Immunosenescence and mucosal immunity: significant effects of old age on secretory IgA concentrations and intraepithelial lymphocyte counts.

Gu , 1992, 33, 882-886 Immunosenescence and mucosal immuni y: signi ican e ec s o old age on sec e o y IgA concen a ions and in aepi helial lymphocy e coun s E A anz, S O'Mahony, J R Ba on, A Fe guson Abs ac Concen a ions o immunoglobulins (Ig) and le els o iso ype speci ic an ibodies o h ee die a y an igens in se um, pu e pa o id sali a, and in in es inal sec e ions ob ained by whole gu la age om g oups o heal hy elde ly subjec s (aged >70 yea s) and o younge adul con ols (aged 25-50 yea s) we e measu ed. In addi ion, coun s o lamina p op ia and in a- epi helial lymphoid cells we e pe o med in his ologically no mal jejunal biopsy specimens om elde ly and younge subjec s. Elde ly subjec s had signi ican ly highe concen a- ions o se um and sali a y IgA and o sali a y IgM (bo h, p<0.01), and o sali a y IgA an i- bodies han did he younge subjec s, bu he amoun o immunoglobulin and an ibody in whole gu la age luid was simila in he wo age g oups. Jejunal biopsy specimen cell coun s showed highe IgA plasma cell coun s and lowe in aepi helial lymphocy e coun s in he elde ly g oup (p<0.01), wi h simila coun s o IgM and IgG plasma cells, eosinophils, and mas cells in he wo g oups. The e is e idence o signi ican e ec s o old age on he mucosal immune sys em. ga ion o gas oin es inal symp oms, and in whom he inal diagnosis was o unc ional gas oin es inal symp oms o o a mino clinical p oblem wi hou e idence o immunological, in ec ious, neoplas ic, o alle gic disease. In o - ma ion was eco ded on ac o s possibly ele an o mucosal immuni y, including smoking and alcohol consump ion, die a y habi s, den i ion, and medica ion. Se ies A Fo s udies on se um and sali a, elde ly olun- ee s we e ec ui ed om old people a ending he ge ia ic day cen e a he Royal Vic o ia Hospi al and younge subjec s om pa ien s o he Gas o-In es inal Uni a he Wes e n Gene al Hospi al, Edinbu gh. Se ies B Whole gu la age luid was ob ained om pa ien s o he Gas o-In es inal Uni who we e ha ing gu la age wi h a polye hylene-glycol- elec oly e la age solu ion, Goly ely, as p e- pa a ion o ba ium enema o colonoscopy. I a e clinical assessmen he inal diagnosis was as desc ibed abo e, he pa ien s we e included in he s udy. Gas o-In es inal Uni , Uni e si y o Edinbu gh and Wes e n Gene al Hospi al, Edinbu gh E A anz S O'Mahony J R Ba on A Fe guson Co espondence o: P o esso A Fe guson, Depa men o Medicine, Uni e si y o Edinbu gh, Wes e n Gene al Hospi al, Edinbu gh EH4 2XU Accep ed o publica ion 18 No embe 1991 The e ha e been many esea ch s udies o ageing and immuni y, bu hey ha e concen a ed on sys emic immuni y in man o ha e been con- duc ed in aged oden s.' 3 The e ha e been no ho ough s udies in humans o he in luence o ageing on sec e o y immune unc ion o on in es inal cellula immuni y. We epo he e he esul s o measu emen s o immunoglobulins and o iso ype speci ic an ibodies o h ee die a y an igens in se um, pu e pa o id sali a, and in in es inal sec e ions ob ained by whole gu la age om a g oup o heal hy elde ly subjec s (aged >70 yea s) and om younge adul con ols (aged 25-50 yea s). In addi ion, coun s o lamina p op ia and in aepi helial lymphoid cells we e pe o med in his ologically no mal jejunal biopsy specimens om elde ly and younge subjec s. Me hods PATIENTS AND VOLUNTEERS 'Elde ly' subjec s we e aged 70 yea s o mo e; 'younge ' subjec s we e aged 20-50 yea s. Some we e heal hy olun ee s. O he s we e pa ien s who had had ull clinical assessmen and in es i- Se ies C Jejunal