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A combination of cellular and humoral immunological assaults directed against follicular matrical cells is suspected to cause alopecia areata (AA) in humans. The specific aims of this study were to determine whether cytotoxic T lymphocytes (CTL) were increased in the blood and skin lesions of canine AA. Additionally, we wished to determine if circulating antifollicular antibodies were present in the dog. Finally, we aimed to investigate whether bulbar inflammation was associated with decreased matrical cell proliferation and keratinocyte apoptosis. Canine AA lesions were infiltrated by intrabulbar CTL, perifollicular helper T cells and dendritic cells. A higher percentage of CTL was present in canine AA peripheral blood compared with that of normal dogs. Tissue-fixed and circulating antifollicular IgG antibodies were detected. Reduced matrical proliferation and increased keratinocyte apoptosis was observed in inflamed hair bulbs. This study demonstrates the existence of antifollicular cell-mediated and humoral immunological responses in canine AA. Resume— L'association d'agressions immunologiques cellulaires et humorales dirigees contre les cellules matricielles folliculaires est suspectee d'etre a l'origine de l'Alopecie Areata chez l'homme. Le but de cette etude etait de montrer si le nombre de lymphocytes T cytotoxiques est augmente dans le sang et dans les lesions cutanees lors d'Alopecie Areata chez le chien. En plus, nous souhaitions montrer la presence d'anticorps circulants antifolliculaire chez le chien. Enfin, nous voulions voir si l'inflammation du bulbe pileux etait associee a une diminution de la proliferation des cellules matricielles et une apoptose des keratinocytes. Lors d'Alopecie Areata chez le chien, existe une infiltration lesionnelle par des lymphocytes T cytotoxiques intrabulbaires, des lymphocytes T auxiliaires perifolliculaires et des cellules dentritiques. Le pourcentage de lymphocytes T cytotoxiques etait plus important dans le sang peripherique provenant de sujets a Alopecie Areata que dans le sang d'animaux sains. Par ailleurs, des anticorps antifolliculaire (IgG) circulants et fixes dans les tissus sont detectes. Une reduction de la proliferation des cellules matricielles et une augmentation de l'apoptose des keratinocytes sont observees dans les bulbes pileux atteints. Cette etude demontre l'existence de reponses immunologiques cellulaires et humorales contre le follicule pileux dans l'Alopecie Areata du chien. [Olivry, T., Moore, P.F., Naydan, D.K., Puget, B.J., Affolter, V.K., Kline, A.E. Antifollicular cell-mediated and humoral immunity in canine alopecia areata (Immunite contre le follicule pileux dans l'Alopecie Areata du chien). Veterinary Dermatology 1996; 7: 67–79.] Resumen Se cree que la alopecia areata (AA) en la especie humana resulta de la combinacion de la accion inmunologica celular y humoral contra celulas de la matriz folicular. Los objetivos especificos de este estudio fueron determinar si los linfocitos T citotoxicos (CTL) se encontraban aumentados en sangre y en las lesiones cutaneas de animales con AA. Ademas, descamos investigar la posible presencia de anticuerpos antifoliculares circulantes en el perro. Finalmente, nos propusimos investigar si la inflamacion bulbar se encontraba asociada a una disminucion en la proliferacion de celulas de la matriz y a la apoptosis de queratinocitos. Las lesiones de la AA canina mostraban infiltracion por CTL intrabulbares, celulas T colaboradoras y celulas dendriticas. Se encontro un porcentaje mayor de CTL en la sangre periferica de perros con AA respecto a perros normales. Se detectaron anticuerpos IgG antifoliculares circulantes y en tejido fijado. Se observo una disminucion en la proliferacion matrical y un aumento en queratinocitos apoptoticos en los bulbos foliculares inflamados. Este estudio demuestra la existencia de respuestas inmunitarias antifoliculares de tipo celular y humoral en la AA canina. [Olivry, T., Moore, P.F., Naydan, D.K., Puget, B.J., Affolter, V.K., Kline, A.E. Antifollicular cell-mediated and humoral immunity in canine alopecia areata (Immunidad antifolicular en la alopecia areata canina). Veterinary Dermatology 1996; 7: 67–79.] Zusammenfassung— Eine Kombinaton von zellularen und humoralen immunologischen Angriffen, die gegen die follikularen Matrixzellen gerichtet sind, wird als Ursache bei der Alopecia areata (AA) des Menschen vermutet. Die besondere Absicht dieser Studie war, festzustellen, ob die zytotoxischen T-Lymphozyten (CTL) im Blut und in den Hautveranderungen bei kaniner AA erhoht sind. Zusatzlich wollten wir feststellen, ob beim Hund zirkulierende antifollikulare Antikorper vorkommen. Schlieslich beabsichtigten wir, zu untersuchen, ob die bulbare Entzundung mit verminderter Matrixzellproliferation und Keratinozytenapoptose einhergeht. Die Veranderungen bei kaniner AA wurden von intrabulbaren CTL, perifollikularen T-Helferzellen und dendritischen Zellen infiltriert. Verglichen mit dem peripheren Blut gesunder Hunde kam bei kaniner AA eine hoherer Prozentsatz an CTL vor. Es wurden gewebsfixierte und zirkulierende antifollikulare IgG-Antikorper festgestellt. In entzundeten Haarbulbi wurde eine reduzierte Matrixproliferation und eine erhohte Keratinozytenapoptose beobachtet. Diese Studie zeigt die Existenz von antifollikularen zellvermittelten und humoralen immunologischen Reaktionen bei kaniner AA. [Olivry, T., Moore, P. F., Naydan, D. K., Puget, B. J., Affolter, V. K., Kline, A. E. Antifollicular immunity in canine alopecia areata (Antifollikulare Immunitat bei der Alopecia areata des Hundes). Veterinary Dermatology 1996; 7: 67–79.]

