Hormonal influence on the secretory immune system of the eye: endocrine interactions in the control of IgA and secretory component levels in tears of rats.

Previous research from our laboratory has demonstrated that androgens regulate the ocular secretory immune system of the rat. The purpose of the present study was to determine whether other hormones might influence this androgen effect. Experiments involved the daily administration of saline or hormones to adult orchiectomized rats, the collection of tears 24 hr after the fourth hormone injection, and the measurement of free secretory component (SC), IgA and total protein levels in tears. Our first aim was to evaluate whether female sex steroids might antagonize androgen action on tear IgA and SC: orchiectomized rats were treated with combinations of saline, testosterone, oestradiol or progesterone. Testosterone induced a significant increase in the tear SC and IgA concentrations, as compared to those of saline-injected controls. This androgen effect was not inhibited by co-treatment with oestradiol or progesterone, nor duplicated by the administration of these hormones alone. Our second aim was to assess whether the absence of certain hormones might alter tear SC and IgA levels, or influence the ocular response to androgen exposure: rats underwent orchiectomies and specific endocrine organ ablations or appropriate sham-surgery. Absence of the pituitary gland, but not the thyroid, adrenal or pineal glands, resulted in a significant decrease in tear SC, IgA and total protein content. In addition, removal of the thyroid or adrenal glands did not prevent the testosterone-associated increase in tear SC and IgA, although thyroidectomy or adrenalectomy did diminish the magnitude of the androgen response. In contrast, hypophysectomy completely blocked the effect of testosterone on both tear SC and IgA. These results indicate that the hypothalamic-pituitary axis may regulate, or mediate, the action of androgens on ocular immunity in the rat

Source of IgA in tears of rats.

The purpose of the present study was to determine whether IgA in rat tears originates from serum and/or local synthesis. To examine the first possibility, we compared the IgA levels in serum and tears of rats with a portacaval anastomosis. This operation induced a chronic and progressive elevation of polymeric IgA concentrations in serum. By 8 weeks after surgery, serum IgA levels in 'portacaval' rats were 20-fold higher than those of sham-operated or intact controls. In contrast, IgA levels in tears of 'portacaval' rats did not increase after surgery, despite the availability of free secretory component (SC) in tears. The lack of correlation between tear and serum IgA concentrations resulted in a significant decrease in the tear IgA/serum IgA ratio after anastomosis surgery. To assess whether tear IgA might be derived from local synthesis, we cultured various ocular tissues from male rats in the presence or absence of cycloheximide, an inhibitor of protein synthesis. Incubation of exorbital (lacrimal) glands resulted in the accumulation of substantial quantities of IgA in the culture medium. This accumulation was significantly reduced by the presence of cycloheximide. In contrast, cycloheximide had no effect on the amounts of IgA in cultures of 'lids', Harder's glands and globes. These results indicate that IgA in rat tears originates from local synthesis and not from serum transfer. Furthermore, our findings suggest that the rat exorbital gland is responsible for the synthesis and secretion of tear IgA

The effect of aging on the secretory immune system of the eye.

The objective of the present study was to examine the influence of aging on the ocular secretory immune system of the eye. Levels of IgA and free secretory component (FSC) were measured in lacrimal glands and/or tears of 0.6, 1.3, 3, 8 and 17-month-old male and female rats. In addition, the FSC output of lacrimal tissue cultured in vitro was evaluated. During the period from 0.6 to 1.3 months of age, the content of tear IgA increased nine- and 13-fold in females and males, respectively. This rise was paralleled by changes in the concentration of tear FSC. Prior to the onset of puberty, FSC could be detected in only 7% of tear samples, whereas after pubertal maturation, tear FSC levels had attained adult concentrations. This tear FSC profile was similar to the age-related pattern of FSC output by lacrimal tissue incubated in vitro. Following puberty, tear IgA content continued to increase in both sexes until adulthood (3 months of age) and then plateaued in females from 8 to 17 months of age. In contrast, tear IgA in males appeared to stabilize from 3 to 8 months and then rose significantly to the highest levels at 17 months of age. This increase in males was also reflected in their lacrimal tissue: IgA content underwent a six-fold elevation from 3 to 17 months. Of interest is that the differential kinetics involved in tear IgA and FSC expression resulted in an age-associated decline in the FSC/IgA ratio from post-puberty to senescence. A striking finding in these studies was the persistence of a sexual dimorphism in the secretory immune system of the eye. After pubertal development, IgA and FSC levels were significantly higher in tears of males, compared to those of females, at all ages tested up to 17 months. These gender- and age-related variations in tear IgA and FSC amounts could not be accounted for by changes in either the volume of, or total protein content in, tears

Comparison fo agglutinin titers for Streptococcus mutans in tears, saliva, and serum.

The agglutinin titers for three Streptococcus mutans serotypes (AHT, BHT, and 10449, representing serotypes a, b, and c, respectively) were measured in the saliva, tears, and serum of 19 human subjects. Naturally occurring S. mutans agglutinins were routinely present in all fluids tested in the absence of overt local stimulation by antigen. The immunoglobulin A nature of this secretory agglutinin activity was suggested by blocking with alpha heavy-chain-specific antiserum and by the demonstration of S. mutans-reactive immunoglobulin A in the saliva and tears by indirect immunofluorescence. This finding is consistent with stimulation and antigen commitment of immunoglobulin A precursor lymphocytes at remote sites and subsequent homing to the lacrimal system. The relationship of anti-AHT agglutinins to anti-10449 agglutinins differed among the body fluids tested. The tears had more agglutinins for strain AHT than for strain 10449, whereas the reverse was true for saliva and serum. A possible explanation is local antigen-driven expansion of AHT-reactive committed lymphocytes in the lacrimal tissues

Hormonal influence on the secretory immune system of the eye: androgen control of secretory component production by the rat exorbital gland.