biopsy specimens we e selec ed om a ile o s o ed slides, i (i) he pa ien ell wi hin he age anges de ined, (ii) his ology had been epo ed o be no mal by a consul an pa h- ologis , (iii) assays o b ush bo de disaccha i- dases we e no mal, and (i ) i e iew o he case no es showed no e idence, on inal clinical app aisal, o immunological o o he signi ican disease as speci ied abo e. SPECIMEN COLLECTION Pu e pa o id sali a A imed i e minu e collec ion o pa o id sali a was ob ained a e a as o a leas h ee hou s, ia a Ca lsson-C i enden cup placed o e he pa o id duc o i ice.4 In es inal luid Whole gu la age luid (WGLF) was ob ained by gi ing he pa ien s iso onic non-abso bable polye hylene-glycol-elec oly e la age solu ion (Goly ely) o a maximum o 4 li es o ally a e an o e nigh as .5 Specimens we e collec ed o he s udy when hey became clea , wi hou aecal 882 on Augus 23, 2020 by gues . P o ec ed by copy igh .h p://gu .bmj.com/Gu : i s published as 10.1136/gu .33.7.882 on 1 July 1992. Downloaded om Immunosenescence and mucosal immuni y: signi ican e ec s o old age on sec e o y IgA concen a ions and in aepi helial lymphocy e coun s con amina ion. The specimens we e immedi- a ely cen i uged and ea ed wi h p o ease inhibi o s. Se um, sali a, and gu la age specimens we e s o ed in aliquo s a -70C. ELISA TECHNIQUES All samples we e assayed o o al IgA, IgG, and IgM and o speci ic an ibodies o hese iso ypes o h ee ep esen a i e ood p o ein an igens gliadin, o albumin, and lac oglobulin, by enzyme linked immunoso ben assays (ELISAs) as p e iously desc ibed.6 Re e ence s anda ds o Ig concen a ions we e human colos al IgA (Sigma Chemical Co, Poole, Do se ) and a human e e ence se um o IgG and IgM (P o ein Re e ence Uni , Royal Hallamshi e Hospi al, She ield). Se um om an un ea ed coeliac disease pa ien was used as a e e ence s anda d o an ibodies. Pla es we e ead in an MR580 mic oELISA eade (Dyna ech, Billingshu s , Sussex, UK), se a a wa e leng h o 405 nM (OD405), when he s anda d eached an a bi a ily selec ed OD405 o 1-0, and an ibody le els in es specimens we e exp essed as a pe cen age o he op ical densi y o he s anda d. The ollowing me hod was used o measu e- men o sec e o y IgA in WGLF: ELISA pla es we e coa ed as o o al IgA (an i-a chain), and s anda d colos um IgA and samples we e added in duplica e o o e nigh incuba ion; wo di e en conjuga es we e used including an i- human IgA ( o o al IgA, dilu ion 1:5000) and an i-human sec e o y componen /alkaline phos- pha ase conjuga e (dilu ion 1:2000) (The Binding Si e, Bi mingham B15 2SQ, UK). The op ical densi y alues ob ained o o al IgA and sec e o y componen we e compa ed o each gu la age sample. JEJUNAL BIOPSY SPECIMENS: STAINS AND COUNTING TECHNIQUES Biopsy specimens om bo h g oups we e o malin ixed, embedded in pa a in wax, and s ained wi h: (i) Haema oxylin and eosin, in o de o s udy he illus/c yp mo phology and in aepi helial lymphocy e coun s; (ii) Immunope oxidase echnique o s udy immunoglobulin con aining cells. B ie ly, sec ions we e p e ea ed wi h ypsin 0-1% in T is bu e ed saline pH 7-6 a 37°C o 20 minu es, and hen se ially incuba ed wi h p ima y an ibody (sheep an i-human IgG, IgA, TABLE I Demog aphic da a o elde ly and younge subjec s - se ies A, B, and C Se ies A Se ies B Se ies C Se um/sali a Gu La age Jejunal specimens Elde ly Young Elde ly Young Elde ly Young No 43 37 16 14 27 25 Male/ emale 14:29 14:23 6:10 4:10 6:21 7:18 Mean age 79.3 36-2 79-2 32-2 75 5 36-3 ( ange) (70-94) (26-50) (71-92) (23-47) (70-87) (27-50) Smoke s 14 10 2 6 7 9 Alcohol 15 23* 4 8 17 20 Den u es 41 26** 16 1** 15/15 4/25 *p<O-Ol; **p<O-O0l. IgM