In human medicine, narrow-band ultraviolet B (NB-UVB) phototherapy has been used to treat various T-cell-mediated skin diseases. However, the effect of NB-UVB on inflamed canine skin remains uncertain.To investigate the effect of NB-UVB phototherapy on the skin of dogs with hapten-induced contact dermatitis.Seven healthy beagles without skin problems.Dogs were irradiated with varying doses of NB-UVB to determine the minimal erythema dose (MED). After determining the MEDs of six dogs (excluding one of the seven whose skin did not show a visible reaction), we investigated the effect of NB-UVB on their inflamed skin by topically applying 2,4-dinitrochlorobenzene (DNCB), which causes type 1 helper T cell (Th1)- and cytotoxic T-cell (Tc)1-induced skin inflammation. We then irradiated the skin with NB-UVB. We analysed the treated skin samples via histopathological and immunohistochemical methods, and TdT-mediated dUTP nick-end labelling (TUNEL) to demonstrate apoptotic cells. We also analysed the cytokine gene transcription via real-time quantitative reverse transcription PCR.The NB-UVB MEDs caused mild inflammatory changes yet no severe epidermal exfoliations in the irradiated skin. In DNCB-treated skin irradiated by the NB-UVB MEDs, TUNEL-positive dermal apoptotic cells were increased significantly compared with those of DNCB-treated, nonirradiated skin. INF-γ and TNF-α transcription levels in DNCB-treated, irradiated skin were significantly lower than those in the DNCB-treated, nonirradiated skin.Phototherapy using NB-UVB MEDs attenuated cutaneous Th1 and Tc1 cytokine responses with minimal skin damage in a canine model of hapten-induced contact dermatitis.En médecine humaine, la photothérapie ultraviolette B (NB-UVB) à bande étroite a été utilisée pour traiter diverses maladies de la peau à médiation par les lymphocytes T. Cependant, l'effet de NB-UVB sur la peau canine enflammée reste incertain.Étudier l'effet de la photothérapie NB-UVB sur la peau de chiens atteints de dermatite de contact induite par l'haptène.Sept beagles en bonne santé sans problèmes de peau. MÉTHODES ET MATÉRIEL: Les chiens ont été irradiés avec des doses variables de NB-UVB pour déterminer la dose minimale d'érythème (DEM). Après avoir déterminé les MED de six chiens (à l'exclusion de l'un des sept dont la peau n'a pas montré de réaction visible), nous avons étudié l'effet du NB-UVB sur leur peau enflammée en appliquant localement du 2,4-dinitrochlorobenzène (DNCB), qui provoque un inflammation de type 1 de la peau induite par les lymphocytes T auxiliaires (Th1) et les lymphocytes T cytotoxiques (Tc)1. Nous avons ensuite irradié la peau avec du NB-UVB. Nous avons analysé les échantillons de peau traités via des méthodes histopathologiques et immunohistochimiques, et le marquage dUTP nick-end (TUNEL) médié par TdT pour démontrer les cellules apoptotiques. Nous avons également analysé la transcription du gène des cytokines par PCR de transcription inverse quantitative en temps réel. RÉSULTATS: Les MED NB-UVB ont provoqué de légers changements inflammatoires, mais aucune exfoliation épidermique grave de la peau irradiée. Dans la peau traitée au DNCB irradiée par les MED NB-UVB, les cellules apoptotiques dermiques positives pour TUNEL ont augmenté de manière significative par rapport à celles de la peau non irradiée traitée au DNCB. Les niveaux de transcription d'INF-γ et de TNF-α dans la peau irradiée traitée au DNCB étaient significativement inférieurs à ceux de la peau non irradiée traitée au DNCB.La photothérapie utilisant des MED NB-UVB a atténué les réponses des cytokines cutanées Th1 et Tc1 avec des lésions