A comparison of conjunctival and nonocular dendritic cells utilizing new monoclonal antibodies

Nonosseous Periocular Manifestations of Langerhans Cell Histiocytosis: A Case Report and Systematic Review

PURPOSE

Langerhans cell histiocytosis (LCH) is a disorder of dendritic cell proliferation that typically involves bone. It can be diagnostically challenging when LCH presents without bony involvement, leading to delays in diagnosis and treatment. In this study, the periocular manifestations of LCH in cases where the underlying orbital bones are not involved are described through a systematic review.

METHODS

A systematic review of the literature was performed to capture all cases of LCH that involved the periocular region but not the underlying orbital bones. These included LCH cases that involved the periocular skin, the ocular surface, and the orbital tissue. The authors also highlight an additional case where LCH presented with periocular edema and multifocal, nodular conjunctival lesions.

RESULT

This review illustrates that LCH rarely presents with periocular infiltration without orbital bone involvement. In these atypical cases, LCH can present as an eyelid mass, a chalazion-like lesion, generalized periocular swelling, ocular surface lesions, or infiltration of any orbital structure. Ocular surface LCH has a higher rate of recurrence than other periocular LCH. Orbital LCH can involve any tissue including extraocular muscles, the lacrimal gland, or indistinct areas within the orbit.

CONCLUSIONS

LCH is a clinicopathologic diagnosis. Although most cases involve the bone, any soft tissue can be involved. Biopsy is required to confirm the diagnosis of this heterogeneous disease.

Plasmacytoid dendritic cells in the eye

Plasmacytoid dendritic cells (pDCs) are a unique subpopulation of immune cells, distinct from classical dendritic cells. pDCs are generated in the bone marrow and following development, they typically home to secondary lymphoid tissues. While peripheral tissues are generally devoid of pDCs during steady state, few tissues, including the lung, kidney, vagina, and in particular ocular tissues harbor resident pDCs. pDCs were originally appreciated for their potential to produce large quantities of type I interferons in viral immunity. Subsequent studies have now unraveled their pivotal role in mediating immune responses, in particular in the induction of tolerance. In this review, we summarize our current knowledge on pDCs in ocular tissues in both mice and humans, in particular in the cornea, limbus, conjunctiva, choroid, retina, and lacrimal gland. Further, we will review our current understanding on the significance of pDCs in ameliorating inflammatory responses during herpes simplex virus keratitis, sterile inflammation, and corneal transplantation. Moreover, we describe their novel and pivotal neuroprotective role, their key function in preserving corneal angiogenic privilege, as well as their potential application as a cell-based therapy for ocular diseases.

TFOS DEWS II pathophysiology report

The TFOS DEWS II Pathophysiology Subcommittee reviewed the mechanisms involved in the initiation and perpetuation of dry eye disease. Its central mechanism is evaporative water loss leading to hyperosmolar tissue damage. Research in human disease and in animal models has shown that this, either directly or by inducing inflammation, causes a loss of both epithelial and goblet cells. The consequent decrease in surface wettability leads to early tear film breakup and amplifies hyperosmolarity via a Vicious Circle. Pain in dry eye is caused by tear hyperosmolarity, loss of lubrication, inflammatory mediators and neurosensory factors, while visual symptoms arise from tear and ocular surface irregularity. Increased friction targets damage to the lids and ocular surface, resulting in characteristic punctate epithelial keratitis, superior limbic keratoconjunctivitis, filamentary keratitis, lid parallel conjunctival folds, and lid wiper epitheliopathy. Hybrid dry eye disease, with features of both aqueous deficiency and increased evaporation, is common and efforts should be made to determine the relative contribution of each form to the total picture. To this end, practical methods are needed to measure tear evaporation in the clinic, and similarly, methods are needed to measure osmolarity at the tissue level across the ocular surface, to better determine the severity of dry eye. Areas for future research include the role of genetic mechanisms in non-Sjögren syndrome dry eye, the targeting of the terminal duct in meibomian gland disease and the influence of gaze dynamics and the closed eye state on tear stability and ocular surface inflammation.

In Vivo Confocal Microscopy of Normal Conjunctiva and Conjunctivitis

PURPOSE

To analyze the appearance of normal conjunctiva and conjunctival inflammation by in vivo confocal microscopy.