a 1:500, 1:250, and 1:200 dilu ions, espec- i ely); seconda y an ibody (a ini y pu i ied donkey an i-sheep/goa IgG a 1:50 dilu ion); and e ia y an ibody (sheep pe oxidase/an i- pe oxidase a 1:80 dilu ion). All incuba ions we e ca ied ou in a humid chambe a oom empe a u e o 60 minu es. An ise a we e ob ained om he Sco ish An ibody P oduc ion Uni , Ca luke, Sco land; posi i e and nega i e speci ici y con ols we e included in each ba ch; (iii) Toluidine blue and ca bol ch oma ope o mas cells and eosinophils espec i ely. Blinded cell coun s, on s ained sec ions which had been coded and mixed, we e pe o med wi h a Lei z mic oscope, using app op ia e eyepieces and g a icules, calib a ed wi h a s age mic o- me e . Villus and c yp leng h measu emen s we e pe o med wi h a 1 cm linea eyepiece g a icule and a x 10 and x40 objec i e lens espec i ely. In aepi helial lymphocy e coun s we e pe - o med by a me hod p e iously desc ibed7 wi h a 1 cm squa e g a icule and a x 100 oil imme sion lens, exp essing he esul s in numbe s o in a- epi helial lymphocy es pe 100 illus en e ocy es. Coun s o plasma cells, mas cells, and eosinophils we e pe o med wi h he same g a icule and eyepiece as o in aepi helial lymphocy e coun s. Only well o ien a ed sec ions we e used; ields we e examined sys ema ically, s a ing wi h he base o he g a icule a he muscula is mucosae, coun ing sequen ial ields o lamina p op ia e ically o he luminal su ace, hen ealigning he g a icule on he immedia ely adjacen pa o he muscula is mucosae and con inuing he p ocess. Epi helium was excluded, and whe e only pa o a ield comp ised lamina p op ia, he p opo ion was es ima ed by eye. A leas 40 lamina p op ia g a icule ields pe sec ion we e coun ed. The g id a ea wi h a x 100 objec i e was 0-0132 mm2. The esul s we e exp essed as numbe s o posi i e cells/mm2 o lamina p op ia issue. STATISTICAL METHODS Di e ences in immunoglobulin concen a ions, an ibody le els, and cell coun s we e assessed using he Mann-Whi ney U es ( wo- ailed) and co ela ions wi h Spea man's ank co ela ion coe icien . A p alue <0 05 was conside ed signi ican . Resul s DETAILS OF SUBJECTS Demog aphic da a o he pa ien s in whom humo al immuni y was assessed a e summa ised in Table I. Sex dis ibu ion was simila in he elde ly and young g oups. Den u e use was signi ican ly mo e common in he elde ly, and, in he subjec s whose se um and sali a we e s udied, alcohol use was less equen han in young subjec s. SERUM IMMUNOGLOBULINS AND ANTIBODIES In elde ly subjec s, he se um IgA concen a ion was highe and he IgM concen a ion lowe han 883 on Augus 23, 2020 by gues . P o ec ed by copy igh .h p://gu .bmj.com/Gu : i s published as 10.1136/gu .33.7.882 on 1 July 1992. Downloaded om A anz, O'Mahony, Ba on, Fe guson in he young (Table II). Se um concen a ions o IgM class an ibodies o h ee die a y p o eins we e also signi ican ly lowe in he elde ly han in he young (Table III). IMMUNOGLOBULINS AND ANTIBODIES IN PAROTID SALIVA In pu e pa o id sali a, IgA concen a ions we e app eciably highe in he elde ly han in he young (Table II). The e was a signi ican posi i e co ela ion be ween he sali a y IgA concen- a ion and age in he elde ly g oup ( =0-309, p<005). Concen a ions o IgM and IgG we e also signi ican ly highe in he elde ly. Concen- a ions o IgA class an ibody o gliadin, o albumin, and ,B lac oglobulin in sali a we e high in elde ly subjec s, and ace amoun s o IgG class an ibody o wo o he h ee an igens we e de ec ed. WHOLE GUT LAVAGE FLUID S udies o in es inal luid, howe e , showed no di e ences in o al immunoglobulin concen- a ions (Table II) o speci ic an ibody alues