Immunoglobulin-containing cells in normal human labial salivary glands

The distribution of immunoglobulin-containing cells within 8 normal human labial salivary glands was studied using an immunoperoxidase technique. Cell counts revealed that IgA-containing cells pre-dominated in all specimens and that the mean percentage class ratios for IgG:IgA:IgM:IgD cells were 4:92:3:1. IgE cells were rare and only detected in one gland. The density of IgA cells (191 cells/mm2 of labial gland section) was greater than those previously reported for the parotid and submandibular glands. These results support the view that minor salivary glands play an important role in the synthesis and secretion of salivary antibody.     

Ontogenesis of the secretory immune system and innate defence factors in human parotid glands

Immunoglobulin-producing cells and epithelial expression of secretory component (SC), amylase, lysozyme (Ly) and lactoferrin (Lf) were studied by immunohistochemistry to obtain information about the development of mucosal immunity. Tissue specimens were obtained from 20 fetal and 40 postnatal parotid glands. (1) Fetal specimens. Occasional IgM- and IgA- but no IgD-, IgG- or IgE- producing cells were seen (ratios, IgM:IgA:IgD:IgG:IgE approximately 4:1:0:0:0). The IgAl subclass dominated (median 90%, range 50-95%) and these cells were mostly J-chain-positive (median 97%, range 94-98%). Only few IgA2-producing cells were seen (median 10%, range 5-50%) and they were also mostly J-chain-positive (median 99%, range 98-100%). Amylase, Ly and Lf were most prominent in early fetal life, while only small amounts of SC were present. (2) Postnatal specimens. Secretory component increased markedly along with a growing number of IgA- and IgD-producing cells (IgA:IgM:IgD:IgG:IgE approximately 4:2:1:1:0). The IgAl subclass remained predominant (median 65%, range 50-90%) although the proportion of IgA2-positive cells tended to be raised (median 35%, range 10-50%). Most IgAl (median 97%, range 67-100%) and IgA2 (median 94%, range 75-100%) cells were J-chain-positive. These features probably reflected local activation of the immune system in response to environmental factors. The amount of amylase, Ly and Lf decreased shortly after delivery, perhaps because the cellular stores were emptied by postnatal increase in secretory activity.     

The clinical condition of IgA-deficient patients is related to the proportion of IgD- and IgM-producing cells in their nasal mucosa

Nasal biopsy specimens from 15 adult patients with selective IgA deficiency but normal IgG-subclass levels were examined by immunohistochemistry for the presence of immunocytes producing various Ig isotypes. The mucosal samples were completely IgA-deficient except in two cases where 0.9% and 8.4% IgA cells were found, respectively (normal, 69.8%). Numerous IgG- (mainly IgG1-) producing cells were present in 10 samples; in five of these there were additional IgM- but virtually no IgD-producing cells, whereas in the other five a marked dominance of the IgD over the IgM isotype was seen. The latter category of patients had more upper airways infections (recurrent acute rhinosinusitis, otitis media, and tonsillitis) than the former, who had no recurrent upper respiratory tract infections except one patient with recurrent acute rhinosinusitis. The five remaining samples, which contained very few Ig-producing cells, were derived from patients with even more frequent infections than those showing IgD predominance. Our results indicate that IgM acts as a compensatory secretory Ig in the upper respiratory tract of some IgA-deficient subjects. However, immunoregulatory events favouring local IgD responses apparently do not support mucosal defence satisfactorily, either because local production of IgM is hampered or because IgD (which is not a secretory Ig) blocks complement-dependent reactions mediated by IgG and IgM antibodies within the mucosa.     

Secretory immune responses in ageing rats. II. Phenotype distribution of lymphocytes in secretory and lymphoid tissues.