cutanées minimales dans un modèle canin de dermatite de contact induite par l'haptène.INTRODUCCIÓN: en medicina humana, la fototerapia ultravioleta B de banda estrecha (NB-UVB) se ha utilizado para tratar diversas enfermedades de la piel mediadas por células T. Sin embargo, el efecto de NB-UVB sobre la piel canina inflamada sigue siendo incierto. OBJETIVOS: investigar el efecto de la fototerapia NB-UVB en la piel de perros con dermatitis de contacto inducida por hapteno. ANIMALES: Siete perros Beagle sanos sin problemas en la piel. MÉTODOS Y MATERIALES: los perros se irradiaron con dosis variables de NB-UVB para determinar la dosis mínima de eritema (MED). Después de determinar las MEDs de seis perros (excluyendo uno de los siete cuya piel no mostró una reacción visible), investigamos el efecto de NB-UVB en su piel inflamada aplicando tópicamente 2,4-dinitroclorobenceno (DNCB), que causa inflamación de la piel por tipo 1 linfocito T colaborador (Th1) y linfocito T citotóxico (Tc) 1. Luego irradiamos la piel con NB-UVB. Analizamos las muestras de piel tratadas a través de métodos histopatológicos e inmunohistoquímicos, y marcaje de extremos rotos (Nick-end labelling) dUTP mediado por TdT (TUNEL) para demostrar células apoptóticas. También analizamos la transcripción de genes de citoquinas mediante PCR cuantitativa de transcripción inversa en tiempo real. RESULTADOS: las NB-UVB MEDs causaron cambios inflamatorios leves pero no exfoliaciones epidérmicas graves en la piel irradiada. En la piel tratada con DNCB irradiada por las MEDs de NB-UVB, las células apoptóticas dérmicas positivas a TUNEL aumentaron significativamente en comparación con las de la piel no irradiada tratada con DNCB. Los niveles de transcripción de INF-γ y TNF-α en la piel irradiada tratada con DNCB fueron significativamente más bajos que los de la piel no irradiada tratada con DNCB. CONCLUSIÓN Y RELEVANCIA CLÍNICA: la fototerapia con NB-UVB MEDs atenuó las respuestas de las citoquinas cutáneas Th1 y Tc1 con un daño cutáneo mínimo en un modelo canino de dermatitis de contacto inducida por hapteno.In der Humanmedizin wird die Schmalband Ultraviolet B (NB-UVB) Phototherapie verwendet, um verschiedene T-Zell-mediierte Hauterkrankungen zu behandeln. Die Auswirkung von NB-UVB auf entzündete Hundehaut bleibt jedoch noch unklar.Eine Untersuchung der Auswirkung von NB-UVB Phototherapie auf die Haut von Hunden mit Hapten-induzierter Kontaktdermatitis.Sieben gesunde Beagles ohne Hautprobleme.Die Hunde wurden mit unterschiedlichen Dosen an NB-UVB bestrahlt, um die minimale Erythem Dosis (MED) zu bestimmen. Nach Bestimmung der MEDs bei sechs Hunden (einer der sieben Hunde wurde ausgenommen, da seine Haut keine sichtbare Reaktion zeigte), untersuchten wir die Auswirkung von NB-UVB auf ihre entzündete Haut durch topische Verabreichung von 2,3-Dinitrochlorobenzen (DNCB), welches eine Typ 1 Helfer T Zell (Th1)- und zytotoxische T-Zell (Tc)1-induzierte Hautentzündung verursacht. Danach wurde die Haut mit NB-UVB bestrahlt. Wir analysierten die behandelten Hautproben mittels histopathologischer und immunhistochemischer Methoden und TdT-mediierter dUTP Nick-Ende Färbung (TUNEL), um apoptotische Zellen zu demonstrieren. Wir analysierten auch die Zytokin Gentranskription mittels Real-Time Quantitativer Reverser Transkriptions PCR.Die NB-UVB MEDs verursachten in der bestrahlten Haut milde entzündliche Veränderungen, jedoch keine hochgradigen epidermalen Exfoliationen. Bei der DNCB-behandelten Haut, die mit NB-UVB MEDS bestrahlt worden war, nahm die Anzahl der TUNEL-positiven dermalen apoptotischen Zellen im Vergleich zu den mit DNCB-behandelter, nicht bestrahlter Haut signifikant zu. INF-γ und TNF-α Transkriptionswerte bei DNCB-behandelter, bestrahlter Haut waren signifikant niedriger als jene in der DNCB-behandelten, nicht bestrahlten Haut.Phototherapie mittels NB-UVB MEDS verminderte die kutane Th1 und Tc1 Zytokin Antwort bei minimalen Hautveränderungen in einem Hundemodell von Hapten-induzierter Kontaktdermatitis.