of immature myeloid cells induced by a given tumor share a common phenotype regardless of their in vivo location (bone marrow, spleen, blood, or tumor site), and that Gr1(high)CD11b(high)F4/80(-)CD80(+)IL4Ralpha(+/-)Arginase(+) MDSC are induced by the proinflammatory proteins S100A8/A9. S100A8/A9 proteins bind to carboxylated N-glycans expressed on the receptor for advanced glycation end-products and other cell surface glycoprotein receptors on MDSC, signal through the NF-kappaB pathway, and promote MDSC migration. MDSC also synthesize and secrete S100A8/A9 proteins that accumulate in the serum of tumor-bearing mice, and in vivo blocking of S100A8/A9 binding to MDSC using an anti-carboxylated glycan Ab reduces MDSC levels in blood and secondary lymphoid organs in mice with metastatic disease. Therefore, the S100 family of inflammatory mediators serves as an autocrine feedback loop that sustains accumulation of MDSC. Since S100A8/A9 activation of MDSC is through the NF-kappaB signaling pathway, drugs that target this pathway may reduce MDSC levels and be useful therapeutic agents in conjunction with active immunotherapy in cancer patients.

Hepatosplenic T cell lymphoma. A review on 45 cases since the first report describing the disease as a distinct lymphoma entity in 1990

Peripheral T cell lymphomas are a heterogeneous group of post-thymic, mature lymphoid malignancies, accounting for approximately 10-15% of all non-Hodgkin's lymphomas. A rare entity within this group is represented by hepatosplenic gammadelta T cell lymphoma, which is characterized by primary extranodal disease with typical sinusoidal or sinusal infiltration of the liver and the spleen, respectively, by expression of the T cell receptor gammadelta chain, and by a number of other frequent clinicopathological features including aggressive course of disease. In contrast to these common attributes some biologic characteristics such as expression of cytotoxic proteins and cytotoxic activity have been controversial. In this review, clinicopathological, immunophenotypical, molecular biological, cytogenetical and biological findings, and diagnostic and therapeutic difficulties in hepatosplenic gammadelta T cell lymphoma are discussed.

Leukocyte common antigen--a diagnostic discriminant between hematopoietic and nonhematopoietic neoplasms in paraffin sections using monoclonal antibodies: correlation with immunologic studies and ultrastructural localization

Immunohistochemical localization of human leukocyte common antigen (LCA), a major membrane glycoprotein restricted to leukocytes, was evaluated in paraffin sections of a wide variety of hematopoietic and nonhematopoietic tissues (294 specimens) with monoclonal antibodies (PD7/26 and 2B11). In nonneoplastic tissues, LCA was identified on B and T lymphocytes, with variable immunoreactivities for plasma cells and histiocytes. By light microscopy and ultrastructurally, LCA was localized predominantly to the cell membrane and was also present focally in the cytoplasm. Myeloid cells at all stages of maturation were non-reactive, as were erythroid cells, megakaryocytes, and all non-hematopoietic tissues. Monocytes and mast cells, however, revealed membrane staining for LCA. In nearly all non-Hodgkin's lymphomas of the B- and T-cell types (74 of 80; 93 per cent), the lymphoid infiltrate was immunoreactive for LCA. In specimens from patients with Hodgkin's disease (nodular sclerosis and mixed cellularity type), rare Reed-Sternberg cells stained for LCA. Neoplastic cells were consistently immunoreactive for LCA in specimens from patients with chronic lymphocytic leukemia of the B- or T-cell type, prolymphocyte leukemia, and hairy cell leukemia. However, tissues from only three of eight cases of acute lymphoblastic leukemia were LCA-positive, with most non-reactive specimens exhibiting CALLA (J5) positivity. In cases of multiple myeloma, only minor populations of plasmacytic cells exhibited membrane staining for LCA. Nonhematopoietic neoplasms (102 evaluated), including small cell anaplastic carcinomas, amelanotic melanomas, alveolar rhabdomyosarcomas, Ewing's sarcoma, and germ cell tumors, were uniformly non-reactive. Human LCA represents an excellent cell marker for paraffin sections, to distinguish hematopoietic neoplasms, particularly of the lymphoid type, from poorly differentiated tumors of epithelial, mesenchymal, or neural derivation.

