The Organization of the Pig T-Cell Receptor γ (TRG) Locus Provides Insights into the Evolutionary Patterns of the TRG Genes across Cetartiodactyla.

The domestic pig (Sus scrofa) is a species representative of the Suina, one of the four suborders within Cetartiodactyla. In this paper, we reported our analysis of the pig TRG locus in comparison with the loci of species representative of the Ruminantia, Tylopoda, and Cetacea suborders. The pig TRG genomic structure reiterates the peculiarity of the organization of Cetartiodactyla loci in TRGC "cassettes", each containing the basic V-J-J-C unit. Eighteen genes arranged in four TRGC cassettes, form the pig TRG locus. All the functional TRG genes were expressed, and the TRGV genes preferentially rearrange with the TRGJ genes within their own cassette, which correlates the diversity of the γ-chain repertoire with the number of cassettes. Among them, the TRGC5, located at the 5' end of the locus, is the only cassette that retains a marked homology with the corresponding TRGC cassettes of all the analyzed species. The preservation of the TRGC5 cassette for such a long evolutionary time presumes a highly specialized function of its genes, which could be essential for the survival of species. Therefore, the maintenance of this cassette in pigs confirms that it is the most evolutionarily ancient within Cetartiodactyla, and it has undergone a process of duplication to give rise to the other TRGC cassettes in the different artiodactyl species in a lineage-specific manner.

Next-generation sequencing confirms T-cell clonality in a subset of pediatric pityriasis lichenoides.

BACKGROUND: Pityriasis lichenoides (PL) is a papulosquamous disease that affects both adults and children. Previous studies have shown a subset of this entity to have clonal T-cell populations via PCR-based assays. In this study, we sought to implement next-generation sequencing (NGS) as a more sensitive and specific test to examine for T-cell clonality within the pediatric population. METHODS: We identified 18 biopsy specimens from 12 pediatric patients with clinical and histopathologic findings compatible with PL. Patient demographics, clinical features, management, and histopathologic findings were reviewed. All specimens were analyzed for clonality with NGS of T-cell receptor beta (TRB) and gamma (TRG) genes. RESULTS: Of the 12 patients, 9 (75%) had complete resolution of lesions at the time of data collection (mean follow-up 31 months). The remaining three patients significantly improved with methotrexate (with or without acitretin). Interestingly, 7 of 12 patients (58%) and 9 of 17 biopsy specimens (53%) showed evidence of T-cell clonality. Two patients showed matching TRB clones from different anatomic sites. CONCLUSIONS: T-cell clonality is a common finding in PL, probably representing a "reactive clonality" rather than a true lymphoproliferative disorder. Clonality alone cannot be used as a means to distinguish PL from lymphomatoid papulosis or cutaneous lymphoma.

Clonal cutaneous and neurosyphilis: A pitfall in pseudolymphoma diagnosis.

Syphilis is a sexually transmitted infectious disease caused by the bacterium Treponema pallidum and can cause a wide variety of cutaneous manifestations, most commonly, a papulosquamous eruption of the trunk and extremities. Treatment with penicillin is curative. We report a case of a 69-year-old man who presented with recent onset of blurry vision and a nonpainful, nonpruritic eruption of pink-to-violaceous dermal nodules on his upper trunk and upper extremities. Biopsies of two separate locations revealed a dense superficial and deep perivascular atypical lymphocytic infiltrate with admixed plasma cells, histiocytes, and eosinophils. Some scattered cells expressed CD30, PD1, BCL-6, and ICOS. T-cell receptor (TCR)-rearrangement showed an identical TCR-gamma clone between both biopsy specimens. The patient was subsequently seen by ophthalmology and diagnosed with acute anterior uveitis. Rapid plasma reagin was reactive and cerebrospinal fluid studies showed findings consistent with a diagnosis of neurosyphilis. A T. pallidum immunostain of the skin biopsies was performed upon re-review, and was diffusely positive for spirochetes at the dermal-epidermal junction and within injured vessels. The patient was treated with penicillin G with near-resolution of his skin lesions. This case highlights the unusual ability of syphilis to mimic a T-cell lymphoma with matching clones across two different biopsy sites.

A Comprehensive Annotation of the Channel Catfish (Ictalurus punctatus) T Cell Receptor Alpha/Delta, Beta, and Gamma Loci.

