Secretory immunoglobulin A in oral and respiratory passages in man

μ-chain-deficient mice possess B-1 cells and produce IgG and IgE, but not IgA, following systemic sensitization and inhalational challenge in a fungal asthma model

Allergic bronchopulmonary aspergillosis is often difficult to treat and results in morbidity associated with chronic airway changes. This study assessed the requirement for B cells and their products in the allergic pulmonary phenotype in a murine model of fungal allergic asthma that mimics allergic bronchopulmonary aspergillosis. C57BL/6 and μMT mice (assumed to lack peripheral B cells) were sensitized with Aspergillus fumigatus extract and challenged with two inhalation exposures of live conidia to induce airway disease. Airway hyperresponsiveness after methacholine challenge, peribronchovascular inflammation, goblet cell metaplasia, and fibrotic remodeling of the airways was similar between μMT mice and their wild-type counterparts (C57BL/6). Surprisingly, even in the absence of the μ-chain, these μMT mice produced IgE and IgG Abs, although the Abs induced did not have specificity for A. fumigatus Ags. In contrast, IgA was not detected in either the lavage fluid or serum of μMT mice that had been exposed to A. fumigatus. Our findings also reveal the existence of CD19(+)CD9(+)IgD(+) B-1 cells in the lungs of the μMT animals. These data show the μMT mice to have a developmental pathway independent of the canonical μ-chain route that allows for their survival upon antigenic challenge with A. fumigatus conidia, although this pathway does not seem to allow for the normal development of Ag-specific repertoires. Additionally, this study shows that IgA is not required for either clearance or containment of A. fumigatus in the murine lung, as fungal outgrowth was not observed in the μMT animals after multiple inhalation exposures to live conidia.

Intranasal immunization with Naegleria fowleri lysates and Cry1Ac induces metaplasia in the olfactory epithelium and increases IgA secretion

According to previous reports, intranasal administration of the Cry1Ac protein alone or with amoebic lysates increases protection against Naegleria fowleri meningoencephalitis in mice, apparently by eliciting IgA responses in the nasal mucosa. In the current study, we performed an immunohistochemical analysis of IgA in the nasal mucosa of mice immunized intranasally with Cry1Ac, and amoebic lysates or a combination of both. The animals were sacrificed 24 h after the last immunization or after an intranasal lethal challenge with N. fowleri. Our results indicate that all of the intranasal immunizations provoked an increase in areas with metaplasia in the olfactory epithelium, allowing for secretion of IgA. As a result, IgA antibodies were found interacting with trophozoites in the nasal lumen, and there was a marked increase of IgA in the metaplasic epithelium. On the other hand in nonimmunized mice trophozoites were observed invading the nasal mucosa, which was not the case for immunized mice. Our results suggest that intranasal immunization provokes cellular changes in the olfactory epithelium, leading to greater protection against N. fowleri that is probably caused by an increased secretion of IgA. The increased IgA response induced in the nasal mucosa by immunization probably impedes both amoebic adhesion and subsequent invasion of the parasite to the nasal epithelium.

Epstein-Barr virus infection of Langerhans cell precursors as a mechanism of oral epithelial entry, persistence, and reactivation

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus associated with many malignant and nonmalignant human diseases. Life-long latent EBV persistence occurs in blood-borne B lymphocytes, while EBV intermittently productively replicates in mucosal epithelia. Although several models have previously been proposed, the mechanism of EBV transition between these two reservoirs of infection has not been determined. In this study, we present the first evidence demonstrating that EBV latently infects a unique subset of blood-borne mononuclear cells that are direct precursors to Langerhans cells and that EBV both latently and productively infects oral epithelium-resident cells that are likely Langerhans cells. These data form the basis of a proposed new model of EBV transition from blood to oral epithelium in which EBV-infected Langerhans cell precursors serve to transport EBV to the oral epithelium as they migrate and differentiate into oral Langerhans cells. This new model contributes fresh insight into the natural history of EBV infection and the pathogenesis of EBV-associated epithelial disease.