METHODS

Conjunctiva of 15 normal patients and 21 patients with conjunctivitis including bacterial, papillary, follicular, granulomatous, and cicatrizing disease were analyzed by the Heidelberg retina tomograph (HRTII)/Rostock cornea modul (RCM).

RESULTS

Scans of normal bulbar and tarsal conjunctiva corresponded well to the established anatomy except for a prominent, thickened epithelial basement membrane observed by in vivo microscopy. Presumed goblet cells were visible throughout the conjunctival epithelium. Adenoid structures and hair follicles were discernible in the tarsal conjunctiva in vivo. Conjunctival perfusion could be observed directly. Acute and chronic inflammatory cells, conjunctival papillary, and follicular reactions, as well as conjunctival cicatrization, could be discriminated. In a patient with conjunctival granuloma, in vivo confocal microscopy disclosed suture material inside the lesion.

CONCLUSION

Confocal microscopy using near-infrared laser light is a useful new tool in the analysis of conjunctival tissue in vivo. It is a valuable aid in the differential diagnosis of conjunctival inflammation and thus may guide therapeutical decisions.

Effect of topical dexamethasone and ciprofloxacin on bacterial flora of healthy conjunctiva

PURPOSE

To investigate the effects of topical dexamethasone and ciprofloxacin, alone and in combination, on the colony counts of conjunctival bacterial flora of healthy subjects.

METHODS

A total of 100 healthy subjects were randomly divided into four groups, consisting of 25 subjects each. Group 1 was treated with dexamethasone phosphate 0.1% (Maxidex). Group 2 was treated with ciprofloxacin 0.3% (Ciloxan) and Group 3 with a combination of these drugs. Group 4 received artificial tear solution (Tears Naturale) and served as control. The drops were administered one drop every 1 min. A pretreatment culture and recultures at 30, 90, and 180 min after application of final drops were performed on all subjects. The bacterial growth was evaluated in a quantitative manner. All cultures were performed in a double-masked fashion. ANOVA test was used for statistical analyses.

RESULTS

While there was no significant difference among mean number of pretreatment colonies between the groups (P=0.85); the differences at 30, 90, and 180 min were statistically significant (P<0.001). During the study there was no statistically significant change in colony counts in Groups 1 and 4 (P=0.66 and 0.55, respectively). The colony count numbers decreased significantly at 30 and 90 min in Group 2 (P<0.001 and P=0.004) and at 30 min in Group 3 (P=0.002).

CONCLUSION

Topically applied dexamethasone did not cause a significant change in colony counts of the healthy conjunctiva. Both ciprofloxacin and a combination of ciprofloxacin and dexamethasone were effective in the reduction of bacterial ocular flora.

Langerhans cell-like dendritic cells in the cornea, tongue and oesophagus of the chicken (Gallus gallus)

Langerhans cells are dendritic leucocytes which reside mainly within stratified squamous epithelia of skin and mucosa. Their visualization requires the use of ATPase histochemistry, electron microscopy for identifying the unique trilaminar cytoplasmic organelles (the Langerhans cell granules or Birbeck granules), and the expression of major histocompatibility complex class II molecules. Following uptake of antigen, Langerhans cells migrate via the afferent lymphatics to the lymph nodes and undergo differentiation from an antigen-processing cell to an antigen-presenting cell. Using the same approach as that employed in previous studies for the identification of chicken epidermal Langerhans cells, we show here the presence of ATPase-positive and major histocompatibility complex class II-positive Langerhans cell-like dendritic cells at the mucosal surface of the eye, tongue and oesophagus of the chicken. Ultrastructurally, these cells qualified as Langerhans cells except that they lack Langerhans cell granules. Thus, as in mammalian skin and mucosa, chicken mucosa contains mucosal dendritic cells with morphological and phenotypical features for the engagement of incoming antigens within epithelium and lamina propria.

Langerhans cell histiocytosis with orbital involvement

PURPOSE

To review three cases of Langerhans cell histiocytosis with orbital involvement that represent a significantly excessive incidence of this rare disease in one community. Current diagnostic criteria and therapeutic modalities related to Langerhans cell histiocytosis are reviewed.

METHODS

Case reports. We present clinical, radiologic, histopathologic, and epidemiologic information on three patients with Langerhans cell histiocytosis.