The complete germline repertoires of the channel catfish, Ictalurus punctatus, T cell receptor (TR) loci, TRAD, TRB, and TRG were obtained by analyzing genomic data from PacBio sequencing. The catfish TRB locus spans 214 kb, and contains 112 TRBV genes, a single TRBD gene, 31 TRBJ genes and two TRBC genes. In contrast, the TRAD locus is very large, at 1,285 kb. It consists of four TRDD genes, one TRDJ gene followed by the exons for TRDC, 125 TRAJ genes and the exons encoding the TRAC. Downstream of the TRAC, are 140 TRADV genes, and all of them are in the opposite transcriptional orientation. The catfish TRGC locus spans 151 kb and consists of four diverse V-J-C cassettes. Altogether, this locus contains 15 TRGV genes and 10 TRGJ genes. To place our data into context, we also analyzed the zebrafish TR germline gene repertoires. Overall, our findings demonstrated that catfish possesses a more restricted repertoire compared to the zebrafish. For example, the 140 TRADV genes in catfish form eight subgroups based on members sharing 75% nucleotide identity. However, the 149 TRAD genes in zebrafish form 53 subgroups. This difference in subgroup numbers between catfish and zebrafish is best explained by expansions of catfish TRADV subgroups, which likely occurred through multiple, relatively recent gene duplications. Similarly, 112 catfish TRBV genes form 30 subgroups, while the 51 zebrafish TRBV genes are placed into 36 subgroups. Notably, several catfish and zebrafish TRB subgroups share ancestor nodes. In addition, the complete catfish TR gene annotation was used to compile a TR gene segment database, which was applied in clonotype analysis of an available gynogenetic channel catfish transcriptome. Combined, the TR annotation and clonotype analysis suggested that the expressed TRA, TRB, and TRD repertoires were generated by different mechanisms. The diversity of the TRB repertoire depends on the number of TRBV subgroups and TRBJ genes, while TRA diversity relies on the many different TRAJ genes, which appear to be only minimally trimmed. In contrast, TRD diversity relies on nucleotide additions and the utilization of up to four TRDD segments.

Memory and naïve gamma delta regulatory T-cell gene expression in the first 24-weeks of peanut oral immunotherapy.

BACKGROUND: Peanut oral immunotherapy (POIT) has provided desensitization to peanut allergic individuals. Limited immunological evaluation exists during the first 24-weeks of POIT. OBJECTIVE: Regulatory T-cells (Tregs) are antigen induced immunosuppressive T-cells important in establishing tolerance. Delineation of early immunologic changes contributing to the development of peanut desensitization would help clarify the mechanism of action in POIT. We performed single-cell RNA sequencing (scRNAseq) on Tregs in pediatric subjects undergoing POIT during the first 24-weeks of therapy to evaluate early immunological changes induced by POIT. METHODS: PBMC samples from peanut allergic subjects between 5 and 12 years of age enrolled in a Phase 1/2a POIT study were collected and analyzed at 0, 6, and 24-weeks after POIT initiation and samples were compared to healthy non-peanut allergic controls. Tregs were enriched from PBMCs and scRNAseq analysis performed. Cell Ranger 3.1.0 (10× Genomics) was utilized to identify cell clusters and differentially expressed genes, and results were analyzed with Seurat suite version 3.0.0. RESULTS: Gene analysis revealed 10 major clusters corresponding to different cell types observed to change during POIT when compared to the healthy, non-peanut-allergic state. scRNAseq analysis of Tregs revealed strong CD3G expression correlating with gdTregs. scRNAseq analysis of gdTregs revealed dynamic changes occurring within the first 6-weeks of treatment and cell frequencies of naïve and memory gdTregs at 24-weeks of treatment reducing to levels similar to healthy controls. Analysis of transcriptomic cell identity analysis using SingleR showed gene expression in gdTregs similar to healthy control after 24-weeks of POIT treatment. scRNAseq analysis revealed alterations in gene expression for memory and naïve gdTregs during this timeframe. Specifically, expression of OX40R (TNFRSF4), GITR (TNFRSF18), TGFB1, CTLA4, ISG20, CD69 were upregulated in memory gdTregs compared to naive gdTregs by 24-weeks of POIT, while IL7R and SELL were downregulated in memory gdTregs compared to naïve gdTregs. CONCLUSIONS: There are specific expression profiles of peripheral naïve and mature gdTreg cells in peanut allergic patients undergoing POIT in the first 24-weeks of treatment implicating pathways involved in maintenance of immune homeostasis. gdTreg cells may contribute to the tolerogenic effect of POIT within the first 24-weeks of POIT treatment. These findings suggest that gdTregs cells may be an early marker of desensitization in subjects undergoing POIT.