A survey of the pattern of glandular distribution in the larynges of human infants

We studied the development of glandular structures and the pattern of distribution of serous and mucous-type glands in the larynges of 77 human infants obtained at autopsy. The subglottic larynx was subjected to quantitative and qualitative analysis, using an image binarization procedure. The areas of mucosa and inner space of the subglottic larynx tended to increase with age. The area occupied by the glands differed considerably in younger infants and the areas of total glands and serous-type glands increased with age. There was no correlation between the area of the mucous glands and age. These findings indicate that local immune function of the secretory glandular system in the larynx of human infants increases with advancing age.

Sheep red blood cell instillation at palatine tonsil effectively induces specific IgA class antibody in saliva in rabbits

We have shown that the palatine tonsil effectively incorporates exogenous foreign substances instilled at its surface. It is not clear whether antigen-specific IgA can be induced by the instillation. Sheep red blood cells (SRBC) were instilled at the palatine tonsil every three days as the antigen, and the agglutination titer of specific IgA in saliva was examined. Nasal or intragastric administration, which have been shown to induce specific antibody in saliva, were done as control experiments. Anti-SRBC antibody in saliva from the tonsillar instillation group was detected in the second week, and the agglutination titer reached a maximum in the 6th week after instillation. The maximum titers in the tonsillar instillation group and nasal administration group were 16 (P < 0.01, n = 7) and 4 times (P < 0.01, n = 7) higher, respectively, than that in the intragastric administration group. In the tonsillar instillation group, the number of specific antibody- producing cells per 10(5) lymphocytes was the highest in the parotid glands compared with the lymphoid tissues such as the retropharyngeal lymph nodes, nasal mucosa, mesenteric lymph nodes, Peyer's patches, cervical lymph nodes, palatine tonsil and spleen. In the nasal administration group, the number of lymphocytes was the highest in the nasal mucosa. The results indicate that tonsillar instillation was more effective than nasal administration in inducing specific iIgA in saliva.

The potential role of the ovine pharyngeal tonsil in respiratory tract immunity: a scanning and transmission electron microscopy study of its epithelium

The mucosal epithelium of the pharyngeal tonsil was studied in 10 conventionally raised sheep by scanning and transmission electron microscopy. The surface of the tonsil was covered by two types of topographically and ultrastructurally distinct epithelium. The epithelium overlying the lymphoid follicle region (follicle-associated epithelium) was compressed by adjacent ciliated epithelium and consisted of predominantly non-ciliated cells of varying height. The majority of these cells possessed microvilli or microfolds of varying number, height and density on their surface. Small numbers of squamous cells and, occasionally, intermediate cells were also present in these areas. Ultrastructurally, the microvillous cells showed features similar to M cells which occur in other mucosal sites. They contained cytoplasmic vesicles and vacuoles and formed intercellular digital junctions. Between these cells was a heavy infiltration of lymphoid cells. Focal disintegration of the mucosal epithelium was occasionally seen. The epithelium covering non-follicle areas consisted of mainly ciliated cells interspersed with some goblet cells and squamous cells, morphologically resembling those elsewhere in the respiratory tract. These findings have provided evidence which confirms that the ovine pharyngeal tonsil is part of the respiratory tract-associated lymphoid tissue.

Serum immunoglobulins in patients with chronic tonsillitis

Serum immunoglobulin (IgG, IgA and IgM) levels were determined in patients with chronic tonsillitis before and one month after tonsillectomy. The preoperative levels of serum IgG, IgA and IgM were significantly higher when compared with the controls. The increase may be due to repeated antigenic stimulation. The post-operative levels for the three immunoglobulins were decreased; however, a significant reduction was observed for IgG only where the mean value was comparable with the control group. The data confirm that tonsillectomy does not disturb the humoral immune system of the body.

Induction and delivery of mucosal immune responses

The oral cavity is relatively deficient in lymphoid tissue capable of directing the inductive and effector events required for effective mucosal IgA responses to local antigen. Recent evidence regarding a common mucosal immune system has raised new possibilities in immunization of mucosal surfaces. This review describes the role of the intestine in contributing to responses at distant mucosal sites and in particular emphasizes the immune potential of the intestine in determining the success of immunization strategies to control dental caries.

