Second-generation Langerhans cells originating from epidermal precursors are essential for CD8+ T cell priming.

In vivo studies questioned the ability of Langerhans cells (LCs) to mediate CD8(+) T cell priming. To address this issue, we used intradermal immunization with plasmid DNA, a system in which activation of CD8(+) T cells depends on delayed kinetics of Ag presentation. We found that dendritic cells (DCs) located in the skin at the time of immunization have limited ability to activate CD8(+) T cells. This activity was mediated by a second generation of DCs that differentiated in the skin several days after immunization, as well as by lymph node-resident DCs. Intriguingly, CD8(+) T cell responses were not affected following treatment with clodronate liposomes, immunization of CCR2(-/-) mice, or local neutralization of CCL20. This suggests that local, rather than blood-derived, DC precursors mediate CD8(+) T cell priming. Analysis of DC differentiation in the immunized skin revealed a gradual increase in the number of CD11c(+) cells, which reached their maximum 2 wk after immunization. A similar differentiation kinetics was observed for LCs, with the majority of differentiating LCs proliferating in situ from epidermal precursors. By using B6/Langerin-diphtheria toxin receptor chimeric mice and LC ablation, we demonstrated that epidermal LCs were crucial for the elicitation of CD8(+) T cell responses in vivo. Furthermore, LCs isolated from lymph nodes 2 wk after immunization contained the immunization plasmid and directly activated Ag-specific CD8(+) T cells ex vivo. Thus, these results indicate that second-generation Ag-expressing LCs differentiating from epidermal precursors directly prime CD8(+) T cells and are essential for optimal cellular immune responses following immunization with plasmid DNA.

Characterization of multinucleated giant cells in synovium and subchondral bone in knee osteoarthritis and rheumatoid arthritis.

BACKGROUND: Multinucleated giant cells have been noticed in diverse arthritic conditions since their first description in rheumatoid synovium. However, their role in the pathogenesis of osteoarthritis (OA) or rheumatoid arthritis (RA) still remains broadly unknown. We aimed to study the presence and characteristics of multinucleated giant cells (MGC) both in synovium and in subchondral bone tissues of patients with OA or RA. METHODS: Knee synovial and subchondral bone samples were from age-matched patients undergoing total joint replacement for OA or RA, or non-arthritic post mortem (PM) controls. OA synovium was stratified by histological inflammation grade using index tissue sections. Synovitis was assessed by Krenn score. Histological studies employed specific antibodies against macrophage markers or cathepsin K, or TRAP enzymatic assay. RESULTS: Inflamed OA and RA synovia displayed more multinucleated giant cells than did non-inflamed OA and PM synovia. There was a significant association between MGC numbers and synovitis severity. A TRAP negative/cathepsin K negative Langhans-like subtype was predominant in OA, whereas both Langhans-like and TRAP-positive/cathepsin K-negative foreign-body-like subtypes were most commonly detected in RA. Plasma-like and foam-like subtypes also were observed in OA and RA synovia, and the latter was found surrounding adipocytes. TRAP positive/cathepsin K positive osteoclasts were only identified adjacent to subchondral bone surfaces. TRAP positive osteoclasts were significantly increased in subchondral bone in OA and RA compared to PM controls. CONCLUSIONS: Multinucleated giant cells are associated with synovitis severity, and subchondral osteoclast numbers are increased in OA, as well as in RA. Further research targeting multinucleated giant cells is warranted to elucidate their contributions to the symptoms and joint damage associated with arthritis.

Tuberculosis of the Cheek: A Rare Presentation.

Tuberculosis (TB) typically attacks the lungs. The oral lesions either primary or secondary are rarely seen and often overlooked by the clinician. More so, their atypical presentations make the diagnosis challenging; especially when they are present before the systemic symptoms become apparent. We report a case of primary tuberculosis in a 4 year old female child in a very uncommon location, the cheek. The timely diagnosis and antitubercular therapy resulted in complete resolution of the swelling within 6 months.