TABLE II Immunoglobulin concen a ions (median ( ange)) in se um and sec e ions o elde ly andyoung subjec s (Se ies A, B) Elde ly Young No Median ( ange) No Median ( ange) p Value Se um (se ies A): IgA ([ g/ml) 43 2737-8 37 2062 p<0-001 (9413-1031) (3682-845) IgM ([g/ml) 43 922-2 37 1357 p<005 (5498-270) (3445-322) IgG ([ g/ml) 43 11223 37 10 527 NS (25 490-6090) (15 921-7743) Pa o id sali a (se ies A): IgA ([ g/ml) 43 205.4 37 113-4 p<0-001 (3229-30.7) (553-216) IgM([ g/ml) 43 1-6 37 1.1 p<005 (42.6-0) (5.5-0) IgG ([ g/ml) 43 1-7 37 0.5 p<0-001 (45.8-0) (34.2-0.1) Whole gu la age luid (se ies B): IgA (Ig/ml) 16 69-9 14 69-1 NS (226-8) (274-10-6) IgM([kg/ml) 16 3-6 14 5-8 NS (20-1-1-4) (35.8-0) IgG(,ug/ml) 16 0-1 14 0-7 NS (9.8-0) (2-1-0) TABLE III Le els o an ibodies o h ee die a y p o eins in se um and sec e ions (median ( ange)) o elde ly and young subjec s (Se ies A, B) Elde ly Young No IgA IgM IgG No IgA IgM IgG Se um an ibodies (se ies A): Gliadin 43 8-2 39.5 17 37 4.5 88.3* 15-5 (0-150) (15-155) (0-111) (0-60-6) (14-222) (26-63) O albumin 43 5 14-6 23-4 37 3-2 21.6** 30-5 (1*3-81-6) (2-3-76) (0-98.5) (1-150) (5-49) (2-1-37) ,B Lac oglobulin 43 9-3 20-3 36-3 37 9.2 29.2** 29-8 (2-150) (4-50) (3-108-4) (0-9-37) (8-90-8) (3-7-101-6) Pa o id sali a an ibodies (se ies A): Gliadin 43 11.5* 4-5 0 37 3-8 4-6 0 (1-6-81) (0-66) (0-5-3) (0-304) (0-24-5) (0-2-3) O albumin 43 15.3** 0-1 0 37 9-1 1 0 (3-4-116-7) (0-21-3) (0-6-1) (0-73.5) (0-15-5) (0-7-9) 6 Lac oglobulin 43 31-8** 1-5 0.3* 37 20.5 1 0 (5-150) (0-53) (0-11-3) (3-101-6) (0-255) (0-0 6) Whole gu la age luid an ibodies (se ies B): Gliadin 16 6-2 6-3 0 14 3-2 5 3 0-3 (0-85-9) (0.5-62 8) (0-6.5) (0-57-8) (0-36-2) (0-3.3) O albumin 16 3.5 1-2 0 14 3-3 1-6 0.5 (0-71-5) (0-5.9) (2-2.5) (0.6-32-9) (0-4 7) (0-44) ,B Lac oglobulin 16 5.3 1-2 0 14 5 2 0-2 (1-42) (0-7) (0-3-3) (0-76) (0-20-6) (0-3.6) *p<O.OOl; **p<O.05. TABLE IV Concen a ion o o al IgA and sec e o y IgA (median ( ange)) in whole gu la age luid om elde ly and young subjec s (Se ies B) Elde ly Young No 16 14 To al IgA (jsg/ml) 189-7 186-5 (470-7-11-9) (531-2-13) Sec e o y IgA (Isg/ml) 167-6 111-4 (439-6-14-9) (508-23-4) SIgA, % o o al 92 80 (100-74-1) (100-51) when elde ly and young subjec s we e com- pa ed. The assay o SIgA concen a ion in WGLF was de eloped only ecen ly, and su icien ma e ial o analysis emained om 12 elde ly and 12 younge subjec s. Values we e simila o o al IgA, SIgA, and he pe cen age o IgA as sec e o y (mean 92%, ange 100-74 1 in he elde ly g oup; and mean 80%, ange 100-51 in younge con ols) (Table IV). CELL COUNTS The biopsy specimens om elde ly and young pa ien s all looked his ologically no mal; illus and c yp leng hs we e simila in he wo g oups. These measu emen s, and coun s o in aepi helial lymphocy es and lamina p op ia lymphoid cells, a e summa ised in Table V. In he elde ly pa ien s, coun s o in aepi helial lymphocy es (exp essed pe 100 illus en e o- cy es) we e signi ican ly lowe (p<004) and o lamina p op ia IgA con aining plasma cells signi ican ly highe (p<001) han in he younge con ols. Coun s o o he lamina p op ia cells (IgG plasma cells, IgM plasma cells, mas cells, eosinophils) we e simila in he wo g oups. Discussion T adi ional me hods o immunological in es i- ga ion applied o sys emic immuni y ha e clea ly shown a phenomenon o immunosenescence.'