Childhood Adiposity Associated With Expanded Effector Memory CD8+ and Vδ2+Vγ9+ T Cells.

CONTEXT: Adult obesity is associated with chronic low-grade inflammation and may give rise to future chronic disease. However, it is unclear whether adiposity-related inflammation is already apparent in childhood. OBJECTIVE: To study associations between child adiposity measures with circulating monocytes and naive and memory subsets in CD4, CD8, and γδ T cell lineages. METHODS: Ten-year-old children (n = 890) from the Generation R Cohort underwent dual-energy x-ray absorptiometry and magnetic resonance imaging for body composition (body mass index [BMI], fat mass index [FMI], android-to-gynoid fat mass ratio, visceral fat index, liver fat fraction). Blood samples were taken for detailed immunophenotyping of leukocytes by 11-color flow cytometry. RESULTS: Several statistically significant associations were observed. A 1-SD increase in total FMI was associated with +8.4% (95% CI 2.0, 15.2) Vδ2+Vγ9+ and +7.4% (95% CI 2.4, 12.5) CD8+TEMRO cell numbers. A 1-SD increase in visceral fat index was associated with +10.7% (95% CI 3.3, 18.7) Vδ2+Vγ9+ and +8.3% (95% CI 2.6, 14.4) CD8+TEMRO cell numbers. Higher android-to-gynoid fat mass ratio was only associated with higher Vδ2+Vγ9+ T cells. Liver fat was associated with higher CD8+TEMRO cells but not with Vδ2+Vγ9+ T cells. Only liver fat was associated with lower Th17 cell numbers: a 1-SD increase was associated with -8.9% (95% CI -13.7, -3.7) Th17 cells. No associations for total CD8+, CD4+ T cells, or monocytes were observed. BMI was not associated with immune cells. CONCLUSION: Higher Vδ2+Vγ9+ and CD8+TEMRO cell numbers in children with higher visceral fat index could reflect presence of adiposity-related inflammation in children with adiposity of a general population.

Validation of a Next-Generation Sequencing-Based T-Cell Receptor Gamma Gene Rearrangement Diagnostic Assay: Transitioning from Capillary Electrophoresis to Next-Generation Sequencing.

Assessment of T-cell receptor γ gene (TRG) rearrangements is an importants consideration in the diagnostic workup of lymphoproliferative diseases. Although fragment analysis by PCR and capillary electrophoresis (CE) is the current standard of such assessment in clinical molecular diagnostic laboratories, it does not provide sequence information and is only semi-quantitative. Next-generation sequencing (NGS)-based assays are an attractive alternative to the conventional fragment size-based methods, given that they generate results with specific clonotype sequence information and allow for more accurate quantitation. The present study evaluated various test parameters and performance characteristics of a commercially available NGS-based TRG gene-rearrangement assay by testing 101 clinical samples previously characterized by fragment analysis. The NGS TRG assay showed an overall accuracy of 83% and an analytical specificity of 100%. The concordance rates were 88% to 95% in the Vγ1-8, Vγ10, and Vγ11 gene families, but lower in the Vγ9 gene family. This difference was mostly attributed to the incomplete polyclonal symmetry resulting from the two-tube CE assay versus the one-tube design of the NGS assay. The NGS assay also demonstrated strengths in distinguishing clonotypes of the same fragment size. This clinical validation demonstrated robust performance of the NGS-based TRG assay and identified potential pitfalls associated with CE assay design that are important for understanding the observed discrepancies with the CE-based assay.

Lactobacillus acidipiscis Induced Regulatory Gamma Delta T Cells and Attenuated Experimental Autoimmune Encephalomyelitis.