Cutting edge: microRNA regulation of macrophage fusion into multinucleated giant cells.

Cellular fusion of macrophages into multinucleated giant cells is a distinguishing feature of the granulomatous response to inflammation, infection, and foreign bodies (Kawai and Akira. 2011. Immunity 34: 637-650). We observed a marked increase in fusion of macrophages genetically deficient in Dicer, an enzyme required for canonical microRNA (miRNA) biogenesis. Gene expression profiling of miRNA-deficient macrophages revealed an upregulation of the IL-4-responsive fusion protein Tm7sf4, and analyses identified miR-7a-1 as a negative regulator of macrophage fusion, functioning by directly targeting Tm7sf4 mRNA. miR-7a-1 is itself an IL-4-responsive gene in macrophages, suggesting feedback control of cellular fusion. Collectively, these data indicate that miR-7a-1 functions to regulate IL-4-directed multinucleated giant cell formation.

The CD40-CD40L axis and IFN-γ play critical roles in Langhans giant cell formation.

The presence of Langhans giant cells (LGCs) is one of the signatures of systemic granulomatous disorders such as tuberculosis and sarcoidosis. However, the pathophysiological mechanism leading to LGC formation, especially the contribution of the T cells abundantly found in granulomas, has not been fully elucidated. To examine the role of T cells in LGC formation, a new in vitro method for the induction of LGCs was developed by co-culturing human monocytes with autologous T cells in the presence of concanavalin A (ConA). This system required close contact between monocytes and T cells, and CD4+ T cells were more potent than CD8+ T cells in inducing LGC formation. Antibody inhibition revealed that a CD40-CD40 ligand (CD40L) interaction and IFN-γ were essential for LGC formation, and the combination of exogenous soluble CD40L (sCD40L) and IFN-γ efficiently replaced the role of T cells. Dendritic cell-specific transmembrane protein (DC-STAMP), a known fusion-related molecule in monocytes, was up-regulated during LGC formation. Moreover, knock-down of DC-STAMP by siRNA inhibited LGC formation, revealing that DC-STAMP was directly involved in LGC formation. Taken together, these results demonstrate that T cells played a pivotal role in a new in vitro LGC formation system, in which DC-STAMP was involved, and occurred via a molecular mechanism that involved CD40-CD40L interaction and IFN-γ secretion.

Tuberculosis of the entheses.

PURPOSE: Tuberculosis of the osteoarticular system usually manifests as joint arthritis. There is no available English literature on the tubercular involvement of the enthesis (tendon-bone junction). METHODS: We performed a retrospective analysis on 14 patients with tuberculosis of the tendon-bone junction. Patients presenting with a sinus with or without presence of radiological evidence of bone destruction around the enthesis, and pain unresponsive to a trial of analgesics and physical therapy, were evaluated by closed or open biopsy for tuberculosis. A staging system is proposed for biopsy-proven tuberculosis of the enthesis. RESULTS: Between 2006 and 2010, we treated 14 patients with tuberculosis of the tendon-bone junction. Biopsy-proven cases of tuberculosis of the enthesis were administered anti-tubercular drugs for a period of one year. Sequestrectomy was performed in advanced lesions. The tendon-bone junction was rested until the features of its healing were clinically evident. The patients aged between 18 and 52 years were followed up for an average of 1.7 years after cessation of anti-tubercular drug therapy. They responded favourably, and none had recurrence of the disease. CONCLUSIONS: This study describes the tubercular involvement of the entheses, which heretofore has not been described in the literature. The rarity of its occurrence and lack of suspicion of an infectious aetiology in these locations frequently results in late diagnosis and incorrect initial treatment. This study also supports the "microtrauma theory" in the genesis of osteoarticular tuberculosis.

Frequent upregulation of cyclin D1 and p16 expression with low Ki-67 scores in multinucleated giant cells.