Analysis of the IgV(H) somatic mutations in splenic marginal zone lymphoma defines a group of unmutated cases with frequent 7q deletion and adverse clinical course

This study aimed to correlate the frequency of somatic mutations in the IgV(H) gene and the use of specific segments in the V(H) repertoire with the clinical and characteristic features of a series of 35 cases of splenic marginal zone lymphoma (SMZL). The cases were studied by seminested polymerase chain reaction by using primers from the FR1 and J(H) region. The results showed unexpected molecular heterogeneity in this entity, with 49% unmutated cases (less than 2% somatic mutations). The 7q31 deletions and a shorter overall survival were more frequent in this group. Additionally a high percentage (18 of 40 sequences) of SMZL cases showed usage of the V(H)1-2 segment, thereby emphasizing the singularity of this neoplasia, suggesting that this tumor derives from a highly selected B-cell population and encouraging the search for specific antigens that are pathogenically relevant in the genesis or progression of this tumor.

Consistent presence of isochromosome 7q in hepatosplenic T gamma/delta lymphoma: a new cytogenetic-clinicopathologic entity

Peripheral T-cell lymphoma (PTL), which is characterized by hepatosplenic presentation and the gamma/delta T-cell receptor (TCR) phenotype on the malignant cells, is a rare but distinct subtype of non-Hodgkin's lymphomas. Little is known about the chromosomal changes in these lymphomas. We report the cytogenetic analysis of three patients who had neoplastic proliferation of T gamma/delta cells in the spleen, bone marrow, and liver, but not in lymph nodes or skin. Isochromosome 7q and trisomy 8 were observed in all three patients. Isochromosome 7q as the sole abnormality has been previously reported in one patient with similar clinicopathologic features. It is suggested that i(7q) is a primary, nonrandom chromosomal abnormality in hepatosplenic T gamma/delta PTL.

Hepatosplenic and subcutaneous panniculitis-like gamma/delta T cell lymphomas are derived from different Vdelta subsets of gamma/delta T lymphocytes

Gamma/delta T cell lymphomas (gamma/delta TCL) represent rare, often aggressive types of T cell malignancy that are clinically and pathologically diverse. Most gamma/delta TCL occur as a hepatosplenic or subcutaneous type. To date, analysis of the T cell receptor delta (TCRS) gene repertoire of hepatosplenic gamma/delta TCL (gamma/delta HSTCL) and subcutaneous panniculitis-like gamma/delta TCL (gamma/delta SPTCL) has been reported only in a limited number of cases. In this study we analyzed 11 gamma/delta HSTCL and 4 gamma/delta SPTCL by polymerase chain reaction and immunostaining to determine their usage of the Vdelta subtypes (Vdelta1-6). It is noteworthy that 10 of 11 gamma/delta HSTCL expressed the Vdelta1 gene. The remaining case also expressed T cell receptor delta (TCRS) as determined by flow cytometry and TCRdelta rearrangement in Southern blot. However, the Vdelta gene expressed by this lymphoma could not be determined, which suggests usage of an as yet unidentified Vdelta gene. In striking contrast to the gamma/delta HSTCL, all 4 gamma/delta SPTCL expressed the Vdelta2 gene. Our data demonstrate that gamma/delta HSTCL are preferentially derived from the Vdelta1 subset of gamma/delta T lymphocytes, whereas gamma/delta SPTCL are preferentially derived from the Vdelta2 subset. The pattern of Vdelta gene expression in HSTCL and SPTCL corresponds to the respective, predominant gamma/delta T cell subsets normally found in the spleen and skin. This finding suggests that gamma/delta TCL are derived from normal gamma/delta T lymphocytes which reside in the affected tissues. Furthermore, the selective, lymphoma type-specific Vdelta gene segment usage may provide a molecular tool to distinguish better among various types of gamma/delta TCL lymphoma particularly in the clinically advanced, widely disseminated cases.