RESULTS

All three children, born within 18 months of one another, manifested rapidly progressive unilateral proptosis at age 2 years. By computed tomography, all had moderately enhancing lesions with involvement of the sphenoid bone and lateral orbit as well as the temporal lobe of the brain. All patients were treated with a combination of vincristine and prednisone, with variable resolution of their lesions. The occurrence of three cases in children born in Nogales, Arizona/ Mexico, suggests an incidence rate of 40 per million, which is approximately 26 times the expected rate (P = .0001).

CONCLUSIONS

The extraordinarily high incidence and the concentration of cases in both time and space of this cluster implies that Langerhans cell histiocytosis may be a sentinel disease for unusual environmental exposures.

IgE, IgE receptors, and other immunocytochemical markers in atopic and nonatopic patients with vernal keratoconjunctivitis

BACKGROUND

Vernal keratoconjunctivitis (VKC) often is associated with atopy but a considerable part of the patients lack evidence of specific hypersensitivity. An immunocytochemical study was undertaken with the aim of detecting possible differences in the tissue inflammatory response between atopic and nonatopic subjects with VKC.

METHODS

Conjunctival biopsy specimens from six atopic and three nonatopic subjects with VKC (age range, 7-17 years) and eight healthy control subjects (age range, 3-15 years) were analyzed with a panel of monoclonal and polyclonal antibodies.

RESULTS

No distinct differences in cell counts between atopic and nonatopic subjects with VKC were observed. Vernal keratoconjunctivitis specimens as a whole showed higher counts than control specimens for CD3+, CD4+, HLA-DR+, CD38+, EG2+, CD68+, IgE+, FC epsilon RI+, IgA+, IgG+, and IgM+ cells in the substantia propria; and for CD1a+, IgE+, and EG2+ cells in the epithelium.

CONCLUSIONS

Because the number of cells expressing CD4, EG2, IgE, and the high-affinity receptor for IgE, all of which are considered relevant in infiltrates of allergic conditions, were similar in atopic and nonatopic subjects, the authors conclude that the role of allergen-specific IgE sensitization in the pathogenesis of VKC remains unclear.

Potential antigen-presenting cells in normal extraocular muscles demonstrated with double immunoenzyme staining

Antigen-presenting cells are of crucial importance for the initiation and regulation of regional immune responses. In a previous study, indirect morphological evidence that morphologically normal human orbital tissues contain HLA-DR-positive macrophages, which may represent antigen-presenting cells, has ben obtained. In the present study, these cells were characterized in detail using double immunoenzyme staining techniques with monoclonal antibodies directed against several well-characterized monocyte/macrophage markers and against HLA-DR gene products. The orbital muscular tissues appear to contain numerous HLA-DR, monocyte/macrophage marker double-stained cells, which are considered to be potential antigen-presenting cells. The cells are widely distributed in the connective tissue of all the orbital muscular tissues studied and consist of several subsets with different phenotypes. Furthermore, site-specific differences were shown between recti muscles and the levator/Müller's muscles with respect to the distribution of HLA-DR and one monocyte/macrophage marker (OKM5). Many of the orbital antigen-presenting cells appear to be of the dendritic type and are considered to be of major importance in regulating local orbital immunity.

T cells and trachoma. Their role in cicatricial disease

Frozen sections of tarsoconjunctival biopsies with trachomatous scarring from 14 black adults undergoing corrective surgery for trichiasis, and "normal" tissue from three postmortem controls, were immunohistochemically stained for the major T- and B-cell subsets, and for macrophages and monocytes. T cells outnumbered B cells by 2 to 17 times, and macrophages and monocytes by approximately 20 times in all specimens. Biopsies were categorized as "inflamed" if a cumulative inflammatory score of cellular staining in the substantia propria with CD4, CD8, and OKM1 monoclonal antibodies was greater than that of control tissues. CD4+ lymphocytes predominated over CD8+ lymphocytes in 5 of 7 inflamed biopsies, whereas CD8+ lymphocytes predominated over CD4+ lymphocytes in 5 of 7 noninflamed biopsies. Lymphoid aggregates were present in five inflamed biopsies, but lacked germinal centers, centrally located B cells, or parafollicular T cells typical of the acute stage of trachoma. CD4+ and CD8+ lymphocytes also were observed in the epithelium and lumen of Meibomian glands. These observations indicate that the inflammatory infiltrate of the tarsoconjunctiva in the cicatricial stage of trachoma is comprised predominantly of T cells, and suggests that T cells may be involved in the genesis of tarsal thickening and conjunctival scarring seen in the later stages of trachoma.