BACKGROUND/AIMS: Multinucleated giant cells are formed from the fusion of macrophages and are classified into foreign body-type giant cells (FBGCs), osteoclast-type giant cells (OCGCs) and Langhans-type giant cells (LHGCs). OCGCs display upregulated cyclin D1 expression with low Ki-67 activity. However, little is known about the expression of cell cycle regulators in the other types of multinucleated giant cells. We aimed to investigate the cell cycle status of multinucleated giant cells. METHODS: The immunohistochemical expressions of cyclin D1, p16(INK4a) and Ki-67 were analyzed in a total of 127 cases showing multinucleated giant cells. RESULTS: Cyclin D1 was overexpressed in 45 (88%) of 51 FBGC cases, 25 (86%) of 29 OCGC cases and 22 (47%) of 47 LHGC cases. p16(INK4a) showed diffuse nuclear and/or cytoplasmic overexpression in 45 (88%) of 51 FBGC cases, 27 (93%) of 29 OCGC cases and 24 (51%) of 47 LHGC cases. Ki-67 immunostaining was negative in almost all FBGC, OCGC and LHGC cases. CONCLUSION: This study demonstrates that FBGCs and OCGCs frequently show upregulation of cyclin D1 and p16(INK4a) expression with low Ki-67 scores. This suggests that multinucleated giant cells are arrested in the G1/S cell cycle transition.

Tumor necrosis factor-α can induce Langhans-type multinucleated giant cell formation derived from myeloid dendritic cells.

The formation of the rich cellular features of MGCs, where the nuclei are arranged circularly at the periphery of the cell (morphologically epithelioid; Langhans-type), is assumed to be associated with any granulomatous disease. The mechanism by which TNF controls the formation of human MGCs in vitro was investigated, focusing on the effect of the TNF-neutralizing antibody. Peripheral blood monocytes were isolated with mAb-coated immunologic magnetic beads and cultured for 10 days in the presence of 20 ng/mL GM-CSF and 10 ng/mL IL-4. These cells were further incubated in the presence of TNF-α with/without its blockade antibodies for 14 days. Myeloid DCs can be generated from peripheral blood monocytes, and both IL-4 and GM-CSF can provide sufficient stimulus for their differentiation. The formation of MGC can be induced in the presence of TNF-α. This reaction was prohibited by the presence of the TNF-neutralizing antibody but not by the presence of anti-TNF receptor II antibody. The activation of Rho and focal adhesion kinases induced by TNF-α stimulation might be linked to cell assembling and the formation of Langhans-type MGCs. MGCs can produce only small amounts of superoxide anions compared to isolated macrophages such as myeloid DCs.

Cellular, Molecular, and Immunological Characteristics of Langhans Multinucleated Giant Cells Programmed by IL-15.

Langhans multinucleated giant cells (LGCs) are a specific type of multinucleated giant cell containing a characteristic horseshoe-shaped ring of nuclei that are present within granulomas of infectious etiology. Although cytokines that trigger macrophage activation (such as IFN-γ) induce LGC formation, it is not clear whether cytokines that trigger macrophage differentiation contribute to LGC formation. Here, we found that IL-15, a cytokine that induces M1 macrophage differentiation, programs human peripheral blood adherent cells to form LGCs. Analysis of the IL-15‒treated adherent cell transcriptome identified gene networks for T cells, DNA damage and replication, and IFN-inducible genes that correlated with IL-15 treatment and LGC-type multinucleated giant cell formation. Gene networks enriched for myeloid cells were anticorrelated with IL-15 treatment and LGC formation. Functional studies revealed that T cells were required for IL-15‒induced LGC formation, involving a direct contact with myeloid cells through CD40L-CD40 interaction and IFN-γ release. These data indicate that IL-15 induces LGC formation through the direct interaction of activated T cells and myeloid cells.

Cystic neutrophilic granulomatous mastitis: an update.