Splenic inflammatory myofibroblastic tumor (inflammatory pseudotumor): a clinicopathologic and immunophenotypic study of 12 cases

CONTEXT

Inflammatory pseudotumor is an uncommon and enigmatic lesion. The spindle cells found in this tumor have features of myofibroblasts. Because of the indefinite relationship of these lesions with inflammatory fibrosarcoma and their indefinite biologic behavior, inflammatory pseudotumor is currently classified as inflammatory myofibroblastic tumor (IMT). To date, only case reports or small series have been published on these tumors, which are primary in the spleen.

DESIGN

In this study, we describe the clinical, morphologic, and immunophenotypic findings of 12 cases of splenic IMT and examine their relationship to Epstein-Barr virus (EBV).

RESULTS

The patients included 8 women and 3 men, ranging from 19 to 77 years of age (mean, 53 years; median, 60 years). Demographic data were unavailable for 1 patient. Patients generally presented with abdominal pain (n = 5) and fever (n = 4). Associated lesions included renal cell carcinoma (n = 2), colonic adenocarcinoma (n = 1), and cholecystitis (n = 1). All tumors were composed of a bland spindle cell proliferation in association with a variable mixed inflammatory component. There were 2 growth patterns, namely, a cellular spindle cell pattern and a hypocellular fibrous pattern. An immunohistochemical panel confirmed the myofibroblastic nature of the spindle cells. The spindle cells of 2 cases were immunoreactive for EBV latent membrane protein 1, whereas 6 of 10 cases were positive for EBV-encoded RNA using in situ hybridization. Follow-up was available for 8 patients; 6 were alive with no evidence of recurrence and 2 were dead of other causes.

CONCLUSION

Splenic IMTs are uncommon lesions that can be distinguished from other conditions using a combination of clinical, histologic, and immunophenotypic findings. Epstein-Barr virus may play a role in the pathogenesis of splenic IMT, and there may be an association of splenic IMT with concomitant disease or malignancy. Most splenic IMTs have an excellent long-term prognosis.

Hepatosplenic and other gammadelta T-cell lymphomas

The 2005 Society for Hematopathology/European Association for Haematopathology Workshop session 11 was dedicated to hepatosplenic T-cell lymphoma (HSTCL). HSTCL is a rare aggressive type of extranodal lymphoma characterized by hepatosplenomegaly, bone marrow involvement, and peripheral blood cytopenias. HSTCL exhibits a distinctive pattern of infiltration; tumor cells preferentially infiltrate the sinusoids of the splenic red pulp, liver, and bone marrow. The tumor cells have a nonactivated cytotoxic T-cell immunophenotype and frequently carry a recurrent cytogenetic abnormality, isochromosome 7q. Most cases express the gammadelta T-cell receptor, but cases can have an alphabeta phenotype and are considered to be a variant of the disease. Although HSTCL is the prototype peripheral T-cell lymphoma expressing the gammadelta T-cell receptor, non-HSTCL proliferations of gammadelta T cells can involve other extranodal sites, mainly skin and mucosa. These gammadelta T-cell lymphomas display marked heterogeneity in clinical and histologic features. In contrast with HSTCL, non-HSTCL gammadelta T-cell lymphomas frequently have an activated cytotoxic phenotype and most likely are not a single disease entity.

Hepatosplenic gamma delta T-cell lymphoma. A distinctive aggressive lymphoma type