背景: ヒトでは、ナローバンド紫外線B(NB-UVB) 光線療法は、様々なT細胞介在性皮膚疾患の治療に用いられている。しかし、炎症を起こした犬の皮膚に対するNB-UVBの効果はまだ不明である。 目的: 本研究の目的は、ハプテン誘発性接触皮膚炎のイヌの皮膚に対するNB-UVB光線療法の効果を調査することであった。 被検動物: 皮膚に問題のない健常ビーグル7頭。 材料と方法: 犬に様々な線量のNB-UVBを照射し、最小紅斑量 (MED) を決定した。6頭の犬 (皮膚が目に見える反応を示さなかった7頭のうち1頭を除く) のMEDを決定した後、1型ヘルパーT細胞 (Th1) および細胞障害性T細胞 (Tc)1誘発性皮膚炎症を引き起こす2,4-ジニトロクロロベンゼン (DNCB) を局所的に塗布することで、炎症を起こした皮膚に対するNB-UVBの効果を調査した。次に、この皮膚にNB-UVBを照射した。照射した皮膚サンプルは、病理組織学的および免疫組織化学的手法により解析し、TdT-mediated dUTP nick-end labelling (TUNEL)によりアポトーシス細胞を検出した。また、リアルタイム定量逆転写PCRでサイトカイン遺伝子の転写を解析した。 結果: NB-UVB MEDは、照射された皮膚に軽度の炎症性変化を引き起こしたが、重度の表皮剥離はなかった。NB-UVB MEDを照射したDNCB処理皮膚では, TUNEL陽性の真皮アポトーシス細胞がDNCB処理した非照射皮膚に比べて有意に増加した。DNCB処理した照射皮膚のINF-γおよびTNF-α転写レベルは、DNCB処理した非照射皮膚の転写レベルに比べて有意に低かった。 結論と臨床的妥当性: NB-UVB MEDを用いた光線療法は、ハプテン誘発性接触皮膚炎イヌモデルにおいて、皮膚の損傷を最小限に抑えながら、皮膚のTh1およびTc1サイトカイン反応を弱めた。.背景: 在人类医学中, 窄谱中波紫外线(NB-UVB)光疗已被用于治疗各种T细胞介导的皮肤病。然而, NB-UVB对犬发炎皮肤的影响仍不确定。 目的: 半抗原诱导出犬接触性皮炎,研究NB-UVB光疗对皮肤的影响。 动物: 7只健康比格犬, 无皮肤问题。 方法和材料: 用不同剂量的NB-UVB照射犬, 测定最小红斑剂量(MED)。在确定了6只犬的MED后 (不包括1只皮肤无可见反应的犬) , 我们研究NB-UVB对发炎皮肤的影响,通过局部涂抹2,4-二硝基氯苯(DNCB),引起1型辅助性T细胞(Th1)和细胞毒性T细胞(Tc)1诱导的皮肤炎症。然后我们用NB-UVB照射皮肤。我们通过组织病理学和免疫组织化学方法分析了治疗的皮肤样本, 并通过TdT介导的dUTP缺口末端标记(TUNEL)证明凋亡细胞。我们还通过实时定量逆转录PCR分析了细胞因子基因转录。 结果: NB-UVB MED在照射皮肤中引起轻度炎症变化, 但无重度表皮剥脱。DNCB处理、经NB-UVB MEDs照射皮肤, TUNEL阳性真皮凋亡细胞较DNCB处理、未照射皮肤显著增加。DNCB处理、照射皮肤的INF-γ和TNF-α转录水平显著低于DNCB处理、未照射皮肤。 结论和临床相关性: 在半抗原诱导的接触性皮炎犬模型中, 使用NB-UVB MED的光疗减弱了皮肤Th1和Tc1细胞因子反应, 减轻了皮肤损伤。.Na medicina humana, a fototerapia ultravioleta B de banda curta (NB-UVB) tem sido usada para tratar várias doenças cutâneas mediadas por células T. No entanto, o efeito de NB-UVB na pele canina inflamada permanece incerto.Investigar o efeito da fototerapia NB-UVB na pele de cães com dermatite de contato induzida por hapteno.Sete beagles saudáveis sem diagnóstico de dermatopatia. MÉTODOS E MATERIAIS: Os cães foram irradiados com doses variadas de NB-UVB para determinar a dose eritema mínima (MED). Depois de determinar as MEDs de seis cães (excluindo um dos sete cuja pele não mostrou uma reação visível), investigamos o efeito de NB-UVB em sua pele inflamada aplicando topicamente 2,4-dinitroclorobenzeno (DNCB), que causa inflamação cutânea mediada por células T-helper 1 (Th1) e por células T citotóxicas (Tc) 1. Em seguida, irradiamos a pele com NB-UVB. Analisamos as amostras de pele tratadas por meio de métodos histopatológicos e imuno-histoquímicos e marcação com dUTP nick-end (TUNEL) mediada por TdT para demonstrar células apoptóticas. Também analisamos a transcrição do gene da citocina via PCR de transcrição reversa quantitativa em tempo real.As MEDs de NB-UVB causaram leves alterações inflamatórias, mas não geraram esfoliação epidérmica grave na pele irradiada. Na pele tratada com DNCB irradiada pelas MEDs de NB-UVB, as células apoptóticas dérmicas positivas para TUNEL aumentaram significativamente em comparação com aquelas da pele não irradiada tratada com DNCB. Os níveis de transcrição de INF-γ e TNF-α em pele irradiada tratada com DNCB foram significativamente mais baixos do que na pele não irradiada tratada com DNCB. CONCLUSÃO E RELEVÂNCIA CLÍNICA: A fototerapia com MEDs de NB-UVB atenuou as respostas cutâneas de citocinas Th1 e Tc1 com injúria cutânea mínima em um modelo canino de dermatite de contato induzida por hapteno.