Cystic neutrophilic granulomatous mastitis (CNGM) is a rare subtype of granulomatous mastitis with a highly distinct histological pattern often associated with Corynebacterium species. CNGM is characterised by suppurative lipogranulomas that are composed of central lipid vacuoles rimmed by neutrophils and an outer cuff of epithelioid histiocytes. Some of the lipid vacuoles may contain sparse, rod-shaped, gram-positive bacilli that can be easily missed or dismissed. The surrounding mixed inflammatory infiltrate contains Langhans-type giant cells, lymphocytes and neutrophils. CNGM occurs in reproductive age women with a history of pregnancy and typically presents as a palpable mass that can be painful. CNGM has many mimickers, most significantly breast carcinoma. In many cases, CNGM has significant pathological and clinical overlap with other forms of granulomatous mastitis. Given the association with Corynebacterium species, early diagnosis of CNGM is essential in offering patients the most appropriate treatment. Prolonged antibiotic therapy specifically directed to corynebacteria is required, sometimes even beyond resolution of clinical symptoms. This comprehensive review of the existing literature on CNGM describes clinical-pathological features, microbiological findings, challenges associated with the microscopic differential diagnosis, clinical implications of this diagnosis and emerging treatment options. Morphological criteria and suggested comments to convey the degree of diagnostic certainty are also proposed for standard pathology reporting.

More experiences with the Tzanck smear test: cytologic findings in cutaneous granulomatous disorders.

BACKGROUND: Granulomatous dermatitis is a distinctive histopathologic cutaneous reaction pattern against various infectious and noninfectious agents. Cytologically, granulomatous dermatitis shows granulomas and multinucleated giant cells. Various etiologic agents of granulomatous diseases can also be identified. OBJECTIVE: We aimed to investigate Tzanck smear findings in granulomatous skin diseases. METHODS: Patients who had granulomas and/or multinucleated giant cells of Langhans, foreign body- and/or Touton type in Tzanck smear tests were included in the study. In these patients, Tzanck preparations were then further evaluated for additional cytologic findings. Samples stained with May-Grünwald-Giemsa stain were evaluated by the same dermatologist throughout the study. In some patients, methylene blue, Gram and/or Erlich-Ziehl-Nielsen stains were also performed. In all of the study cases, the final diagnosis was established after the evaluation of clinical and laboratory findings (including, when appropriate, potassium hydroxide examination; bacterial, leishmanial, and fungal cultures; histopathology; tuberculosis and leishmania polymerase chain reaction). We also calculated the sensitivity and specificity of the Leishman-Donovan body for cutaneous leishmaniasis. RESULTS: Over a 2-year period, 94 of 950 patients (9.9%) in whom Tzanck smear tests were performed had cytologic findings consistent with a granulomatous reaction. In 74 (78.7%) and 20 (21.3%) patients, the granulomatous reaction was due to infectious and noninfectious causes, respectively. Infectious causes included cutaneous leishmaniasis in 65 patients (87.8%), candidal granuloma in two patients, botyromycosis in two patients, and aspergillosis, blastomycosis, mucormycosis, leprosy, and cutaneous tuberculosis in one patient each. In 58 of 74 patients (78.4%) with infectious granulomatous dermatitis, the causes of the granulomas were identified. Noninfectious granulomatous reactions were due to granuloma annulare in 7 patients, sarcoidosis in 5 patients, a foreign body in 4 patients, necrobiosis lipoidica in 2 patients, and juvenile xanthogranuloma in 2 patients. In 17 of 20 patients (85%) with noninfectious granulomatous reactions, the cytologic findings were characteristic of the final diagnoses. The sensitivity and specificity of Leishman-Donovan bodies for cutaneous leishmaniasis were 76.9% and 100%, respectively. LIMITATIONS: All of the samples were evaluated by the same dermatologist throughout the study; therefore no comment could be made regarding the reliability of the Tzanck smear test. In addition, the sensitivity and specificity of Tzanck smear test findings for diseases other than cutaneous leishmaniasis could not be calculated because of an insufficient number of patients. CONCLUSION: The Tzanck smear test may be a useful diagnostic tool for certain granulomatous skin diseases.

Thalidomide prevents formation of multinucleated giant cells (Langhans-type cells) from cultured monocytes: possible pharmaceutical applications for granulomatous disorders.

