Immunoglobulin formation and function in different tissues

Laboratory findings in tear fluid analysis

The tear film, composed of the lipid, aqueous and mucin layers, has many functions including defending the ocular surface. The tear film covering the ocular surface presents a mechanical and antimicrobial barrier and ensures an optical refractive surface. The lipid component originates from the meibomian glands of the tarsus and forms the superficial layer of the tear film. The aqueous component contains electrolytes, water, and a large variety of proteins, peptides and glycoproteins, and is primarily secreted by the lacrimal gland. Mucins are glycoproteins expressed by epithelial tissues of mucous surfaces. They protect tissues by functioning as antioxidants, providing lubrication, and inhibiting bacterial adherence. Quantitatively and qualitatively, its composition must be maintained within the fairly narrow limits to maintain a healthy and functional visual system. Abnormalities of the tear film, affecting the constituents or the volume, can rapidly result in serious dysfunction of the eyelids and conjunctiva and ultimately affect the transparency of the cornea. Many ocular surface tests have been developed for the clinical diagnosis of dry eye syndromes. This paper provides an overview on laboratory methods for the analysis of the tear film. Understanding the components of the tear film will aid in the treatment of dry eye syndromes and the ocular surface diseases.

Is there a role for a mucosal influenza vaccine in the elderly?

Influenza infection is an acute respiratory disease with a high morbidity and significant mortality, particularly among the elderly and individuals with chronic diseases. The majority of countries now recommend annual influenza vaccination for all people aged 65 years or older, and for those with high risk conditions. Most commercially available influenza vaccines are administered systemically and while these are effective in children and young adults, efficacy levels in elderly individuals have been reported to be much lower. Mucosal vaccines may offer an improved vaccine strategy for protection of the elderly. As the influenza virus causes a respiratory infection, it is potentially more beneficial to administer a vaccine that will boost protection in the mucosal surfaces of the upper and lower respiratory tract. Mucosal influenza vaccines are aimed at stimulating protective immunity in the respiratory tract via oral or intranasal immunisation. This review examines our present knowledge of mucosal immunity and current strategies for mucosal vaccination. It also stresses that the use of serum antibody levels as a 'surrogate marker' for protection against influenza is potentially misleading; serum antibody, for example, may be a quite inappropriate marker to assess a mucosal vaccine. This marker does not reflect other immune responses to vaccination that are crucial for protection.

Biliary secretory IgA levels in rats with protein-calorie malnutrition

Malnutrition is a recognized cause of failure of host defense mechanisms. In the past 5 years, it has been demonstrated that the gut, long known to have significant morphologic changes with protein calorie malnutrition (PCM), is an immune organ affected by malnutrition. To assess the role of biliary immunoglobulin A (S-IgA), part of the barrier to bacterial invasion from the gastrointestinal tract, the following study was performed. Seventy-eight Fisher female inbred rats weighing 110-130 g were randomly separated into two groups. The control rats were fed standard rat chow. The experimental rats were fed a 2% agar protein depletion (PCM) diet (USP XV). The biliary tract of the rat was cannulated with Silastic tubing and bile flow and rat secretory immunoglobulin A (S-IgA) was sampled at intervals. S-IgA was measured by the Elisa method. Total bile protein was measured by micro-Kjeldahl. Bile was collected from the rats on day 0, 7, 14, 21, 29, 36, 42, and 49. During the study, the weight of rats fed the PCM diet decreased from 127.4 +/- 14.5 g at day 0 to 83 +/- 2.6 g on day 37. Control rats gained weight from 124.4 +/- 14.5 g at day 0 to 153.6 +/- 3.8 g at day 37. Total biliary protein at day 0 was 2.52 +/- .05 mg/ml and at day 36 was 2.51 +/- 11 mg/ml for PCM rats and 2.57 +/- 10 mg/ml for control rats. Normal rats and control rats both had an initial increase of S-IgA from 2.74 +/- 73 mg/ml on day 0 to 5.75 +/- 1.75 mg/ml on day 37. Both PCM and control rats demonstrated an increase in S-IgA levels despite significant loss of weight in the experimental group. Similarly, total biliary protein was not decreased in either group. The results suggest that gut immune system is preserved despite significant protein calorie malnutrition.