-3 The hymus is a ophic by he age o 60 yea s and pe iphe al T lymphocy es ha e impai men o p oli e a i e capaci y, a educed sec e ion o cy okines in esponse o a ious signals, and a educed a e o ecep o exp ession when app op ia ely s imula ed.3 8-11 B cells a e in insically no mal in old age bu unc ion in an abe an way. This is e lec ed by high concen a ions o immunoglobulins in he blood, high i es o a ious au oan ibodies,'2 '3 and ye an impai ed gene a ion o speci ic an i- body in esponse o an igen encoun e .'2 14 Se e al ac o s p obably con ibu e o his abno mali y o B cells: de icien T cell help and also de icien T supp ession o inapp op ia e unc ion3; he ac ha a e a li e ime o exposu e, idio ype/an i-idio ype immuno- supp essi e loops ha e o med'5; o ha mos B cells a e p ecommi ed lea ing li le capaci y o a b isk esponse o u he an igen encoun e . The e is gene al ag eemen ha se um IgA concen a ions a e inc eased in old age in a ange o species including man.'6 7 P e ious wo k on sec e o y immuni y in man in old age has mainly conce ned s udies wi h mixed sali a. '7 These s udies can be c i icised because no accoun is 884 on Augus 23, 2020 by gues . P o ec ed by copy igh .h p://gu .bmj.com/Gu : i s published as 10.1136/gu .33.7.882 on 1 July 1992. Downloaded om Immunosenescence and mucosal immuni y: signi ican e ec s o old age on sec e o y IgA concen a ions and in aepi helial lymphocy e coun s 885 TABLE V Measu emen o illi and c yp s, and coun s o in aepi helial lymphocy es and lamina p op ia lymphoid cells, in jejunal biopsy specimens om elde ly and young subjec s (Se ies C) Elde ly (n=27) Young (n=22) Pa ame e Median ( ange) Median ( ange) p Value Villous heigh (,um) 286-7 313-6 NS (347-5-215-3) (490 2-208 3) C yp dep h (gm) 94-2 96 5 NS (132-2-63-6) (170-2-63-1) In aepi helial lymphocy es 17-5 23 p<005 (% en e ocy es) (316-12) (37-15) IgA-plasma cells 744-8 310-5 p<001 (/mm lamina p op ia) (1133-294) (680-119) IgM-plasma cells 244-8 221-7 NS (5426-172) (317-6-47) IgG-plasma cells 28-4 22-7 NS (141-7-7-6) (43 5-9 4) Mas cells 255-8 233-6 NS (335-89) (337-129-5) Eosinophils 190-3 127-3 NS (317-22-7) (3024-38 4) aken o den i ion o den al hygiene so he mixed sali a is likely o be hea ily con amina ed wi h c e icula luid. In his epo we p esen an essen ially desc ip i e s udy, a i s a emp o iden i y any g oss abe a ions o sec e o y immune unc ion in elde ly humans. We ha e made use o olun- ee heal hy old people o s udy se um and pu e pa o id sali a, and ma e ial which has become a ailable om old people, in e ospec consid- e ed o ha e essen ially no mal gas oin es inal ac s, bu who ha e had ei he whole gu la age o small bowel biopsy in he cou se o in es i- ga ion in a busy gas oin es inal uni . Absolu e concen a ions o immunoglobulins and an ibodies in a sec e ed luid will be in lu- enced by low a e'8 as well as by he immuno- logical unc ion o he issue conce ned. This is pa icula ly ele an o he in e p e a ion o ou indings o gene ally highe concen a ions o immunoglobulins in he sali a o elde ly sub- jec s. This could be explained en i ely i sali a y low a e is signi ican ly slowe in old people han in younge indi iduals. The e a e no da a on low a es o pu e pa o id sali a in old age, bu in a s udy o mixed sali a, mean low a es and p o ein concen a ions we e simila in g oups o indi iduals aged 26-44 and 65-83 yea s. 19 We ha e ound ha a gene al inc ease in IgA p oduc ion occu s in he gas oin es inal ac as well as in he se um in old age. The pu e pa o id sali a y IgA concen a ion was app eciably highe in he elde ly g oup, showing a posi i e co ela ion be ween IgA and age. IgM and IgG concen a ions we e also inc eased. Al hough concen a ions o IgA in whole gu la age luid we e simila in old and younge people, IgA plasma cell coun s we e signi ican ly highe ; his me hod is p obably mo e sensi i e as an index o mucosal IgA s a us han analysis o luid ob