Thalidomide is an effective drug for chronic inflammatory diseases, but the mechanism underlying its immunomodulatory action remains uncertain. Thalidomide has been reported to clinically improve chronic inflammatory granulomatous disorders. In such disorders, the granulomas consist of epithelioid cells, scattered lymphocytes and multinucleated giant cells (MNGC; Langhans-type cells). The present experimental approach permitted the reproduction of MNGC formation from peripheral blood monocytes and examination of thalidomides effect on it. MNGC can be effectively generated from monocytes cultured in the presence of interleukin-4 (IL-4) and macrophage colony-stimulating factor(M-CSF) for 14 days. Thalidomide can inhibit the formation of MNGC in a dose-dependent manner. MNGC formation was partly inhibited by the presence of neutralizing TNF-alpha antibody in the responses induced by IL-4 and M-CSF. Autocrinal TNF-alpha production and modulation of cadhelin expression to regulate cell adhesion might be involved in this inhibitory action of thalidomide. Our results support thalidomides clinical efficacy in the treatment of chronic granulomatous disorders (granulomatosis).

Granuloma in sputum cytology of pulmonary tuberculosis: a case report.

BACKGROUND: Presence of epithelioid cell granuloma and Langhans' giant cells in sputum cytology in cases of pulmonary tuberculosis is of very uncommon occurrence. Only a few reports could be found in the English-language literature. CASE: A 73-year-old man, a chronic smoker for 50 years, reported to the medical out-patient department with complaints of cough and significant weight loss for the past 1 year. Routine sputum cytology revealed epithelioid cell granuloma along with Langhans' giant cells. Ziehl-Neelsen stain showed presence of multiple acid-fast bacilli (AFB). Chest radiography showed opacity of the airways and areas of cavitations in bilateral parahilar location and diffuse nodular opacity in bilateral lung fields. CONCLUSION: Albeit of very rare occurrence, presence of epithelioid cell granuloma and Langhans' giant cells, along with demonstration of AFB in routine sputum cytology, is capable of providing a conclusive diagnosis in appropriate clinical context, obviating the need of additional investigation.

Why does tuberculosis lead to specific inflammation?

When Mycobacterium tuberculosis infects humans, about 20% of those infected actually develop tuberculosis (TB). In Japan, the incidence of TB in 2008 was 24,760 cases (19.4/100,000 persons) and the rate has been decreasing gradually, but is still higher than in the USA, Holland, and Belgium, for example. Histologically, tuberculosis displays exudative inflammation, proliferative inflammation and productive inflammation depending on the time course. In productive inflammation, granulomatous lesions with necrotic centers are formed. The typical granulomas consist of epithelioid macrophages, Langhans' multinucleated giant cells, lymphocytes and fibroblasts, and the process of their formation involves many cytokines, chemokines and transcription factors. These findings have been derived primarily from animal experiments utilizing an airborne infection apparatus. The conditions for airborne infection have been described in detail elsewhere. This mini-review focuses on what has been found through animal experiments, and also indicates areas for which data are not currently available.

Interleukin-22 receptor 1 is expressed in multinucleated giant cells: A study on intestinal tuberculosis and Crohn's disease.