Androgens are known to regulate the level of secretory component (SC) in tears of male rats. The purpose of the present study was to explore the underlying mechanism of this hormone action by (i) identifying the ocular tissue(s) involved in SC production; and (ii) determining whether androgens increase SC production by this tissue. We also examined whether androgen administration influenced the concentration of SC in tears of female rats. Ocular tissues from adult Sprague-Dawley rats were cultured in the presence or absence of cycloheximide in the incubation medium. Secretory component in the culture media was measured by an RIA which detects primarily free SC. Analysis of media obtained after incubation of exorbital (lacrimal) glands, 'lid' tissues, globes, and Harderian glands revealed that only exorbital glands released substantial amounts of SC. This exorbital gland production of SC, which was significantly greater in tissues from male rats, as compared to those of female rats, was reduced by approximately 50% when cycloheximide was present in the culture medium. To determine whether SC production by exorbital glands was influenced by androgens, orchiectomized glands was influenced by androgens, orchiectomized rats were administered either saline or testosterone (2.0 mg/day for 4 days), and exorbital glands were cultured 24 hr after the last injection. Testosterone treatment in vivo induced a significant, cycloheximide-sensitive increase in SC production in vitro, compared to the glandular SC output of saline-injected controls. It is interesting that similar androgen treatment of ovariectomized females also resulted in elevated tear SC concentrations and enhanced output of SC by their exorbital glands in vitro. These findings indicate that the exorbital gland is primarily responsible for SC production in the rat eye and that androgens may modulate the synthesis of SC in this gland

Biomicroscopy of papillae associated with wearing of soft contact lenses.

We studied the topographical, macrostructural, and fluorescein staining characteristics of papillary changes of the upper tarsal conjunctiva associated with the wearing of hydrophilic (soft) contact lenses. Fifty soft contact lens wearers with elevated conjunctival papillae greater than 0.3 mm in diameter were studied. Topographic characteristics recorded were distribution and number of papillae; macrostructural characteristics recorded were diameter and morphology of papillae. The information collected included age of patient, duration of lens wear, average daily time of wearing lens, presence or absence of itching or mucus, refractive status, and atopic history. Papillae were found in most cases in the conjunctival zone adjacent to the tarsal fold and were never found in the zone adjacent to the eyelid margin without also occurring in the intervening zone. The diameter of the papillae ranged from greater than 0.3 mm to 2.0 mm. The number of papillae per eyelid ranged from 4 to over 100. The apices of the papillae were frequently flattened, and these flattened surfaces frequently stained with fluorescein. The vascular supply of individual papillae was observed to radiate from a vessel occupying the central core of each papilla

Immunoglobulin A antibody levels in human tears, saliva, and serum.

The presence and level of immunoglobulin A (IgA) antibodies to the oral microorganism Streptococcus mutans were determined in human tears, parotid saliva, and serum by a modified, indirect enzyme-linked immunosorbent assay. IgA antibodies were found in the tears of all 15 subjects, although S. mutans is a nonocular bacterium. The IgA antibody levels in tears and saliva were not significantly different. This finding suggests that the level of IgA antibody activity per volume is independent of the naturally occurring site of the antigen, and that local stimulation does not cause a significant difference in the antibody level per volume of secretion between exocrine sites. Much higher levels of IgA antibody were present in serum, suggesting that after oral ingestion of antigen both the systemic and exocrine systems are stimulated. IgG antibodies to S. mutans were also found in human tears, saliva, and serum. No relationship between serum levels and tear and saliva levels was found for either IgA or IgG antibodies. Thus the antibodies in tears and saliva did not appear to have leaked from serum. We conclude that there may be remote regulation of both the ocular and the parotid IgA and IgG antibody systems

Ocular anaphylaxis: induction by local injection of antigen.

A model of local ocular anaphylaxis has been developed in the rat. Erythema, oedema, and enhanced retention of radioiodinated rat serum albumin ([125I]-RSA) were noted in ocular adnexal tissues of immunized rats within 5 min of injection of antigen; these changes reached a maximum 15 min after antigen injection. Erythema, oedema, and retention of [125I]-RSA subsided to baseline levels 1--6 hr after challenge. A significant increase in weight of ocular adnexal tissues was seen within 15 min after challenge. The weight increase reached a maximum at 45 min and persisted through 6 hr. Weight approached baseline values by 24 hr. Although antigen was injected into the ocular adnexa and not directly into the globe, the globes of the antigen-injected eyes of immunized rats underwent anaphylaxis, possibly because of absorption of antigen through the sclera. In addition, the adnexa and globes of the contralateral eyes, which did not receive antigen, also underwent anaphylactic changes. These changes were not as marked as those observed in the antigen-injected tissues, but followed the same time-course of development. We conclude that anaphylaxis can be locally induced in ocular tissues, that the onset of anaphylaxis is within minutes, and the effects last for at least 24 hr

Sequence of mast-cell changes in ocular anaphylaxis.

Ocular anaphylaxis was produced in rats by the injection of egg albumin into ocular adnexal tissues of immunized animals. Mast cells in the tip of the eyelid from normal, antigen-injected control and antigen-injected immunized rats were examined at 1/2, 1, 6 and 24 hr. The number of cells and their morphology was determined. All three groups had the same number of mast cells at all time intervals. Extensive mast-cell degranulation was observed at 1/2 and 1 hr in lid tips of immunized, antigen-challenged rats. By 24 hr, the mast cells appeared to have 'healed' and regranulated, although it was possible to distinguish these cells from mast cells of normal animals. We conclude that under certain conditions, mast cells participating in ocular anaphylaxis are not destroyed but survive and regenerate granules within the first 24 hr