Ocular rosacea. A histologic and immunopathologic study

Acne rosacea is an idiopathic dermatologic disease that frequently produces conjunctival inflammation. The authors studied the histology and immunopathology of epibulbar conjunctival biopsy specimens from eight patients with ocular rosacea and compared the findings with those from conjunctiva from 13 normal individuals. The conjunctival epithelium in ocular rosacea was attenuated and infiltrated by inflammatory cells, mainly T-helper/inducer (CD4) cells, phagocytic cells, and antigen-presenting (CD14, Mac-1) cells. The difference between the normal control group and the rosacea group in the number of mononuclear cells forming these populations was statistically significant (P less than 0.01). The substantia propria of the rosacea specimens contained large subepithelial infiltrates of chronic inflammatory cells, and in some cases frank granuloma formation was evident. There was an overall mean increase of nearly all cell types, but especially of T-helper cells in the rosacea specimens compared with the controls. Interestingly, T-helper/inducer (CD4) cells, which were outnumbered by the T-suppressor (CD8) cells in the normal conjunctival epithelium (CD4/CD8 = 0.85), outnumbered the CD8-positive cells in the rosacea specimens (CD4/CD8 = 1.6). There also was a 3.5-fold increase of the CD4/CD8 ratio in the rosacea conjunctival stroma compared with the normal specimens. The mechanism involved in rosacea conjunctival inflammation resembles a type IV hypersensitivity reaction.

Langerhans cells of human mucosa

The ontogeny of human LC and their presence in all Malpighian epithelia underline their important role in immunoregulation of the skin and mucous membranes. LC are also found in buccal and esophageal mucosa, in cornea and conjunctiva, in pulmonary, vesical, vaginal and cervical epithelia as well as in placenta villi. In all these Malpighian epithelia, the presence of DR + LC is necessary and essential for the surveillance function against allergo-antigens and the emergence of neo-antigens associated with malignant transformations.

The role of the limbus in corneal allograft rejection

The state of the recipient peripheral cornea and limbus exerts a strong influence on subsequent corneal graft survival. In particular, graft outcome is influenced by the number of dendritic cells (Langerhans cells) that have infiltrated the graft bed from the limbus. The number of dendritic cells present in the donor button also affects subsequent graft survival.

Immunophenotypic analysis of the inflammatory infiltrate in ocular cicatricial pemphigoid. Further evidence for a T cell-mediated disease

Ocular cicatricial pemphigoid (OCP) is characterized by the deposition of immunoglobulin and complement along the conjunctival epithelial basement membrane zone (BMZ). In order to further elucidate the cellular populations of the local inflammatory infiltrates, the authors used a panel of monoclonal antibodies in cryostat tissue sections to delineate T cell subsets, B lymphocytes, dendritic cells, and macrophages in six patients with OCP. In comparison with matched controls of the epibulbar conjunctiva, the authors discovered a threefold increase in T lymphocytes within the epithelium and a 20-fold increase within the substantia propria. In contrast with the normal-standing population of conjunctival T lymphocytes, there were activated interleukin 2 receptor (IL-2R)-positive lymphocytes in both the epithelium and the substantia propria. Macrophages were the second most common cells in the substantia propria, accounting for 12.7% of the mononuclear population--a threefold increase over the normal percentage. B cells and plasma cells, normally absent from epibulbar conjunctiva, were the next most prominent populations, constituting 6.9 and 4.6%, respectively, of all mononuclear cells. Dendritic cells which process antigen locally constituted only 1.2% of the mononuclear cell population, but were increased 25-fold over normal controls. By elaborating cytokines that promote fibroplasia, the T cells in OCP may be effector cells along with macrophages and other inflammatory cells in bringing about scarification of the substantia propria, and may furthermore be responsible for an immunoregulatory defect that allows local B lymphocytes to produce autoantibodies to the BMZ.