The distribution of lymphocyte phenotypes was examined in various tissues from weanling (21-35 days), adult (3-4 months), mid-life (10-12 months) and senescent (18-20 months) rats. Lymphoid tissues included peripheral blood, spleen, cervical, mesenteric and inguinal lymph nodes. Tissues associated with secretory immune responses were also examined, including submandibular and parotid salivary glands, extraorbital lacrimal glands and Peyer's patches. IgA, IgG and IgM B cells were determined by surface Ig staining. Total T cells (W3/13), T helper/inducer (Th) (W3/25), T suppressor/cytotoxic (Ts) (OX8) and immature T cells (Thy 1.1; OX7) were also evaluated. IgG B cells were significantly decreased in lymphoid tissues from the senescent rats, while the weanling group exhibited decreased levels of all three B-cell isotypes compared to adult animals. IgA B cells were significantly decreased in the secretory tissues of the senescent rats, while IgM B cells were increased in both the weanling and senescent groups. Total T-cell percentages were unaffected by ageing in any of the tissues. The only consistent alteration in the lymphoid tissues was a decrease in Thy 1.1-positive cells in the older groups compared to the weanling group. A decreased Th cell percentage was demonstrated in the salivary and lacrimal glands of the weanling and senescent groups. Decreases in Th/Ts ratios, as well as decreased numbers of plasma cell precursors in the secretory tissues of the aged rats, suggests that alterations in normal secretory immune responses may be expected to accompany the ageing process.     

鼻咽癌IMRT前后唾液腺功能变化及与受照剂量的关系

目的:探讨鼻咽癌患者调强放射治疗（IMRT）前后唾液腺的功能变化及与受照剂量的关系。方法:选取广西医科大学第一附属医院接受IMRT初治鼻咽癌患者30例为研究对象,在放疗前、放疗后3个月采用99mTcO4-SPECT唾液腺动态显像测定腮腺、颌下腺的时间-放射性曲线（TAC）、最大浓聚率（MAR）和酸刺激最大分泌率（MSR）,研究唾液腺的功能变化及与受照剂量的关系。结果:放疗后3个月出现1~2级口干症状,腮腺、颌下腺TAC曲线主要表现为轻中度受损,口干程度、TAC曲线与唾液腺受照剂量正相关。放疗后3个月较放疗前腮腺MAR、MSR和颌下腺MSR明显减低（P<0.05）,而颌下腺的MAR无减低（P>0.05）,但两组唾液腺的MAR、MSR对比差异无统计学意义（P>0.05）,两组唾液腺照射剂量均合理。结论:鼻咽癌患者IMRT后出现唾液腺摄取和排泄功能轻中度受损,引起1~2级口干,IMRT能够将唾液腺的受照射剂量控制在合理范围内。     

Local IgA and IgM rheumatoid factor production in autoimmune MRL/lpr mice.

Spontaneous local immunoglobulin (IgA, IgG, IgM) as well as IgA and IgM rheumatoid factor (RF) production in salivary glands, lymph nodes, and spleen was analyzed at various ages in autoimmune MRL/Mp-lpr/lpr (MRL/lpr) mice by using an ELISPOT assay. The longitudinal design of the study permitted correlations with severity of disease in salivary glands (sialadenitis). Local production of immunoglobulins in salivary glands and lymph nodes occurred with a pattern of IgG much greater than IgM greater than IgA. This isotype pattern differed from that simultaneously observed in spleen where IgG did not predominate to the same extent. Moreover, the spleen was the major site of IgM production. Rheumatoid factors constituted a significant fraction of local IgA and IgM in involved salivary glands. The pattern of IgA RF isotype expression in salivary glands contrasted with that observed in spleen. While the number of IgA and IgG secreting cells increase at an early age, the peak of RF production in salivary glands occurs in older mice. Furthermore, the level of immunoglobulin secretion was positively correlated with disease severity in salivary glands. The results suggest that local RF production is a secondary event in salivary gland inflammation in MRL/1pr mice rather than an initiating factor in this process.     