Multiple sclerosis is a chronic autoimmune disease involving the central nervous system, and shows a high disability rate. Its pathogenesis is complicated, and there is no good treatment. In recent years, with in-depth studies on the regulation of gastrointestinal flora, the relationship between the mammalian immune system and the intestinal flora has been extensively explored. Changes in the composition and structure of the gastrointestinal flora can affect the characteristics and development of the host immune system and even induce a series of central nervous system inflammation events. The occurrence and development of multiple sclerosis are closely related to the continuous destruction of the intestinal barrier caused by intestinal dysbacteriosis. In this study, we analyzed Lactobacillus acidipiscis in a mouse model of experimental autoimmune encephalomyelitis (EAE). We found that the amount of L. acidipiscis in the intestinal tract was inversely proportional to the progress of EAE development. In addition, the number of CD4+ FOXP3+ regulatory T cells in the mesenteric lymph nodes of mice increased significantly after the mice were fed with L. acidipiscis, and the differentiation of CD4+ T cells to Th1 and Th17 cells was inhibited. However, the protective effect of L. acidipiscis was lost in γδ T cell-deficient mice and hence was concluded to depend on the presence of regulatory γδ T cells in the intestinal epithelium. Moreover, including L. acidipiscis enhanced the development of Vγ1+γδ T cells but suppressed that of Vγ4+γδ T cells. In summary, our results demonstrated the ability of L. acidipiscis to induce generation of regulatory γδ T cells that suppress the development of the encephalomyelitic Th1 and Th17 cells and the progress of EAE.

Characterization of the domestic goat γδ T cell receptor gene loci and gene usage.

Goats and cattle diverged 30 million years ago but retain similarities in immune system genes. Here, the caprine T cell receptor (TCR) gene loci and transcription of its genes were examined and compared to cattle. We annotated the TCR loci using an improved genome assembly (ARS1) of a highly homozygous San Clemente goat. This assembly has already proven useful for describing other immune system genes including antibody and leucocyte receptors. Both the TCRγ (TRG) and TCRδ (TRD) loci were similarly organized in goats as in cattle and the gene sequences were highly conserved. However, the number of genes varied slightly as a result of duplications and differences occurred in mutations resulting in pseudogenes. WC1+ γδ T cells in cattle have been shown to use TCRγ genes from only one of the six available cassettes. The structure of that Cγ gene product is unique and may be necessary to interact with WC1 for signal transduction following antigen ligation. Using RT-PCR and PacBio sequencing, we observed the same restriction for goat WC1+ γδ T cells. In contrast, caprine WC1+ and WC1- γδ T cell populations had a diverse TCRδ gene usage although the propensity for particular gene usage differed between the two cell populations. Noncanonical recombination signal sequences (RSS) largely correlated with restricted expression of TCRγ and δ genes. Finally, caprine γδ T cells were found to incorporate multiple TRD diversity gene sequences in a single transcript, an unusual feature among mammals but also previously observed in cattle.

Nodal EBV-positive polymorphic B cell lymphoproliferative disorder with plasma cell differentiation: clinicopathological analysis of five cases.

Plasma cell differentiation (PCD) is frequently observed in some entities of non-Hodgkin B cell lymphoma, including both low-grade and high-grade lymphomas. However, except for plasmablastic lymphoma and primary effusion lymphoma, EBV+ B cell lymphoproliferative disorder (LPD) with PCD has not been well addressed due to its rarity. We clinicopathologically examined five cases of nodal EBV+ polymorphic B cell LPD with PCD (PBLPD-PCD) initially diagnosed as polymorphic EBV+ diffuse large B cell lymphoma, not otherwise specified (DLBCL-NOS) with PCD (n = 3) and methotrexate-associated B cell LPD (MTX-associated B-LPD) (n = 2). One case had a concomitant brain lesion which was clinically diagnosed as EBV-related encephalitis. This patient received therapy with vidarabine, and both the brain lesion and the nodal EBV+ PBLPD-PCD lesions disappeared. Another case was characterized by Mott cell differentiation. This case was the first reported case of EBV+ B cell lymphoma or LPD with Mott cell differentiation. The two cases of MTX-associated B cell LPD which arose in patients with rheumatoid arthritis spontaneously regressed after MTX cessation. TCRγ and IGH PCR analysis was performed in four cases. Two cases had TCRγ rearrangements, but no IGH rearrangements. The other two cases had no rearrangements in these genes. We concluded that nodal EBV+ PBLPD-PCD is rare, with heterogeneous characteristics. PCR analysis revealed that nodal EBV+ PBLPD-PCD may have only TCR clonality and no IGH clonality. Considering the partial or complete loss of CD20 expression on the tumor cells, this result may be confusing for accurate diagnosis of EBV+ PBLPD-PCD, and pathologists need to be aware of this phenomenon to avoid misdiagnosis.