Serum immunoglobulins in patients with chronic tonsillitis

In this work, the serum immunoglobulin (IgG, IgA, IgM and IgD) levels were determined in ten patients with chronic tonsillitis. The serum immunoglobulins were estimated before and two months after tonsillectomy, using the radial immuno-diffusion method. Ten normal individuals with intact tonsils were chosen as a control group. The patients had elevated serum levels of IgG and IgA. These high levels may be due to repeated antigenic stimulation. The IgM and IgD were not significantly higher than in the normal controls. The serum IgG level did decrease significantly following tonsillectomy; the other three immunoglobulins were reduced, but insignificantly. The fall in immunoglobulins may be due to a reduction in the antigenic load, to the removal of immunoglobulin-producing tissue, or to alteration in the oropharyngeal pathogenic bacteria. Tonsillectomy does not seem to compromise immunological integrity or the immunoglobulin-producting apparatus. Estimations of the serum immunoglobulin, or simply of IgA, may help us to select those candidates for adeno-tonsillectomy who will have a good prognosis, or at least to exclude those with an underlying sub-clinical immunodeficiency disease.

Immunofluorescent study on middle ear mucosa

To clarify the developmental course of the immunological defense system in the middle ear, immunoglobulin-forming cells of different classes and secretory proteins, such as secretory component (SC) and lactoferrin (Lf), were investigated in the middle ear mucosa of 20 developing and 5 normal adult guinea pigs by use of direct immunofluorescence technique. Changes in the middle ear mucosa were also observed after antigenic challenges directly to the tympanic cavity of 6 developing and 39 adult guinea pigs. IgA- and IgM-forming cells began to appear in the tubal mucosa at the seventh postnatal day, while it was scarcely possible to find IgG1- and IgG2-forming cells in developing guinea pigs. Immunoglobulin-forming cells of all classes increased in the middle ear mucosa after the antigenic stimuli. The injection of antigens to the tympanic cavity of developing animals induced the most striking accumulation of immunoglobulin-forming cells in the middle ear mucosa. Results of this study showed that local synthesis of IgA, as well as other classes, is latent in the middle ear, that the middle ear of immature animals is vulnerable to antigenic stimuli, and that the middle ear of developing animals possesses potential immune responsiveness.

Immunologically induced changes in the tonsillar crypt epithelium

The normal gross and microscopic anatomy of the palatine tonsil of the rabbit was observed, and following the direct injection of antigenic substance, structural changes were noted in the crypt epithelium. A cold light laryngoscope tube was used to inject ovalbumin or bovine serum albumin, plus Freund's complete adjuvant, into the subepithelial lymphatic tissue. Five weeks later subcutaneous challenge injections of the same protein produced increased numbers and proportions of infiltrated small lymphocytes and medium-sized lymphocytes containing a highly organized granular endoplasmic reticulum. These cells occupied wide intercellular passageways. Epithelial plasma membranes that faced these passageways remained smooth, but other surfaces of the same epithelial cells acquired vastly increased numbers of microvilli. The surfaces of other epithelial cells that faced each other also showed microvilli. These microvilli faced expanded interfacial canals. Increased numbers of small lymphocytes were observed emigrating through postcapillary venules immediately beneath the epithelium. The microvilli and other fine structures of tonsillar crypt epithelial cells are compared with similar structures of epithelial cells of the thymus. The experimentally induced increase in microvilli suggests the possibility that tonsillar crypt epithelial cells make a secretory contribution to local immune reactions.

Secretory IgA and antibody activities in middle ear effusions

Secretory IgA (SIgA) was isolated from pooled middle ear effusions (MEE) and its antigenicity and subunit structure were found to be identical to those of SIgA in saliva, nasal secretion and colostrum. The calculated percentage of SIgA in the total IgA of effusions was approximately 11%. Although the SIgA antibodies against streptolysin and staphylolysin were very low when compared to that of IgG class in effusion, this finding confirmed that MEE is at least partially a result of local immunologic reactions. The IgE concentration did not become elevated in both the MEE and serum obtained from patients with otitis media with effusion. Specific reaginic activity against mites was found in 5 of 56 (8.9%) MEE. Our findings would not suggest the significant role of atopic allergy in the formation of MEE.