BACKGROUND: It is challenging to distinguish intestinal tuberculosis from Crohn's disease due to dynamic changes in epidemiology and similar clinical characteristics. Recent studies have shown that polymorphisms in genes involved in the interleukin (IL)-23/IL-17 axis may affect intestinal mucosal immunity by affecting the differentiation of Th17 cells. AIM: To investigate the specific single-nucleotide polymorphisms (SNPs) in genes involved in the IL-23/IL-17 axis and possible pathways that affect susceptibility to intestinal tuberculosis and Crohn's disease. METHODS: We analysed 133 patients with intestinal tuberculosis, 128 with Crohn's disease, and 500 normal controls. DNA was extracted from paraffin-embedded specimens or whole blood. Four SNPs in the IL23/Th17 axis (IL22 rs2227473, IL1ß rs1143627, TGFß rs4803455, and IL17 rs8193036) were genotyped with TaqMan assays. The transcriptional activity levels of different genotypes of rs2227473 were detected by dual luciferase reporter gene assay. The expression of IL-22R1 in different intestinal diseases was detected by immunohistochemistry. RESULTS: The A allele frequency of rs2227473 (P = 0.030, odds ratio = 0.60, 95% confidence interval: 0.37-0.95) showed an abnormal distribution between intestinal tuberculosis and healthy controls. The presence of the A allele was associated with a higher IL-22 transcriptional activity (P < 0.05). In addition, IL-22R1 was expressed in intestinal lymphoid tissues, especially under conditions of intestinal tuberculosis, and highly expressed in macrophage-derived Langhans giant cells. The results of immunohistochemistry showed that the expression of IL-22R1 in patients with Crohn's disease and intestinal tuberculosis was significantly higher than that in patients with intestinal polyps and colon cancer (P < 0.01). CONCLUSION: High IL-22 expression seems to be a protective factor for intestinal tuberculosis. IL-22R1 is expressed in Langhans giant cells, suggesting that the IL-22/IL-22R1 system links adaptive and innate immunity.

Low levels of alpha-synuclein in peripheral tissues are related to clinical relapse in relapsing-remitting multiple sclerosis: a pilot cross-sectional study.

The protein alpha-synuclein (α-Syn) has been linked to neuroinflammatory conditions. We investigated whether the presence of α-Syn in peripheral tissues is a surrogate of brain inflammatory status in a small group of relapsing-remitting multiple sclerosis (RRMS) patients in a pilot cross-sectional study. Skin biopsies and peripheral blood were sampled from 34 healthy controls and 23 MS patients for measurement of α-Syn levels. Within the RRMS group 15 patients were in remission, and 8 patients were in the relapsing phase. The protein α-Syn was evaluated by means of immunohistochemistry and flow cytometry in skin and nucleated blood cells, respectively. In the skin, α-Syn levels were lower in relapsing MS than in the other groups, both in positive area (p = .021) and staining intensity (p = .004). In blood, the percentage of α-Syn-positive lymphocytes and monocytes were not statistically different between study groups. Moreover, the use of systemic steroids did not affect α-Syn positivity in MS-relapse patients. Finally, epidermic Langerhans cells did not stain positively for α-Syn. Overall, the levels of α-Syn positivity were lower in inflammatory relapse of RRMS patients when measured in peripheral tissues. We discuss the role of α-Syn levels in inflammation according to the obtained results.

Generalized sarcoidosis in two horses.

Equine sarcoidosis is a rare disorder usually characterized by exfoliative dermatitis, moderate to severe wasting, and sarcoidal granulomatous inflammation of multiple organ systems. It has an unknown aetiopathogenesis. The condition is not related to equine sarcoid. This case report describes generalized cutaneous and systemic sarcoidosis in an 11-year-old Trakehner mare (case A) and in a 7-year-old Dutch Warmblood gelding (case B). Case A was presented with cutaneous sarcoidosis on the head and body and was diagnosed on the basis of histological examination of skin. Case B presented with multiple subcutaneous nodules (2-15 cm in diameter) and the diagnosis was established at postmortem examination. Both horses showed distinctive histology of the skin with extensive lymphohistiocytic infiltration and Langhans-type multinucleated giant cells. Haematology and biochemistry revealed a normal total white blood cell count with a right shift in both horses. Case B was anaemic and had a slightly elevated total protein concentration with hyperglobulinaemia. Both horses were unresponsive to corticosteroids and were euthanized.