颌下腺及腮腺超声检查对原发性干燥综合征的诊断价值

目的 探讨颌下腺及腮腺超声检查对原发性干燥综合征（pSS）的诊断价值。方法 回顾性研究。选取2017年1月—2020年12月南通大学附属江阴医院确诊pSS患者88例为pSS组,其中男3例、女85例,年龄27~78（53±11）岁。纳入同期有口干或眼干临床表现的非pSS患者49例为对照组,其中男2例、女47例,年龄21~79（55 ±13）岁。患者均行双侧颌下腺及腮腺超声检查,并据二维灰阶图采用0~4分法进行评分。观察指标：（1）比较2组患者年龄、性别、口眼干燥等临床基线资料;（2）记录2组患者的颌下腺和腮腺超声评分,分别绘制颌下腺、腮腺、颌下腺联合腮腺超声评分诊断pSS的受试者操作特征（ROC）曲线,据约登指数确定超声评分的最佳诊断阈值,以及相应的灵敏度、特异度,比较颌下腺、腮腺、颌下腺联合腮腺超声评分的曲线下面积（AUC）;（3）比较pSS组患者双侧颌下腺和腮腺的超声评分,分析颌下腺与腮腺超声评分的相关性。结果 （1）88例pSS组及49例对照组患者的年龄、性别及口眼干燥表现差异均无统计学意义（P值均>0.05）;（2）ROC曲线显示,颌下腺、腮腺、颌下腺联合腮腺超声评分诊断pSS的约登指数分别为0.669、0.650、0.628,3种方式的最佳诊断阈值均为2分;3种方式诊断pSS的灵敏度分别为95.5%、77.3%、95.5%,特异度分别为71.4%、87.8%、67.3%,AUC[95%可信区间（CI）]分别为0.908（0.856~0.959）、0.845（0.780~0.910）及0.900（0.847~0.953）。其中颌下腺及颌下腺联合腮腺的AUC均高于腮腺,差异均有统计学意义（Z=2.43、2.31,P=0.015、0.021）,而颌下腺与颌下腺联合腮腺的AUC差异无统计学意义（Z=1.36,P=0.175）。（3）pSS组患者中,颌下腺超声评分为3（2,3）分,高于腮腺的2（2,3）分（Z=-8.22,P<0.001）;颌下腺与腮腺的超声评分呈正相关（r_s=0.79,P<0.001）。结论 颌下腺及腮腺超声对pSS均具有较高的临床诊断价值,颌下腺超声可能较腮腺更具优势。     

The expression and localization of osteopontin in the mouse major salivary glands

The present study investigated the expression and distribution of osteopontin in the mouse major salivary glands. The level of osteopontin expression in the mouse submandibular gland was higher (12.7-fold) than that in parotid and sublingual glands at the mRNA level. By Western blot analysis, intense positive bands were seen at the predicted molecular mass (about 55 kDa) in all the major salivary glands, while an approximately 30 kDa band of osteopontin was detected only in the submandibular gland. Indirect immunofluorescent and immuno-electron microscopy analyses demonstrated the localization of osteopontin in the luminal (apical) membranes of acinar cells in all the salivary glands. Osteopontin was also localized at the lumen of acini in the submandibular gland. These results suggest that the expression of osteopontin in the submandibular gland is different from that in the parotid and sublingual glands and that osteopontin may be degraded in the mouse submandibular gland.     

Distribution of immunoglobulins in equine tissues by indirect immunofluorescence

Monospecific rabbit antisera directed against the heavy chains of horse IgG_a, IgG_b, IgG_c, IgA, IgB, IgG(T) and IgM were employed as reagents in the indirect immunofluorescent staining of horse tissues. Cells showing cytoplasmic staining for specific equine immunoglobulin heavy chain types could be identified and their distribution in horse parotid and submaxillary glands was compared with that obtained for the parotid and mesenteric lymph nodes as well as duodenum.Immunofluorescent staining of parotid and mesenteric lymph node sections revealed cells showing cytoplasmic fluorescence for IgG_a, IgG_b, IgG_c and IgM among lymphoid cells comprising the core of germinal centres and medullary cords. IgA and IgG(T) staining was localized in cells predominantly situated in the cortex and around the periphery of germinal centres.Cells showing specific cytoplasmic staining for IgB were not found in sections of salivary glands or duodenum. Rare, isolated, single cells containing IgB immunoglobulin were encountered in cortical areas of parotid and mesenteric lymph nodes.Salivary glands stained for IgA showed localization of IgA immunoglobulin in individual cells of the acinar and ductular epithelium as well as in the cytoplasm of interstitial plasma cells. Heavy deposits of IgA were found within duct lumina. IgA, IgG_(a,b,c) and IgG(T) were localized intercellularly in the interstitial connective tissue of salivary glands.     

Antibody response in the parotid fluid and serum of Irus monkeys (Macaca fascicularis) after local immunization with Streptococcus mutans.