Antiviral antibody-producing cells in parenchymatous organs during persistent virus infection

In mice persistently infected with lymphocytic choriomeningitis virus (LCMV), the parenchymatous organs contain infiltrates of mononuclear cells, the sizes and numbers of which vary between strains and become more numerous and extensive when the animals grow older. Histologically, these were found to possess a tissue-like structure, and by use of immunohistologic procedures they were shown to contain plasma cells secreting IgM and IgG. Cells of kidneys, livers, brains, and spleens of LCMV carrier mice were dispersed by digestion with trypsin, leukocytes were separated by density gradient centrifugation, and numbers of cells producing antibodies against LCMV were determined by use of a solid-phase immunoenzymatic technique. In all these organs, cells producing LCMV-specific IgM and IgG antibodies were demonstrated, the latter more numerous than the former. Their numbers correlated with numbers and extent of the lymphoid cell infiltrates. The blood of the same mice was essentially free of antiviral antibody-forming cell. The proportion of cells producing LCMV-specific antibodies to all cells producing Ig of any specificity varied between organs, being lowest in spleen, intermediate in liver and kidney, and highest in the brain, where in individual mice up to 90% of all active cells produced virus-specific antibodies. The LCMV carrier mouse should prove to be a useful animal model to investigate antibody production in parenchymatous organs during persistent virus infections.

Antigen processing and uptake from the intestinal tract

We have attempted, in this discussion, to summarize the processes and evidence for absorption of antigenic macromolecules in both animals and humans, comparing the infant to the adult. The mature gut retains the capacity to absorb macromolecules by an energy-dependent pinocytotic mechanism similar to that described for the transport of immunoglobulins and other enteric antigens in certain mammalian species in the neonatal state. The vast majority of adults show no ill effects as a result of this physiologic phenomenon. However, when increased (pathologic) quantities of antigenic macro-molecules gain access to the body because of a derangement in the intraluminal digestive process, or because of a defect in the mucosal barrier, both of which are present in the immature intestine, macromolecular absorption may be altered and result in either local intestinal or systemic disorders.

Nasal secretory IgA circadian rhythm: a single-dose suppression test

The existence of a clear circadian rhythm in the local secretion of nasal IgA is well-known phenomenon which is confirmed in the present research. Since the temporal pattern of secretory IgA (SIgA) strictly parallels the ACTH-cortisol cycle, a dependence was hypothesized in previous research, but the suppression of adrenal rhythm by means of massive doses of exogenous corticosteroids showed no influence on the SIgA cycle. In the present research a more sophisticated method of corticoid-incretion suppression was used; the single-dose suppression test with dexamethasone, which influences only the impulsive phase of the rhythm. In this case too, however, no influence was demonstrated on nasal SIgA secretion.

Clinical immunology in ophthalmology. The 1975 Bedell lecture

Immunology has played a recognizable role in ophthalmology for many years. The old immunology concerned itself with antibodies, skin tests, complement, agglutinins, precipitants, and lysins. The old immunology was responsible for the remarkable development of vaccines, vaccinations, antisera, and the prophylactic use of toxins. The new immunology cannot display such achievements as yet. However, continued study in this area could lead to significant improvements in diagnosis, prognosis, and the development of effective immunoregulants in inflammatory and neoplastic disease.

The effect of disodium cromoglycate (DSCG) on the levels of albumin and the immunoglobulins IgA, IgG, IgM and IgE in sputum

Sputum samples from control subjects with cardiac disease and from patients with asthma were assayed for albumin content and immunoglobulins IgA, IgG, IgM and IgE. The asthmatics were divided into three groups: one group had received disodium cromoglycate (DSCG) for at least 48 hr prior to sampling, another group was sampled daily after commencing DSCG therapy and the third group were not taking DSCG. Albumin and immunoglobulins accounted for approximately 8% of the total sputum proteins in each of the four groups of subjects. There was no significant difference in the mean sputum levels of albumin or the immunoglobulins, when expressed as a percentage of total sputum proteins, between the subjects in each group. However, the ratios of IgA/albumin and IgA/IgG in the asthmatic group receiving DSCG were significantly lower than the corresponding ratios in sputa from both asthmatics and control subjects with cardiac disease. The sputum IgE levels tended to be higher in the asthmatics than in the control group, but DSCG therapy had little effect upon sputum IgE levels.