The T-cell receptor (TCR) expressed on the surface of most T-lymphocytes is of alpha beta type, and only a minority bear the gamma delta-TCR. Similarly, postthymic T-cell lymphomas rarely express gamma delta-TCR. Hepatosplenic gamma delta T-cell lymphoma is an uncommon entity that has so far not been widely recognized. We report one such case that has been comprehensively studied by multiple modalities and showed the unique occurrence of leukemic picture at presentation. The 39-year-old man presented with fever, marked weight loss, and massive splenomegaly. Peripheral blood showed thrombocytopenia and a white cell count of 5.8 x 10(9)/l, with 66% medium-sized lymphoid cells that had a round or folded nucleus, condensed chromatin and a moderate amount of pale blue cytoplasm. Splenectomy was performed and histologic examination of the spleen, bone marrow, liver, and abdominal lymph nodes demonstrated lymphoma infiltration with a predominantly sinusoidal pattern. Immunohistochemical studies of the lymphoma cells showed a T-cell phenotype: CD2+ CD3+ CD5+ CD7+ gamma delta-TCR+ alpha beta-TCR- CD56+ CD4- CD8- CD16- CD57-. Cytogenetic studies showed complex clonal chromosomal abnormalities of 44,X, -Y, -11, -22, + mar in 3/16 cells. Rearrangement of the TCR gamma chain gene was demonstrated by polymerase chain reaction; the TCR beta chain gene was partially chain reaction; the TCR beta chain gene was partially rearranged. The patient did not respond to single agent chemotherapy, but achieved clinical remission with combination chemotherapy. Based on the available data in the literature, hepatosplenic gamma delta T-cell lymphoma exhibits distinctive clinicopathologic features, and probably represents the neoplastic counterpart of splenic gamma delta T-lymphocytes. This disease is associated with a poor prognosis and usually relapses despite initial response to chemotherapy.

Hepatosplenic gamma/delta T-cell lymphoma in bone marrow. A sinusoidal neoplasm with blastic cytologic features

We report 8 cases of hepatosplenic T-cell lymphoma (HSTCL) involving bone marrow and correlate histologic findings with disease progression. Immunophenotypic analysis demonstrated mature, aberrant gamma/delta T-cell immunophenotypes. Isochromosome 7q was identified in 4 cases; 1 case showed the t(7;14)(q34;q13). Seven of 7 cases tested had monoclonal TCR gamma gene rearrangements. The initial diagnostic bone marrow biopsy specimens were hypercellular with a frequently subtle, predominantly sinusoidal infiltrate of atypical small to medium-sized lymphoid cells. In all cases, aspirate smears at diagnosis and in subsequent specimens contained malignant cells that resembled blasts, some with fine cytoplasmic granules. With progression, the pattern of HSTCL in bone marrow biopsy specimens became increasingly interstitial, and the neoplastic cells became larger. In aspirate smears, the proportion of blasts increased. Seven patients died; 1 was lost to follow-up. Autopsy performed on 1 patient demonstrated malignant cells within vascular channels in all organs sampled, with relatively little tumor formation, resembling intravascular lymphoma at these sites. HSTCL often can be recognized in bone marrow by its unique combination of a sinusoidal pattern in core biopsy specimens and blastic cytology in aspirate smears.

Hepatosplenic gamma/delta T-cell lymphoma: a report of two cases in immunocompromised patients, associated with isochromosome 7q

Two cases of peripheral T-cell lymphoma, characterized by hepatosplenic presentation and gamma/delta T-cell receptor phenotype on malignant cells, are reported. Little is known about the chromosomal changes in these peculiar lymphomas. We report the cytogenetic analysis of these two patients. Isochromosome 7q and trisomy 8 were observed. These abnormalities were reported previously in five cases of gamma/delta T-cell lymphoma. These two patients had lymphomatous infiltration of the spleen, liver, bone marrow, and (in one case) lymph nodes. These abnormalities occurred in immunocompromised patients (i.e., immunosuppressive therapy for kidney transplantation and chemotherapy for Hodgkin's disease), without Epstein-Barr virus infection stigmata in tumor cells.

Splenic marginal zone lymphoma. A distinct B-cell neoplasm

The splenic marginal zone is a morphologically and perhaps immunologically distinct B-cell compartment. Lymphomas arising from cells of the splenic marginal zone are rare. Here we describe the morphologic, immunologic, and clinical features of 14 cases. Patient age ranged from 35 to 79 years (median, 68 years) with a male-to-female ratio of 1:1.8. The spleen was uniformly enlarged (median, 1,540 g; range, 388-3,845 g) in all patients, the neoplastic infiltrate had a nodular pattern in three cases, nodular and diffuse in seven cases, and diffuse in four cases. The neoplastic cells had small to medium-sized nuclei with round, oval, or slightly indented contours, small eosinophilic nucleoli, and a moderate amount of pale cytoplasm. Extrasplenic involvement was present in 12 patients. Lymph nodes often had a vaguely nodular pattern and preservation of sinuses; bone marrow was infiltrated focally (seven cases) or diffusely (one case). Five patients had hepatic involvement. Ultrastructurally, neoplastic cells differed from other small B cells and resembled normal marginal zone cells by having long, serpentine rough endoplasmic reticulum profiles. All lymphomas marked as B cells and light chain restriction was demonstrated in 12 cases. Bcl-2 protein expression was present in all cases. Most cases (70%) were negative for DBA.44 (CD72). Plasmacytic differentiation was present in three cases. In conclusion, splenic marginal zone lymphoma is a B-cell neoplasm with distinctive clinical, morphologic, immunologic, and ultrastructural characteristics.