Canine epitheliotropic cutaneous T-cell lymphoma (CTCL) is a spontaneous neoplasm of the skin and mucous membranes of aged dogs. The WHO classification of tumours of haematopoietic and lymphoid tissues in human beings recognizes three forms of cutaneous epitheliotropic CTCL: mycosis fungoides (MF), Sezary syndrome and pagetoid reticulosis. In this series of dogs (n = 56), there were 39 cases of MF, 16 cases of pagetoid reticulosis and a single case of Sezary syndrome. Epitheliotropic T cells in CTCL lesions expressed CD8 in 44 of 55 dogs (80%) assessed; neither CD4 nor CD8 was expressed in the remainder. This contrasts with human MF in which alphabeta T-cell receptors (TCR) and CD4 are dominantly expressed. Molecular clonality assessment of canine epitheliotropic CTCL utilizing PCR primers specific for canine TCR gamma (TCRG) was performed. Of the 45 canine cases assessed, TCRG monoclonality was detected in 36 cases (80%). TCR typing of canine epitheliotropic CTCL revealed that TCRgammadelta was expressed in 60% of cases, including all cases of canine pagetoid reticulosis assessed. Either muco-cutaneous junctions or tissues of the oral cavity were the sites of lesions in 32 dogs (57%) with epitheliotropic CTCL. Analysis of the topography of lesions revealed an association with TCR type. If epitheliotropic CTCL lesions occurred in both locations, T cells were more likely to express TCRgammadelta (gammadelta : alphabeta = 2.0). These data establish that canine skin trafficking T cells have a far wider range than previously thought; this includes tongue, gingival, buccal and palatine mucosae.

Cutaneous lymphoproliferative diseases encompass a spectrum of lesions, ranging from self-limiting, reactive infiltrates to high-grade lymphomas. In humans, cutaneous lymphocytosis (CL) refers to self-limiting or slowly progressive monomorphic lymphocytic infiltrates of mostly unknown cause. It morphologically mimics cutaneous lymphoma. CL in cats also is a slowly progressive disease. Immunophenotyping and clonality testing of feline CL support an indolent lymphoma for the majority of cases studied. This study reports CL in dogs. Erythematous, scaly and alopecic macules, patches or plaques were present in eight dogs. Breed predilection was not observed; six of eight dogs were females; and ages ranged from 5 to 14 years. Diffuse monomorphic non-epitheliotropic infiltrates of CD3(+) (eight of eight), CD45(-) (four of eight) or CD45(+/-) (four of eight) and CD45RA(-) (seven of eight) T lymphocytes were present in the superficial and mid-dermis. Further immunophenotyping of five cases revealed TCR-gammadelta(+) T cells (one of five) or TCR-alphabeta(+) (four of five) T cells. TCR-alphabeta(+) populations were either CD8(+) (two of four) or CD4(-)CD8(-) (2/4). Clonality testing found clonal (seven of eight) or pseudoclonal (one of eight) rearrangement of the TCR-gamma locus of the lesional T cells. Prednisone, prednisolone and methylprednisolone acetate were the most commonly administered drugs. The lesions remained stable for long periods up to 6 years. Five dogs were euthanized due to progression of the skin lesions (three of five), peripheral lymphadenopathy of unknown origin (one of five) or high-grade lymphoma (one of five). One dog was lost for follow-up and two dogs are still alive (17 and 9 months after diagnosis). Canine CL is best considered an initially indolent lymphoma, with slow progression and a potential for progression to high-grade lymphoma.