Local antibody response to experimental poliovirus infection in the central nervous system of rhesus monkeys

By employing the techniques of immunofluorescence and radioimmunodiffusion using (32)P-labeled poliovirus as the antigen, the immunoglobulin response to poliovirus in serum, nasopharynx, spinal fluid, and in different segments of the central nervous system (CNS) was studied after intramuscular, oral, intranasal, and intrathalamic administration of inactivated (Salk), live attenuated (Sabin), or live virulent (Mahoney) type I poliovirus. Spinal fluid gammaG antibody was detected after immunization with Sabin or Mahoney virus and intramuscular administration of Salk vaccine. The response in the CNS was characterized by the appearance of gammaG antibody after oral or intrathalamic administration of Mahoney virus and rarely after intrathalamic inoculation of Sabin vaccine. The antibody activity in CNS was limited to the areas of poliovirus replication. Intrathalamic immunization with Mahoney virus resulted in local gammaG antibody production in the CNS in the absence of any detectable response in serum. Discrete foci of gammaG-containing cells were observed in those areas of CNS which contained poliovirus antibody. No immunoglobulin-containing cells or poliovirus antibody was seen in the CNS of monkeys immunized with intramuscularly or orally administered Sabin or Salk vaccine and in sham-immunized control monkeys. It is suggested that the CNS, when stimulated locally with a potent replicating viral antigen, may manifest a specific local antibody response, which is independent of the response in serum.

Dental caries: prospects for prevention

Combined utilization of measures now available or imminent could reduce caries of the crowns of the teeth to the point of negligibility as a public health problem, if public desire were great enough to motivate changes in some of our habits (64). Universal optimum application of fluoride and substitution of starchy foods for sugary ones (or even simply judicious consumption of sugar) would alone do most of the job. Sealing of susceptible occlusal areas with adhesive polymers promises to protect the sites where fluoride evidently cannot be maximally effective. It seems unlikely that any single measure will be found sufficient to control this multifactorial disease. Consequently, we must continue the search for new means to increase the caries resistance of teeth, to reduce the cariogenicity of foodstuffs, and to check the deleterious activities of cariogenic bacteria. Anticaries food additives and antibacterial agents for intraoral use seem to be approaching practicability. Past performance warrants expectation that ongoing fundamental investigations will produce leads for future development and application.

The enterocyte in coeliac disease

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In vitro and in vivo studies of streptomycin-dependent cholera vibrios

Streptomycin-dependent cholera vibrio strains were derived from Inaba, Ogawa, and NAG vibrios by the method of Mel. These phenotypes grew more slowly and attacked fermentable substances after a longer period of time than the streptomycin-sensitive parent strains. Rabbits injected with streptomycin-sensitive strains and their streptomycin-dependent forms showed homologous agglutinin production. Patas monkeys fed with 10(9) streptomycin-dependent strains shed them for 1 to 2 days without ill effect, whereas the same number of streptomycin-independent organisms caused disease. The possibility of the application of multiple doses of streptomycin-dependent organisms in oral immunization against cholera was considered.

Immunosuppression and experimental virus infection of the nervous system

This chapter describes the current views of the pathogenesis of virus infections of the nervous system, with particular attention to certain aspects of virus-host interactions. Following invasion of the central nervous system, infection can follow a variety of patterns, as to number and distribution of neuronal and non-neuronal cells involved. There is a corresponding diversity in the pathological lesions of the central nervous system (CNS) produced by acute virus infection. Infection can be pictured as a race between virus and host defenses, where many factors, acting through different mechanisms, can influence the outcome. Outcome is always determined by multiple virus and host variables, although single variables can be independently studied under experimentally controlled conditions in the laboratory. The chapter demonstrates that in many virus-host combinations, the immune response plays an important role in recovery from primary infections. It mentions that an immunopathological process mediates the disease which follows certain CNS virus infections.