Splenic marginal zone lymphoma with or without plasmacytic differentiation

We report a series of 31 cases of splenic marginal zone lymphomas with an enlarged spleen and a multimicronodular macroscopic pattern. Two groups, A and B, were distinguished based on the presence (A) or absence (B) of a lymphoplasmacytic component with monoclonal immunoglobulin expression in the cytoplasm. There were no differences between the groups as far as age, sex, spleen weight, and progression. The only difference was the presence in group A of a monoclonal serum component and autoimmune disorders, particularly autoimmune hemolytic anemia. In most cases in which a liver and/or bone marrow biopsy was performed, lymphomatous infiltration was detected. Seven cases had a seric monoclonal IgM of 5 g/L or more and liver or bone marrow infiltration, corresponding to the definition of Waldenstrom's macroglobulinemia. Lymphoma cells had a monocytoid, centrocytoid and, in group A, lymphoplasmacytic morphology. The lymphomatous cells were positive for CD20, CD45 RA, and bcl-2. They expressed IgD in 9 cases, partially in 6, and were negative for IgD in 9 of the 24 cases studied. Progression seems to be slow, with a long survival. Three patients presented with transformation into a large B-cell lymphoma, which was responsible for death in two patients.

Higher levels of surface CD20 expression on circulating lymphocytes compared with bone marrow and lymph nodes in B-cell chronic lymphocytic leukemia

Differential expression of CD20 surface antigen in B-cell neoplasms at different sites is largely unknown. The number of CD20 antibodies bound per cell (CD20 ABC) in bone marrow (BM), peripheral blood (PB), and lymph node aspirate (LNA) samples from patients with B-cell chronic lymphocytic leukemia (B-CLL) or other B-cell disease was studied using quantitative flow cytometry. CD20 ABC differed significantly with the specimen type in B-CLL, being highest in PB (mean, 9,051) and lower in BM (mean, 4,067) and LNA (mean, 3,951). No difference in CD20 ABC between BM and PB samples was found in splenic lymphoma, mantle cell lymphoma, or follicular lymphoma. Also, we found a significant difference of CD20 ABC by type of disease: lowest in B-CLL; higher in splenic, follicular, and mantle cell lymphoma; and highest in hairy cell leukemia. The lower CD20 surface antigen levels in BM and LNA than in PB in B-CLL may have clinical relevance with regard to the efficacy of rituximab therapy.

Hepatosplenic gamma/delta T-cell lymphoma in immunocompromised patients. Report of two cases and review of literature

We describe 2 male patients in whom hepatosplenic gamma/delta T-cell lymphoma (HSTL) developed 6 and 10 years after renal transplantation. The onset was abrupt with systemic symptoms, cytopenia, and hepatosplenomegaly. The histologic examination of the spleen (case 1), liver, and bone marrow revealed sinusoidal infiltrates of markedly abnormal lymphocytes. The neoplastic cells in these cases were CD2+, CD3+, CD4-, CD5-, CD7+, CD8+, CD16+, CD56+, beta F1-negative, and TIA-1-negative. Both cases displayed clonal rearrangement of the T-cell receptor (TCR) delta gene and the TCR beta gene. The spleen in case 1 was positive for Epstein-Barr virus genome and showed TCR-gamma gene rearrangement by polymerase chain reaction. Isochromosome 7 [i(7)(q10)] was found in each case. Both patients died within 4 months of diagnosis. HSTL has been reported in only 5 renal transplant recipients. HSTL may be relatively more frequent in immunocompromised patients compared with the general population.