Tuberculosis cutánea esporotricoide en la Amazonía peruana: reporte de caso / Sporotrichoid cutaneous tuberculosis in the peruvian amazon: case report

RESUMEN La tuberculosis cutánea es una presentación rara de la infección por Mycobacterium tuberculosis. Se presenta el caso de una mujer sin antecedentes médicos de importancia, con un tiempo de enfermedad de año y medio, caracterizado por lesiones tipo esporotricoide, con diseminación linfocutánea en miembro superior derecho, de evolución lentamente progresiva. Se realizó un estudio histopatológico encontrándose células gigantes tipo Langhans y escasa necrosis. El paciente recibió terapia de esquema sensible antituberculoso, con evolución favorable.

ABSTRACT Cutaneous tuberculosis is a rare presentation of Mycobacterium tuberculosis infection. We present the case of a woman without important medical history, with a disease period of one year and a half, characterized by sporotrichoid-like lesions, with lymphocutaneous dissemination in the right upper limb, and with slowly progressive evolution. The histopathological tests revealed Langhans type giant cells and scarce necrosis. The patient received therapy with a sensitive antituberculous scheme, and evolved favorably.

Primary pituitary tuberculosis

Tuberculosis is an infectious disease that involves any organ. However, the primary pituitary tuberculosis is an extremely rare disease. Intracranial tuberculomas account for 0.15-5% of intracranial space-occupying lesions, of which, pituitary as the primary site is unusual, and easily misdiagnosed as pituitary adenoma. In this setting, the late diagnosis can result in permanent endocrine dysfunction. We report the case of a 50-year-old woman who presented to the neurosurgery outpatient department with complaints of progressively increasing headache and diminished vision over the last year. On the clinical examination, the patient was conscious and oriented. The routine hematological and biochemical workup showed an increased erythrocyte sedimentation rate (ESR) and increased prolactin levels. The radiological working diagnosis was consistent with pituitary macroadenoma. No other radiological and/or clinical clue that could elicit the suspicion of pulmonary or extrapulmonary lesions of tuberculosis was found. The transsphenoidal endonasal tumor excision was done. The histopathology showed numerous epithelioid cell granulomas, Langhans giant cells along with scant necrosis. Ziehl Neelsen staining demonstrated acid-fast bacilli, and the final diagnosis of pituitary tuberculoma was made. We report this rare case of pituitary lesion that may be included in the differential diagnosis of sellar lesions to avoid unnecessary surgical interventions, especially in regions where the disease is endemic.

Muramyl dipeptide and mononuclear cell supernatant induce Langhans-type cells from human monocytes.

Muramyl dipeptide (MDP) in bacterial cell walls reportedly evokes epithelioid cell granulomas. We examined its effects on multinucleated-giant-cell (MGC) formation from monocytes. Supernatant of concanavalin A-stimulated peripheral blood mononuclear cells (conditioned medium) generated MGCs from monocytes. MDP significantly increased the fusion index of Langhans-type MGCs (LGCs) but did not affect total MGCs. N-Acetylmuramyl-L-alanyl-L-isoglutamine, an MDP analogue, had no effect on MGC formation. MGCs were produced by conditioned medium from CD14(++)/CD16(-) monocytes. MDP enhanced the LGC fusion index from CD14(++)/CD16(-) monocytes. MGCs were not produced from CD14(+)/CD16(+) monocytes or immature dendritic cells induced by granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL) 4 and only weakly produced from macrophage (M)-CSF- or GM-CSF-induced macrophages. Added MDP did not generate MGCs from CD14(+)/CD16(+) monocytes or dendritic cells but enhanced LGC formation from macrophages. Because IFN-gamma, IL-3, and GM-CSF reportedly are important in LGC induction, we added anti-IFN-gamma, anti-IL-3, or anti-GM-CSF monoclonal antibody (mAb) concomitantly to the monocyte culture treated with conditioned medium alone or plus MDP. Anti-IFN-gamma mAb completely abrogated MGC generation, whereas anti-GM-CSF and anti-IL-3 mAbs significantly inhibited LGCs. These findings suggest that CD14(++)/CD16(-) monocytes are fused to form LGCs by MDP derived from granulomatous-disease-causing pathogens with inflammatory mediators such as IFN-gamma, IL-3, and GM-CSF.