Immune and TRG repertoire signature of the thymus in Down syndrome patients.

BACKGROUND: Patients with Down syndrome (DS) are at increased risk for infections and autoimmune disorders. Although several immunological abnormalities were previously found, differences in T cell receptor repertoire have never been shown. Thus we compared the T cell receptor gamma (TRG) repertoire in DS and non-syndromic pediatric patients by next-generation sequencing, in addition to other immunological markers. METHODS: Genomic DNA was extracted from thymuses of pediatric patients who underwent heart surgery, where six were with DS and six were non-syndromic patients. Peripheral blood counts, T cell subpopulations, thymus TCR excision circles (TRECs), spectratyping, and next-generation sequencing for TRG were analyzed. RESULTS: The mean age of the patients was 7 months and the mean lymphocyte count was slightly lower in patients with DS, whereas thymus TREC results were similar to non-syndromic patients (p = 0.197). The TRG repertoire analysis showed that patients with DS had a significantly larger number of unique TRG sequences, together with decreased clonal expansion. Lastly, the V and J gene usages in the thymus were similar in DS and non-syndromic patients. CONCLUSIONS: Patients with DS showed increased TRG repertoire diversity with decreased clonal expansion compared to non-syndromic patients. IMPACT: Alterations in T cell receptor gamma repertoire were found in patients with Down syndrome using next-generation sequencing (NGS) technique. Patients showed increased repertoire diversity and decreased clonal expansion compared to controls. These findings add to previous reports on abnormalities of other immune system components in patients with Down syndrome. NGS technique may point out differences not seen by previous methods. Repertoire abnormalities may contribute to those patients' predisposition to infections and autoimmune diseases.

The expansion of the TRB and TRG genes in domestic goats (Capra hircus) is characteristic of the ruminant species.

BACKGROUND: Goats (Capra hircus), one of the first domesticated species, are economically important for milk and meat production, and their broad geographical distribution reflects their successful adaptation to diverse environmental conditions. Despite the relevance of this species, the genetic research on the goat traits is limited compared to other domestic species. Thanks to the latest goat reference genomic sequence (ARS1), which is considered to be one of the most continuous assemblies in livestock, we deduced the genomic structure of the T cell receptor beta (TRB) and gamma (TRG) loci in this ruminant species. RESULTS: Our analyses revealed that although the organization of the goat TRB locus is broadly similar to that of the other artiodactyl species, with three in-tandem D-J-C clusters located at the 3' end, a complex and extensive series of duplications have occurred in the V genes at the 5' end, leading to a marked expansion in the number of the TRBV genes. This phenomenon appears to be a feature of the ruminant lineage since similar gene expansions have also occurred in sheep and cattle. Likewise, the general organization of the goat TRG genes is typical of ruminant species studied so far, with two paralogous TRG loci, TRG1 and TRG2, located in two distinct and distant positions on the same chromosome as result of a split in the ancestral locus. Each TRG locus consists of reiterated V-J-J-C cassettes, with the goat TRG2 containing an additional cassette relative to the corresponding sheep and cattle loci. CONCLUSIONS: Taken together, these findings demonstrate that strong evolutionary pressures in the ruminant lineage have selected for the development of enlarged sets of TRB and TRG genes that contribute to a diverse T cell receptor repertoire. However, differences observed among the goat, sheep and cattle TRB and TRG genes indicate that distinct evolutionary histories, with independent expansions and/or contractions, have also affected each ruminant species.

Primary central nervous system ALK-positive anaplastic large cell lymphoma with CD56 abnormally expression in a Chinese child: Challenge in diagnostic practice.

Anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALK + ALCL) is most frequent in youth and possesses a broad morphologic spectrum. However, involvement in central nervous system (CNS) is definitely rare. The case we presented was a 12-year-old Chinese male who presented with headache and emesis for a couple of days. The neoplastic component was smaller cells resembling starry-sky growth pattern and immunohistochemical stained positively for CD30, ALK1, and CD56. Monoclonal T-cell receptor (TCRγ) gene rearrangement and gene translocation involving ALK identified by fluorescence in situ hybridization (FISH) using ALK break apart probe supported the diagnosis of ALK + ALCL. This case showed ALK + ALCL occur in a rare site with an abnormal CD56 expression. Awareness of this entity is important to distinguish it from other intracranial lymphoma.