Somatic mutation analysis of IgH variable regions reveals that tumor cells of most parafollicular (monocytoid) B-cell lymphoma, splenic marginal zone B-cell lymphoma, and some hairy cell leukemia are composed of memory B lymphocytes

The cell of origin of parafollicular (monocytoid) B cell lymphoma (PBCL), splenic marginal zone lymphoma (SMZL), and hairy cell leukemia (HCL) is controversial. To better understand the relationship between these low-grade B-cell neoplasms, we analyzed the nucleotide sequences of the rearranged immunoglobulin heavy (IgH) chain variable (V) region of the clonal population of cells in five cases of PBCL, four cases of SMZL, and seven cases of HCL to determine whether these neoplasms could be differentiated by the degree of somatic mutation in the IgH V gene or by the IgH V gene family usage. DNA was extracted from diagnostic material and clonality confirmed by PCR. The DNA was reamplified using V heavy chain family specific primers, and the amplicons were sequenced. Sequences were compared with germline IgH V gene sequences, and base changes were determined to be silent or to represent amino acid replacements by using three different methods. Four of five (80%) cases of PBCL, three of four (75%) cases of SMZL, and three of seven (43%) cases of HCL showed evidence of antigen selection, suggesting that these neoplasms involved clonal expansions of postgerminal center memory lymphocytes. Only SMZL showed a preferential usage of V(H)1 family genes.

Splenic hamartoma and capillary hemangioma are distinct entities: immunohistochemical analysis of CD8 expression by endothelial cells

The histologic and immunohistologic features of two morphologically similar splenic tumors, a capillary hemangioma and a splenic hamartoma, are reported. The hemangioma was composed predominantly of small vascular channels lined by endothelium expressing factor VIII-related antigen and lacking T-subset antigen (CD8). In contrast, the splenic hamartoma was predominantly a spindle cell lesion with numerous vascular channels coursing through the tumor; these contained splenic-type endothelium expressing both CD8 and factor VIII-related antigen. Our results justify the concept that the splenic hamartoma is a tumor of splenic origin or a true hamartoma and is distinct from the splenic capillary hemangioma.

gammadelta T-cell lymphomas: a homogeneous entity?

gammadelta T-cells comprise an immunologically distinct lymphoid population, characterized by specific morphological, phenotypical and functional properties. Therefore it seems reasonable to speculate that neoplasms derived from this particular T-cell subset display distinct features. Indeed, the prototype gammadelta T-cell lymphoma, hepatosplenic T-cell lymphoma constitutes a unique clinicopathological entitity which is intimately associated with a gammadelta T-cell phenotype. However, gammadelta T-cell lymphomas have also been described in other extranodal sites where, unlike reactive gammadelta T-cells and hepatosplenic gammadelta T-cell lymphomas, they display an important morphological heterogeneity. Moreover, these nonhepatosplenic gammadelta T-cell lymphomas are essentially not that different from their alphabeta T-cell receptor for antigen (TCR)-expressing counterparts and thus may be incorporated in the established T-cell lymphoma subclasses. However, subtle differences regarding their histopathological appearance as well as their biological behaviour indicate that further studies to determine the exact significance of TCR expression are required. Such inquiries may contribute to the general understanding of T-cell lymphomagenesis in general, which is still obscure.

Hepatosplenic gamma-delta T-cell lymphoma as a late-onset posttransplant lymphoproliferative disorder in renal transplant recipients