Clinical, morphological and immunohistochemical features of cutaneous lymphocytosis, an uncommon disease histologically resembling well-differentiated malignant lymphoma, were characterized in 23 cats. Clinical outcome was correlated with histomorphology and immunophenotype in an attempt to predict benign vs. malignant behaviour. The disease mainly affected older cats. Lesions were solitary in 61% of cats and often characterized by alopecia (73.9%), as well as erythema, scaling and ulceration. The lateral thorax was most commonly affected (43.5%). Pruritus was frequent (65.2%). Systemic signs included anorexia and weight loss. Morphologically, lesions were characterized by dermal infiltrations of well-differentiated CD3+ T-cells (100%) and aggregates of CD79+ B-cells (64.3%). Cutaneous lymphocytosis is slowly progressive and relatively benign, although in some cats systemic signs led to euthanasia. Four of 12 euthanized cats and one live cat also had lymphoid infiltrates in internal organs. Unfortunately, we were unable to predict clinical outcome by histological and immunohistochemical evaluations of skin lesions.

In canine and human atopic patients, the intracutaneous injection of offending allergens is followed by the development of both immediate and late-phase reactions. The present study was performed to expand on the characterization and dynamics of inflammatory cell subsets during IgE-mediated late-phase reactions in canine skin. Three normal dogs and three Dermatophagoides farinae-allergic dogs were selected for this experiment. All dogs were challenged intradermally with mite allergen, purified anticanine IgE antibodies (positive control) or phosphate-buffered saline (negative control). Skin biopsies were obtained before and 6, 12 and 24 h post-injection. Sections were stained with metachromatic and eosinophil-specific histological stains. Additionally, we used an immunohistochemical method with antibodies specific for canine leukocyte antigens. This study confirmed the occurrence of a late-phase reaction in atopic skin following allergen challenge, and in normal and atopic canine skin after intradermal injection of IgE-specific antibodies. Whereas early emigrating dermal cells were composed chiefly of neutrophil and activated eosinophil granulocytes, there was an influx of alpha beta T-lymphocytes and dermal dendritic cells in later stages of the late-phase reactions. Because IgE-mediated late-phase reactions resemble spontaneous atopic canine skin lesions, both at macroscopic and microscopic levels, we propose the use of similar challenges to study the anti-inflammatory effects of anti-allergic drugs in a pre-clinical setting.

Pseudopelade is a primary scarring (cicatricial) alopecia of humans characterized by lymphocyte-rich inflammation centred around the hair follicle isthmus. Lymphocyte folliculotropism is associated with isthmus apoptosis and, ultimately, follicular destruction and dermal fibrosis. In a cat, an acquired alopecia was diagnosed as pseudopelade based on the following criteria: (i) an adult-onset, patchy to diffuse nonpruritic hair loss; (ii) an early folliculo-destructive phase in which lymphocytes and dendritic cells accumulated in and around the follicular isthmus; and (iii) a late stage in which the lower segments of hair follicles underwent atrophy and were replaced by fibrosing tracts. Additionally, immunological investigations characterized the cytotoxic phenotype of isthmotropic lymphocytes and demonstrated the presence of circulating IgG autoantibodies specific for multiple follicular antigens. Altogether, the results of the present study suggest an immune-mediated pathogenesis for this case of feline pseudopelade, similarly to that causing alopecia areata in humans and other mammalian species.

Three domestic rabbits (Oryctolagus cuniculus) with cutaneous lymphoma are described. Two rabbits were young (7 weeks and 1 years) and were euthanized within 1 week of showing clinical signs. Lymphoma was found in the skin and internal organs. The third rabbit was 9.5 years of age, and lived for more than 1 year after diagnosis. No response was seen to either 2 months of alpha-interferon administration or a 2.5-week course of isotretinoin treatment. After 1 year the rabbit died suddenly; the owner refused necropsy. Immunologic stains of the tumour in all three rabbits showed T cells to be the lymphoma cell type.

Seventeen cutaneous and oral tumours with light microscopic features of plasmacytomas from 16 dogs were studied. Clinically, most neoplasms were benign, although three recurred after excision and three were locally invasive. Tumours most often arose on the pinnae, digits, gingiva, and inguinal regions near areas of chronic inflammation and exhibited variable degrees of plasmacytic differentiation microscopically. Diagnosis of plasmacytoma was confirmed in paraffin-embedded tissues with a panel of leukocyte differentiation antigen markers that included cross-reactive antibodies for Mb-1 (CD79a), CD3, and vimentin and canine-specific antibodies for CD45RA and CD18. Immunoreactivity for Mb-1 and CD45RA, including staining of multinucleate cells and cells with karyomegaly, confirmed a B-cell origin of neoplasms, while staining for CD3 and CD18 revealed an extensive network of infiltrative T-cells and dendritic cells in tumours suggestive of a directed immune response. These findings (i) demonstrate the value of using a panel of antibodies for leukocyte antigens to differentiate plasmacytomas from other cutaneous and oral round cell tumours, and (ii) suggest that immune recognition and responsiveness within tumours may play a role in the behaviour of plasmacytomas in dogs by affecting tumour cell growth and differentiation.