Dissection of the Human T-Cell Receptor γ Gene Repertoire in the Brain and Peripheral Blood Identifies Age- and Alzheimer's Disease-Associated Clonotype Profiles.

The immune system contributes to neurodegenerative pathologies. However, the roles of γδ T cells in Alzheimer's disease (AD) are poorly understood. Here, we evaluated somatic variability of T-cell receptor γ genes (TRGs) in patients with AD. We performed deep sequencing of the CDR3 region of TRGs in patients with AD and control patients without dementia. TRG clones were clearly detectable in peripheral blood (PB) and non-neuronal cell populations in human brains. TRG repertoire diversity was reduced during aging. Compared with the PB, the brain showed reduced TRGV9 clonotypes but was enriched in TRGV2/4/8 clonotypes. AD-associated TRG profiles were found in both the PB and brain. Moreover, some groups of clonotypes were more specific for the brain or blood in patients with AD compared to those in controls. Our pilot deep analysis of T-cell receptor diversities in AD revealed putative brain and AD-associated immunogenic markers.

Primary cutaneous γδ T-cell lymphoma with unusual immunophenotype: A case report and review of published work.

Primary cutaneous γδ T-cell lymphoma (CGD-TCL) is a rare form of primary cutaneous lymphoma. The histopathological features of CGD-TCL are still unclear because of its rarity. Here, we report a case of a 77-year-old Japanese man who presented with a 9-month history of erythematous plaques on his left forearm. Skin biopsy specimens revealed the infiltration of atypical medium/large-sized lymphocytes from the epidermis to the deep dermis. Atypical lymphocytes were positive for CD3, CD5, CD8 and Vδ1, and negative for CD4, CD7, CD56, EBER-ISH, intracellular antigen-1, granzyme B and perforin. CD30 was partially expressed. We also reviewed 246 cases of CGD-TCL from the published work. CD4- CD8- double-negative cases were 113 of 196 cases (57.6%), followed by CD4- CD8+ cases (52/196, 26.5%). CD5 was expressed in 25.8% of the cases (34/132). At least one cytotoxic molecule marker was expressed in 150 of 160 cases (93.8%). Some cases showed an indolent clinical course, especially in mycosis fungoides-like CGD-TCL cases. CD5 positivity and lack of cytotoxic molecule expression could be associated with a better prognosis. In addition, CD30 expression was found in approximately half of CGD-TCL cases (51/112 cases), suggesting that brentuximab vedotin could be a good treatment option for such patients. Further studies with more cases with detailed clinical and pathological information are necessary to elucidate the etiology and prognostic markers of this entity.

Recognition of Listeria Infection by Germline Elements of the Vγ1.1 Vδ6.3 TCR.

γδNKT cells are an abundant γδT cell population with restricted Vγ1.1 Vδ6.3 gene usage and phenotypic and functional similarity to conventional αß-invariant NKT cells. The γδNKT population responds to Listeria infections, but specific ligands are not known. In this work, we studied the CDR3 requirements of the γδNKT TCR, Vγ1.1Vδ6.3 for recognizing naive macrophages, and macrophages infected with Listeria We expressed four different variants of the Vγ1.1Vδ6.3 TCR in TCR-deficient hybridomas, one with germline-encoded sequences and three with nongermline-encoded sequences. All of the hybridomas were activated when cultured in the presence of macrophages, and the activation was increased when the macrophages were infected with Listeria This indicates that these TCRs can recognize a self-ligand present in macrophages and suggests that the ligand is modified or upregulated when the cells are infected with Listeria One of the three nongermline-encoded Vγ1.1 variants induced a lower activation level compared with the other variants tested in this study, suggesting that recognition of the Listeria-induced ligand involves the CDR3γ region of the TCR.

Anaplastic Large T-Cell Lymphoma in the Intestine of Dogs.