The antibody response of Macaca fascicularis in parotid saliva and serum to local immunization by two routes with Streptococcus mutans was studied and compared over 1 year. Antibodies were titrated and classified by indirect immunofluorescent staining using specific antiglobulin conjugates. Antiglucosyltransferase activity was assayed by an enzyme inhibition test. Animals were immunized first by injecting formalin-killed bacterial cells and cell products subcutaneously into the vicinity of the four major salivary glands. The monkeys were next immunized by retrograde instillation of antigen into the parotid duct. Extensive subcutaneous local immunization gave a serum response only. After parotid duct immunization, high titers of immunoglobulin A (IgA) antibody, along with traces of immunoglobulin G (IgG) immunoglobulin M (IgM) antibody, appeared in the parotid saliva, and in the serum high titers of IgG antibody were present along with lower titers of IgA and IgM. IgA antibodies in parotid fluid were shown by double immunofluorescent staining to be associated with antigenic determinants which cross-reacted with an antiserum directed to human secretory component. Titers in parotid fluids and sera fell sharply when immunization was stopped. This response pattern was reproducible. High concentrations of antibody capable of inhibiting glucosyltransferase prepared from S. mutans were found in the sera, but relatively little was detected in the parotid fluids. Extensive immunization via the parotid duct resulted in transient functional impairment of the gland, as evidenced by diminished salivary flow rates. We conclude that parotid ductal immunization can be an effective method for stimulating a salivary secretory IgA antibacterial antibody response.     

Immunological features of minor salivary gland saliva

Concentrations of IgA, IgG, IgM, and IgA subclasses were measured in 138 pairs of parotid gland saliva (PS) and labial gland saliva (LS), using an enzyme-linked immunosorbent assay (ELISA) technique in which levels of Ig were quantitated using affinity-purified anti-heavy chain reagents for capture and development. Both PS and LS were collected simultaneously during sour lemon drop stimulation. As previously observed, IgA was the dominant immunoglobulin in both salivary fluids, the concentrations of which were highly correlated within the subjects studied. The mean proportion of IgA1 to total IgA was slightly higher in LS (0.66), compared with PS (0.60). Little IgM was usually detected in either secretion. In contrast, LS had IgG concentrations (mean, 8.1 µg/ml) which were significantly higher (P<0.001) than those found in parotid saliva (mean, 0.3 µg/ml). Over 30% of the subjects had mean LS IgG levels above 10 µg/ml. The mean percentage of LS IgG to IgA was 20% in the 138 samples tested. Gel filtration of pairs of PS and LS from four individuals revealed IgM, IgA, and IgG to elute in positions commensurate with pentameric IgM, secretory IgA, and monomeric IgG. Little or no monomeric IgA could be detected. These results suggest that, in addition to IgA, the IgG isotype may also be important in antibody-mediated phenomena which occur in oral microenvironments bathed by minor salivary gland secretions.     

The cellular basis of salivary immunity in the mouse: incidence and distribution of B cells, T cells and macrophages in single-cell suspensions of the major salivary glands

A multiparametric analysis of the resident immune populations in the parotid, submandibular and sublingual salivary glands was done in single-cell suspensions. The incidence of T and B cells and of macrophages was assessed using phenotypic markers in immunofluorescent staining and a functional assay was used to enumerate immunoglobulin (Ig)-secreting cells. Characteristic frequencies and isotype distributions of cytoplasmic Ig+ B cells and surface Ig+ B lymphocytes were found in the three types of glands. Even though IgA was always found to be the predominant isotype in individual salivary secretions (90-93%) this was not directly correlated by an absolute predominance of IgA-secreting cells in the glands (45-65%). Significant percentages of T cells (Thy-1+ and Lyt-1+ cells: 3-4%) and macrophages (Mac 1+ and esterase-positive cells: 3-10%) were also recovered in our suspensions. It is therefore concluded that the murine salivary glands contain both effector and regulatory cells required for the development and expression of salivary immunity.     

Detection of human herpesvirus 6 and human herpesvirus 7 in the submandibular gland, parotid gland, and lip salivary gland by PCR.

In order to define the major sites of persistence of human herpesvirus 6 (HHV-6) and HHV-7, PCR with DNAs from more than 100 specimens of 3 different salivary glands was performed. HHV-6 DNA was detected in 52 (88.1%) of 59 submandibular gland, 17 (63.0%) of 27 parotid gland, and 9 (52.9%) of 17 lip salivary gland specimens. On the other hand, HHV-7 DNA was detected in 59 (100%) of 59 submandibular gland, 23 (85.2%) of 27 parotid gland, and 10 (58.8%) of 17 lip salivary gland specimens. These findings demonstrate that salivary glands are a site of persistent infection of both HHV-6 and HHV-7 and that among the three types of salivary gland examined, the submandibular gland is the primary one in which these herpesviruses, especially HHV-7, persist.     