Cutaneous T-cell lymphoma (CTCL) in dogs is a heterogeneous disease complex, which consists of nonepitheliotropic (NE) and epitheliotropic forms. These lymphomas are readily recognized by the presence of dominant populations of cytologically atypical lymphocytes.The objective of this study was to introduce the key features of inflamed NE-CTCL, which is easily confused with reactive, inflammatory histiocytic disease.Twenty-four dogs (mean age 7.5 years) presented with inflamed NE-CTCL. Lesions presented as nodules, plaques or masses. An initial diagnosis of cutaneous reactive histiocytosis (11 dogs) or histiocytic neoplasia (three dogs) was made by primary pathologists.Lesions were assessed by histology and immunohistochemistry to detect canine leukocyte antigens. Lesional genomic DNA was extracted and gene rearrangement analysis of the T-cell receptor γ locus was assessed.The cutaneous lesions consisted of pleocellular infiltration of the dermis with variable extension into the subcutis. The lesions often surrounded vessels and adnexae. Epitheliotropism was minimal or lacking. Small lymphocytes, plasma cells and intermediate to large, cytologically atypical lymphocytes were scattered between prominent histiocytic infiltrates. Atypical lymphocytes often had marked variation in the intensity of CD3 expression. Molecular clonality analysis of the T-cell receptor γ locus revealed clonal expansion of T cells in 22 of 23 dogs tested.The recognition of inflamed NE-CTCL and its differentiation from cutaneous reactive histiocytosis depends on careful assessment of lymphocyte morphology and immunostaining patterns. Confirmation of the diagnosis is best accomplished by T-cell antigen receptor gene rearrangement analysis.

Canine epitheliotropic cutaneous T-cell lymphoma (CTCL) is a spontaneous neoplasm of the skin and mucous membranes of aged dogs. The WHO classification of tumours of haematopoietic and lymphoid tissues in human beings recognizes three forms of cutaneous epitheliotropic CTCL: mycosis fungoides (MF), Sézary syndrome and pagetoid reticulosis. In this series of dogs (n = 56), there were 39 cases of MF, 16 cases of pagetoid reticulosis and a single case of Sézary syndrome. Epitheliotropic T cells in CTCL lesions expressed CD8 in 44 of 55 dogs (80%) assessed; neither CD4 nor CD8 was expressed in the remainder. This contrasts with human MF in which alphabeta T-cell receptors (TCR) and CD4 are dominantly expressed. Molecular clonality assessment of canine epitheliotropic CTCL utilizing PCR primers specific for canine TCR gamma (TCRG) was performed. Of the 45 canine cases assessed, TCRG monoclonality was detected in 36 cases (80%). TCR typing of canine epitheliotropic CTCL revealed that TCRgammadelta was expressed in 60% of cases, including all cases of canine pagetoid reticulosis assessed. Either muco-cutaneous junctions or tissues of the oral cavity were the sites of lesions in 32 dogs (57%) with epitheliotropic CTCL. Analysis of the topography of lesions revealed an association with TCR type. If epitheliotropic CTCL lesions occurred in both locations, T cells were more likely to express TCRgammadelta (gammadelta : alphabeta = 2.0). These data establish that canine skin trafficking T cells have a far wider range than previously thought; this includes tongue, gingival, buccal and palatine mucosae.

Cutaneous lymphoproliferative diseases encompass a spectrum of lesions, ranging from self-limiting, reactive infiltrates to high-grade lymphomas. In humans, cutaneous lymphocytosis (CL) refers to self-limiting or slowly progressive monomorphic lymphocytic infiltrates of mostly unknown cause. It morphologically mimics cutaneous lymphoma. CL in cats also is a slowly progressive disease. Immunophenotyping and clonality testing of feline CL support an indolent lymphoma for the majority of cases studied. This study reports CL in dogs. Erythematous, scaly and alopecic macules, patches or plaques were present in eight dogs. Breed predilection was not observed; six of eight dogs were females; and ages ranged from 5 to 14 years. Diffuse monomorphic non-epitheliotropic infiltrates of CD3(+) (eight of eight), CD45(-) (four of eight) or CD45(+/-) (four of eight) and CD45RA(-) (seven of eight) T lymphocytes were present in the superficial and mid-dermis. Further immunophenotyping of five cases revealed TCR-gammadelta(+) T cells (one of five) or TCR-alphabeta(+) (four of five) T cells. TCR-alphabeta(+) populations were either CD8(+) (two of four) or CD4(-)CD8(-) (2/4). Clonality testing found clonal (seven of eight) or pseudoclonal (one of eight) rearrangement of the TCR-gamma locus of the lesional T cells. Prednisone, prednisolone and methylprednisolone acetate were the most commonly administered drugs. The lesions remained stable for long periods up to 6 years. Five dogs were euthanized due to progression of the skin lesions (three of five), peripheral lymphadenopathy of unknown origin (one of five) or high-grade lymphoma (one of five). One dog was lost for follow-up and two dogs are still alive (17 and 9 months after diagnosis). Canine CL is best considered an initially indolent lymphoma, with slow progression and a potential for progression to high-grade lymphoma.