We report 2 cases of renal transplant recipients in whom hepatosplenic gamma-delta T-cell lymphoma (gamma-delta HSTCL) developed 5 and 10 years after transplantation. Both patients had marked hepatosplenomegaly, B symptoms (weight loss, fever, and night sweats), and abnormal peripheral blood findings, including anemia in both, thrombocytopenia and leukoerythroblastic changes in 1, and leukocytosis in the other. Markedly atypical lymphoid infiltrate of intermediate to large cells was observed in the spleen, liver, and bone marrow. The malignant cells showed typical immunophenotype of gamma-delta T cells (CD2+, CD3+, CD4-, CD8-, CD7+, gamma-delta T-cell receptor-positive, and alpha-beta T-cell receptor-negative) with clonal T-cell receptor gene rearrangement and were of the V-delta-1 subset. In addition, the cells contained a cytolytic granule-associated protein, TIA-1, and Fas ligand, indicating cytotoxic T-cell differentiation. The malignant T cells in both cases were of host tissue origin. Both cases were negative for Epstein-Barr virus genome using Southern blot analysis. The patients did not respond to reduction of immunosuppression. Despite initial response to chemotherapy, both patients died within 6 months of diagnosis. Our findings indicate that gamma-delta HSTCL can occur as a late complication in transplant recipients.

Prognostic Factors of Hepatosplenic T-cell Lymphoma: Clinicopathologic Study of 28 Cases

Hepatosplenic T-cell lymphoma (HSTCL) is a rare type of lymphoma. Patients have a poor prognosis, and there is no standard of care. We evaluated 28 HSTCL patients to determine factors that may be associated with outcome. There were 19 men and 9 women with a median age of 32.5 years. Most patients had massive splenomegaly, and bone marrow showed sinusoidal involvement by lymphoma. The HSTCL cells expressed γδ T-cell receptor (TCR) in 20 (74%), αβ TCR in 5 (19%), and neither in 2 (7%) patients (1 case not assessed). Conventional cytogenetics and/or fluorescence in situ hybridization analysis in 24 patients at diagnosis showed isochromosome 7q (i7q) in 10 (42%) and trisomy 8 in 8 (33%) patients. Median overall survival (OS) and event-free survival (EFS) were each 28.3 months. Serum bilirubin level ≥1.5 mg/dL, αβ TCR expression, and trisomy 8 each correlated significantly with shorter OS and EFS. Patients with HSTCL received a variety of chemotherapy regimens with no regimen better than any other. However, patients who underwent stem cell transplant showed longer survival (OS: hazard ratio 0.3, P=0.09; EFS: hazard ratio 0.2, P=0.034). In conclusion, although HSTCL patients have a poor prognosis overall, the data presented support the novel suggestions that HSTCL patients can be stratified into 2 prognostic groups, with an elevated serum bilirubin level, αβ TCR expression, and trisomy 8 identifying a poorer prognostic group. In addition, the outcomes of this patient cohort suggest that stem cell transplantation has value for the treatment of patients with HSTCL.

Natural resistance of lethally irradiated F1 hybrid mice to parental marrow grafts is a function of H-2/Hh-restricted effectors

The natural resistance of F1 hybrid mice against parental bone marrow grafts is thought to be mediated by natural killer (NK)-like effector cells. However, unlike the NK cell activity against a wide range of tumors and normal cells, hybrid resistance is characterized by the immunogenetic specificity controlled by a set of unique noncodominant genes denoted as Hh. Two alternative hypotheses can account for the specificity. Thus, the specificity may reflect either the Hh restriction of effectors or the Hh gene control of mechanisms regulating non-Hh-restricted effector activity. In this study, therefore, we tested the recognition specificity of putative effectors mediating hybrid resistance in lethally irradiated H-2b/d and H-2b/k F1 hybrid mice to the engraftment of parental H-2b bone marrow. As a direct means of defining the effector specificity, rejection of parental bone marrow grafts was subjected to competitive inhibition in situ by irradiated tumor cells. Of the 16 independent lines of lymphoma and other hemopoietic tumor cells tested, the ability to inhibit hybrid resistance was the exclusive property of all tumors derived from mice homozygous for the H-2Db region, regardless of whether the tumor cells were susceptible or resistant to NK cell-mediated cytotoxicity in vitro. Four cell lines heterozygous for the H-2Db were noninhibitory, including one that is susceptible to natural killing. Pretreatment of the F1 hosts with an interferon inducer augmented the resistance with no alteration in the recognition specificity of effector cells. Therefore, natural resistance to parental H-2b bone marrow grafts was mediated by effectors restricted by the H-2Db/Hh-1b gene(s), and not by the nonrestricted NK cells detectable in conventional in vitro assays.