Nerve-evoked secretion of immunoglobulin A in relation to other proteins by parotid glands in anaesthetized rat

Secretion of fluid and proteins by salivary cells is under the control of parasympathetic and sympathetic autonomic nerves. In a recent study we have shown that, in the rat submandibular gland, autonomic nerves can also increase the secretion of IgA, a product of plasma cells secreted into saliva as SIgA (IgA bound to Secretory Component, the cleaved poly-immunoglobulin receptor). The present study aimed to determine if parotid secretion of SIgA is increased by autonomic nerves and to compare SIgA secretion with other parotid proteins stored and secreted by acinar and ductal cells. Assay of IgA in saliva evoked by parasympathetic nerve stimulation immediately following an extended rest period under anaesthesia indicated that it had been secreted into intraductal saliva in the absence of stimulation during the rest period. The mean rate of unstimulated IgA secretion (2.77+/-0.28 microg min(-1) g(-1)) and the 2.5-fold increase in IgA secretion evoked by parasympathetic stimulation were similar to results found previously in the rat submandibular gland. Sympathetic nerve stimulation increased SIgA secretion 2.7-fold, much less than in the submandibular gland. SDS-PAGE and Western blot analysis with anti-IgA and anti-Secretory Component antibodies confirmed that SIgA was the predominant form of IgA in saliva. Acinar-derived amylase and ductal-derived tissue kallikrein were more profoundly increased by parasympathetic and particularly sympathetic stimulation than SIgA. Overall, the results of the present study indicate that SIgA forms a prominent component of unstimulated parotid salivary protein secretion and that its secretion is similarly increased by stimulation of either autonomic nerve supply. The secretion of other parotid salivary proteins that are synthesized and stored by acinar or ductal cells is upregulated to a much greater extent by parasympathetic and particularly sympathetic stimulation.     

Immunoglobulins in certain CNS disorders: a study of CSF Ig classes G, A, M, D, and E concentrations

Concentrations of cerebrospinal fluid (CSF) Ig classes G, A, M, D, and E have been reported in various neurologic disorders, viz, aseptic meningitis, multiple sclerosis, benign tumor, malignant tumor, and hydrocephalus. In aseptic meningitis, IgG and IgM were found to be either normal or elevated, whereas concentrations of IgA, IgD, and IgE were normal. Multiple sclerosis patients had IgG, IgA, and IgM, either normal or elevated, but IgD and IgE were on the lower end of the normal. Malignant tumor patients had elevated concentrations of IgG, IgA, IgM, and IgE, but their IgD was on the lower end of the normal. In benign tumor population IgA and IgE, and in hydrocephalus IgG and IgA, were found to be elevated in most of the patients. On statistical analysis, significant differences were observed between the means of the normal group and that of the patients' group for all the five immunoglobulins. By linear regression, a statistical relationship was observed between IgA - IgG, IgM - IgG, IgA - IgM and IgA + IgM - IgG in these neurologic disorders.     

Significance of different J chain profiles in human tissues: generation of IgA and IgM with binding site for secretory component is related to the J chain expressing capacity of the total local immunocyte population, including IgG and IgD producing cells, and depends on the clinical state of the tissue

Most IgA producing cells in normal intestinal and nasal mucosa synthesize dimers or larger polymers as evidenced by 90% cytoplasmic affinity for secretory component (SC) in vitro and almost 100% J chain positivity. The comparable median figures for normal exocrine glands (salivary, lacrimal, lactating mammary) were 84% and 92%, respectively. Conversely, IgA immunocytes in the subepithelial areas of palatine tonsils and in other extraglandular tissues, such as inflamed gingiva and intestinal submucosa, showed only 16-28% SC binding capacity and 18-51% J chain positivity. Similarly decreasing J chain expression, from glandular to extraglandular sites, was revealed not only for IgM immunocytes but also for those producing IgD or IgG, particularly the latter. This observation indicated more extensive overall clonal maturation in tissues without glandular elements since J chain expression seems to be a feature of relatively early memory B cells. The results were supported by studies in patients with selective IgA deficiency. Inflammatory disease caused significantly reduced SC binding capacity of IgA cells, both in intestinal mucosa and tonsils; this change was paralleled by decreased J chain expression, not only for mucosal and tonsillar IgA cells but also for mucosal IgG cells, suggesting local appearance of more mature clones. The resulting change to production of monomeric IgA may adversely affect secretory immunity and thus contribute to perpetuation of chronic inflammatory disease.     