Background – Cutaneous T-cell lymphoma (CTCL) in dogs is a heterogeneous disease complex, which consists of nonepitheliotropic (NE) and epitheliotropic forms. These lymphomas are readily recognized by the presence of dominant populations of cytologically atypical lymphocytes. Objective – The objective of this study was to introduce the key features of inflamed NE-CTCL, which is easily confused with reactive, inflammatory histiocytic disease. Animals – Twenty-four dogs (mean age 7.5 years) presented with inflamed NE-CTCL. Lesions presented as nodules, plaques or masses. An initial diagnosis of cutaneous reactive histiocytosis (11 dogs) or histiocytic neoplasia (three dogs) was made by primary pathologists. Methods – Lesions were assessed by histology and immunohistochemistry to detect canine leukocyte antigens. Lesional genomic DNA was extracted and gene rearrangement analysis of the T-cell receptor γ locus was assessed. Results – The cutaneous lesions consisted of pleocellular infiltration of the dermis with variable extension into the subcutis. The lesions often surrounded vessels and adnexae. Epitheliotropism was minimal or lacking. Small lymphocytes, plasma cells and intermediate to large, cytologically atypical lymphocytes were scattered between prominent histiocytic infiltrates. Atypical lymphocytes often had marked variation in the intensity of CD3 expression. Molecular clonality analysis of the T-cell receptor γ locus revealed clonal expansion of T cells in 22 of 23 dogs tested. Conclusion – The recognition of inflamed NE-CTCL and its differentiation from cutaneous reactive histiocytosis depends on careful assessment of lymphocyte morphology and immunostaining patterns. Confirmation of the diagnosis is best accomplished by T-cell antigen receptor gene rearrangement analysis.

The exact function of T cells with the γδ-T-cell receptor is still poorly understood and their participation in different skin diseases is largely unknown. The goals of this study were to investigate the distribution of γδ-T cells in normal canine skin and mucocutaneous junctions, and to evaluate their frequency in different body locations. Skin samples were collected from 10 dogs. From each dog, 10 different skin regions were sampled. Two random 30 μm cryosections were used for immunohistochemistry. Each tissue was evaluated for the presence of T cells, αβ-T cells and γδ-T cells. The numbers of positive cells per volume of tissue were determined in the epidermis and superficial dermis of each sample using a 42-point square grid overlay. Accurate thickness of the tissue section was measured with an A2 axis stage micrometer. Results were analysed statistically and 1000 cells/mm3 were used as the threshold value. Independent from body location, the vast majority of γδ-T cells were observed in the epidermis. Significant occurrences of epidermal γδ-T cells were found in 50% of samples from the anorectal skin and eyelid, and in 25% of samples from the lip, interdigital skin and pinna. However

A previous study described cutaneous lymphocytosis (CL) in 23 cats. The process resembles cutaneous pseudolymphoma in humans, a heterogeneous group of benign reactive proliferations of well-differentiated lymphocytes in the skin of humans. Morphological and immunophenotypic characteristics do not offer reliable criteria to accurately predict the clinical outcome of feline CL or pseudolymphoma in humans. Presence of clonal cell populations is more consistent with a neoplastic process. In a previous study, feline CL lesions (20 cats) were evaluated for clonality using PCR, and only two cats had monoclonal T-cell populations. Because false-negative results may occur, the purpose of this study was to repeat the PCR using a revised primer set based on analysis of additional feline T-cell receptor γ (TCRγ) sequences. DNA was isolated from 29 skin lesions and six internal organs of 20 cats. DNA integrity was assessed by glyceraldehyde-3-phosphate dehydrogenase PCR. Polymerase chain reaction clonality was performed using the revised primer set specific for feline TCRγ, and duplicate samples were evaluated. The PCR products were assessed by heteroduplex analysis. Clonal rearrangement of TCRγ was detected in 14 cats (24 of 35 tissues: 21 of 29 skin lesions and three of six internal organs); eight of these cats are still alive and six were euthanized. Monoclonal populations were seen in three of five cats that had involvement of internal organs. These findings indicate that feline CL is best considered as a slowly progressive process which may be reactive, but often evolves into a low-grade indolent lymphoma. Funding: George H. Muller Fund for Research in Dermatology.