Infantile subconjunctival and anterior orbital fibrous histiocytoma. Ultrastructural and immunohistochemical studies

A fleshy, polypoidal and partially lobulated lesion that protruded between the eyelids from the medial caruncular region and that infiltrated the contiguous anterior orbital tissues developed over 1 month in a 9-month-old infant. The microscopic features of the tumor included a plump spindle cell population, more polygonal cells, early xanthoma cell transformation, infiltrating lymphocytes and eosinophils, and multinucleated giant cells, the last not exhibiting classic Touton characteristics. The histopathologic differential diagnosis ranged among fibrous histiocytoma, juvenile xanthogranuloma, and eosinophilic granuloma (histiocytosis-X). Results of electron microscopy disclosed abundant rough-surfaced endoplasmic reticulum, a paucity of lysosomes, and no Langerhans' (Birbeck) granules. Immunohistochemistry corroborated the fibrohistiocytic nature of the tumor, because histochemical stains for the enzymes alpha-1-antichymotrypsin and lysozyme, and monoclonal or polyclonal antibodies against common leukocytic antigen and S-100 protein, were negative--whereas they would have been expected to be positive in various combinations in the different histiocytic proliferations. Vimentin was identified in the tumor cells; this is an intermediate cytoplasmic filament almost always present in mesenchymal proliferations. The distinctions between fibrous histiocytomas of stromal cell origin and true histiocytic proliferations of bone marrow cell provenance are explored.

The immunoarchitecture of the normal human lacrimal gland. Relevancy for understanding pathologic conditions

To delineate the immunoarchitecture of the normal human lacrimal gland, monoclonal antibodies that detect B- and T-lymphocyte, macrophage, and dendritic cell lineage, subset, and differentiation-associated antigens were used in combination with highly sensitive tissue-section immunoperoxidase techniques. Plasma cells, identified with monoclonal antibody OKT10, represented the predominant mononuclear cell population, accounting for 53.9% of all mononuclear cells present. A qualitative study of plasma cell cytoplasmic immunoglobulin heavy-chain expression in deparaffinized, formalin-fixed tissue sections showed that the vast majority of these plasma cells contained IgA. Rare plasma cells contained IgG, IgM, or IgD. T-cells, identified with monoclonal antibody OKT3, represented the second most common cell type in the normal human lacrimal gland, accounting for 40.3% of all mononuclear cells present. T cells were located predominantly in lymphocytic foci and singly in the interstitium. T8 antigen-positive (suppressor/cytotoxic) T cells predominated over T4 antigen-positive (helper) T cells, averaging 25.2 and 14.7%, respectively. The overall mean T4/T8 ratio was 0.56. T8 antigen-positive T cells were the most numerous cell population outside aggregates and follicles, being distributed almost equally between the acini and the ducts (49%) and the interstitium (51%). Only 16% of T4 antigen-positive cells preferred glands or ducts to the interstitium. B cells, identified with monoclonal antibody BL9, represented only 5.7% of all mononuclear cells present. B cells were exclusively found in the centers of primary and secondary follicles. The majority of the surface immunoglobulin-positive B cells expressed IgM, fewer expressed IgD, and still fewer expressed IgG or IgA. Rare LeuM1+ OKM1+ macrophages were present in the center of B-cell follicles, where rare OKT6+ dendritic cells and activated T cells (IL-2+) were also discovered. These results support the concept that the lacrimal gland belongs to the mucosa-associated lymphoid system.

Lymphocytic subpopulations in the normal human conjunctiva. A monoclonal antibody study

Monoclonal antibodies were used to analyze the lymphocytic subpopulations in frozen tissue sections of normal human conjunctiva (epibulbar, tarsal, and forniceal). The overwhelming majority of lymphocytes were T-cells (Leu1+ and OKT8+). In the epithelium, the predominant cell type was the OKT8+ cytotoxic/suppressor cell, whereas in the substantia propria, helper T-cells (Leu3a/3b+) equalled suppressor T-cells. T-cells outnumbered B-cells 20-fold; the letter cells were detected only in the substantial propria, particularly in the fornices, and not in the epithelium. Plasma cells, as identified by OKT10 staining, were completely absent except in the accessory lacrimal glands of Krause. Langerhans' cells, identified by OKT6 and HLA-DR (la) staining, were observed in the epithelium of all conjunctival regions. Our findings suggest that the reactivity of B-lymphocytes and plasma cells is heavily damped down by T-lymphocytes, thus allying the conjunctiva to other mucosal membranes and the skin as heavily immunoregulated tissues.