Immunohistochemical localization of chromogranin a in the acinar cells of equine salivary glands contrasts with rodent glands

We investigated the existence of chromogranin A (CgA) in salivary glands of the horse by Western blotting and enzyme immunoassay (EIA) using an antiserum against a peptide sequence of equine CgA. We also compared its cellular distribution between the horse and rat salivary glands with a tyramide signal amplification immunofluorescence technique. Western blotting gave three significant immunoreactive bands (74, 56 and 48 kDa) in adrenal medulla and three major salivary glands of horses. Immunoreactivities for CgA measured by EIA in horses were 154.05 +/- 41.46, 20.32 +/- 5.59 and 4.43 +/- 2.23 pmol/g wet weight in the parotid gland, submandibular gland and sublingual gland, respectively, and 1.03 +/- 0.407 pmol/mg protein in the saliva. Immunohistochemically, the positive reactivity was mainly recognized at acinar cells in equine salivary glands. This exhibits a contrast to the finding in the rat salivary glands that the CgA immunoreactivity is localized at the duct cells of the submandibular gland. These results provide novel evidence that in the horse, CgA is stored in the acinar cells of salivary glands, and secreted into saliva.     

Immunohistochemical characterization of intracellular J-chain and binding site for secretory component (SC) in human immunoglobulin (Ig)-producing cells

J-chain staining of IgA- and IgM-producing immunocytes was significantly enhanced when tissue sections were pretreated with acid urea, apparently because molecular unfolding exposed concealed J-chains. This indicated substantial completion of the Ig polymers at the cytoplasmic level, which was verified by diffuse binding of SC in vitro to the cytoplasm of most J-chain-positive IgA and IgM cells. This process involved specific non-covalent forces which showed the same interrelation as that noted for isolated dimeric IgA and 19S IgM--the latter as well as IgM cells exhibiting stronger binding of SC than the IgA counterparts. Conversely, J-chain staining of IgD and IgG immunocytes was not enhanced by acid urea and these cells did not generally express affinity for SC; rare exceptions could apparently be ascribed to artifacts or dual isotype production including IgA or IgM polymers. Parallel demonstration of J-chain and SC binding seems to be the best available method for studies of polymer-producing immunocyte populations and offers the advantage of in situ evaluation of cell distribution in relation to morphology. The reliability of this approach was attested to by the fact that IgA immunocytes in all secretory tissues investigated (salivary, mammary and lacrimal glands; nasal and intestinal mucosae) expressed J-chain (87-97%) and SC affinity (84-87%) in comparable proportions, indicating that almost 90% of the cells were engaged mainly in dimer production. The observation that most IgD and 50-70% of the IgG immunocytes in secretory tissues expressed J-chain, has implications for the differentiation of B-cell clones homing to such sites. Conversely, IgG cells in extra-glandular tissues showed strikingly reduced J-chain production and such sites contained IgA immunocytes with heterogeneous expression of J-chain and SC affinity. Thus, in the extra-follicular area of palatine tonsils 70-80% of the IgA cells seemed to be pure monomer producers and the remainders apparently generated a mixed product. Most immunocytes in extra-glandular tissues may therefore belong to mature clones with completely or partially repressed J-chain synthesis.     

Beta-adrenergic receptors and salivary gland secretion during aging.

Beta-adrenergic signal transduction is primarily responsible for the control of the protein secretions by salivary cells. To examine the relationship between beta-adrenergic signal transduction and beta-adrenergic agonist-stimulated salivary secretion, we simultaneously assessed beta-adrenergic receptor number and pilocarpine-isoproterenol-stimulated salivary flow and secreted proteins in parotid and submandibular glands from 3-, 12- and 24-month-old female NNIA F-344 rats. There were no age-related changes in the density of beta-adrenergic receptors in the parotid gland or in the submandibular gland. In the parotid gland there was a significant increase in saliva flow rate in the oldest age group and no changes in the amount of total proteins secreted over 30 min. However, when normalized to gland weight, flow rate was unchanged and the amount of total secreted proteins decreased with age. In the submandibular gland there were age-related increases in both absolute volume and total secreted protein, but when normalized to gland weight there were no longer changes with age. Changes in flow rate were paralleled by reciprocal changes in protein secretory function such that changes in the salivary protein concentrations for the most part were unchanged with age for both the parotid and the submandibular gland. These parameters were compared to our previous data on adenylate cyclase activity, and collectively, these data suggest that in the submandibular gland salivary secretory function does not correlate with changes in beta-adrenergic receptor density or isoproterenol-stimulated adenylate cyclase activity.