Anaplastic large T-cell lymphoma (ALTCL) is a rare subtype of non-Hodgkin T-cell lymphoma that occasionally occurs in the gastrointestinal tract of humans. Enteropathy-associated T-cell lymphoma (EATL) type 1 is the most common type of intestinal lymphoma in dogs, and ALTCL has not previously been reported in the intestinal tract of dogs. Thirteen dogs with intestinal masses diagnosed as intestinal lymphoma with anaplastic morphology were reviewed. Clinical data, including treatment protocols, were available for 11 cases. Immunohistochemistry for CD3, CD20, and CD30 was performed for all cases in addition to PCR for Antigen Receptor Rearrangements (PARR) for assessment of clonality. Eight (62%) of the cases presented with intestinal perforation, and all cases had 1 or more masses arising from the small intestine. Histologically, all cases were characterized by transmural infiltrates of large, CD3-positive and frequently CD30-positive cells. Neoplastic T cells had marked anisocytosis and anisokaryosis, prominent nucleoli, and occasionally indented to reniform nuclei. There was abundant necrosis and inflammation with occasional vascular invasion within neoplastic masses. All cases had a monoclonal T-cell receptor γ gene rearrangement. The median survival time was 5 days, with 1 dog surviving 2 years after the initial diagnosis. ALTCL can occur as an aggressive transmural lymphoma in the gastrointestinal tract of dogs and commonly causes intestinal perforation. ALTCL can be differentiated from EATL type 1 and might have implications for accurate prognostication and selection of therapeutic options in the future.

Expression of TCR genes in adult and larval Xenopus laevis.

In order to better understand the development and function of γδ T cells in Xenopus frogs, it is necessary to determine where and when γδ T cells are found in Xenopus tissues. This study examined the expression of TCR genes, focused primarily on TCR γ, in tissues of adult and larval Xenopus laevis and provide new data about the expression pattern of these different TCR genes in this anuran amphibian. TCR gene expression was detected by RT-PCR in adult frog tissues including the thymus, spleen, skin, intestine, lung, and liver, but not the testes. TCR γ and ß genes were detected in the larval (tadpole) tail and intestine. The absence of RAG-1 expression in these larval tissues is consistent with differentiation of the T cells in the thymus. Together, these data provide evidence that migration of these cells from the thymus likely occurs relatively early in larval development. These studies provide a necessary foundation for future studies of the functions of γδ T cells in amphibians, which are placed at an intermediate position flanked by fishes on one end and mammals and chickens on the other.

Comparative Study of the Clinical Pathology, Immunophenotype, Epstein-Barr Virus Infection Status, and Gene Rearrangements in Adult and Child Patients With Hydroa Vacciniforme-Like Lymphoproliferative Disorder.

BACKGROUND: Hydroa vacciniforme-like lymphoproliferative disorder (HVLPD) is a rare Epstein-Barr virus (EBV)-associated lymphoma that mainly affects children. OBJECTIVES: To examine the similarities and differences in the clinical pathological features, EBV infection status, and gene rearrangements in adults and children patients with HVLPD. METHODS: We compared the clinical manifestations, histopathology, immunophenotypical features, EBV infection status, and T-cell receptor gene rearrangements in the adult and children HVLPD groups. RESULTS: Clinical manifestations differed between children and adults groups. The children were characterized by blisters and severe facial swelling, whereas the adults were characterized by mild facial swelling and papules. Mosquito bite was significantly related to morbidity in the children group. Histologically, the number of mast cells in the adult group was greater than in the children group (P < 0.05). There were no significant differences in EBV infection status or TCR-γ gene rearrangements between 2 groups. CONCLUSIONS: There were differences in clinical pathology and prognosis between the 2 groups. A higher mast cell count and T-cell phenotype might be associated with a poor prognosis.

Diagnostic Utility of Isolated Tube C Positivity in T-Cell Receptor ß Testing Using BIOMED-2 Primers.

OBJECTIVES: T-cell receptor (TCR) gene rearrangement studies are widely used for assessing T-cell clonality. The frequency and significance of clonal peaks restricted to TCR ß (TCRB) tube C are uncertain. We retrospectively reviewed 80 TCR studies performed on bone marrow/peripheral blood. METHODS: TCRB and TCR γ (TCRG) analyses were performed using BIOMED-2 primers. A peak was considered clonal or atypical if it was reproducible and 5× or more or 3× to 5× polyclonal background, respectively. RESULTS: TCRB analysis demonstrated 12 (15%) of 80 cases with one to four isolated peaks in tube C (>3×) with polyclonal pattern in tubes A and B. TCRG analysis was monoclonal in two cases (both definite T-cell neoplasms), polyclonal in four, and oligoclonal in six. Of the 10 cases without clone in TCRG, six had autoimmune disorder and none had T-cell neoplasm. CONCLUSIONS: Peaks restricted to TCRB tube C in the TCR analysis may be misleading, as it is often not indicative of an overt T-cell neoplasm.