ained in he cou se o s anda d wa d o ou pa ien la age bowel p epa a ion. We a e now de eloping an expe imen al p o ocol o s eady s a e whole gu pe usion which will allow us o measu e he hou ly a e o sec e ion o immuno- globulins and o he subs ances. The p esen s udy o whole gu la age luid has, howe e , enabled us o es ablish ha mos o he IgA in in es inal sec e ions is bound o sec e o y componen - ha is, polyme ic - and ha in his espec he molecula o m o IgA in he sec e ions in old age is simila o ha o he young. The high concen a ions o IgA in se um and sali a a e pa allelled by high le els o speci ic an ibody o IgA class o h ee die a y p o ein an igens, ma ke s o a 's eady s a e' an ibody s a us o he indi iduals conce ned. Techniques a e now a ailable o allow measu emen o he kine ics o immune esponse o a accine o o he en e ically adminis e ed an igen and hese should now be applied in old people and could be used o es he hypo hesis ha in es inal s asis and/o changes in colonic lo a induce polyclonal syn hesis o IgA ia immunomodula o y G am nega i e bac e ial p oduc s.20 Dec eased e iciency o Kup e cell unc ion could be ele an .20 Se um IgM an ibody le els o he h ee ood an igens s udied we e lowe in he elde ly g oup, as was he le el o IgA an igliadin an ibody in se um. These indings a e in ag eemen wi h a p e ious epo ,2' al hough we ound se um IgG an ibody le els o be simila in he wo age g oups. Low le els o se um IgM an ibody could be clinically ele an , o hese ha e been shown o co ela e wi h a highe equency o in ec ion wi h capsula e bac e ia.2223 Old age does no , howe e , ha e a global e ec on IgM, as he e we e simila le els o IgM and IgM an ibodies in he sali a and gu la age luid om old and young subjec s. Ou s udies o jejunal biopsy specimen pa h- ology showed no e idence o mucosal a ophy in he jejunum o old people; his suppo s a ecen epo by Co azza e al.24 We ha e had simila coun s o mos o he lamina p op ia cell ypes s udied in biopsy specimens om old and younge people, which adds weigh o he signi icance o he indings ha di e ences eme ge o wo cell ypes. A high coun o IgA plasma cells has al eady been discussed. The inding o a low in aepi helial lymphocy e coun (exp essed as lymphocy es pe 100 illus en e ocy es) equi es con i ma ion and u he ollow up in p ospec i ely collec ed biopsy specimens. I is necessa y o use ozen sec ions o de ailed examina ion o he pheno ype o in aepi helial lymphocy e. Fu he s udies should include coun s o CD4 and CD8 posi i e cells; iden i ica ion o he T cell ecep o ypes (alpha be a o gamma del a) and he p esence o ac i a ion ma ke s. I will be pa icula ly in e es ing i de iciency o a subse o in aepi helial lymphocy e is ound, and i his could be linked o he expan- sion o IgA locally. This expe imen o na u e migh con ibu e e y use ul da a o he in es i- ga ion o whe he o no in aepi helial lympho- cy e unc ion as locally ac i e supp esso cells.25 This wo k has been suppo ed by g an s om he Sandoz Founda ion o Ge on ological Resea ch and om he Sco ish Hospi als' Endowmen Resea ch T us . We hank M s J Johns on and M J Bode o echnical assis ance, D S Walsh o access o he pa ien s, and he s a o he GI In es iga ion sui e o hei in aluable suppo in he collec ion o specimens. 1 Makinodan T, Kay MMB. Age in luence on he immune sys em. Ad Immunol 1980; 29: 287-330. 2 Wade AW, G een-Johnson J, Szewzuck MR. Func ional changes in sys emic and mucosal lymphocy e epe oi es wi h age: an upda e e iew. Aging. Immunol In ec Dis 1988; 1: 65-97. on Augus 23, 2020 by gues . P o ec ed by copy igh .h p://gu .bmj.com/Gu : i s published as 10.1136/gu .33.7.882 on 1 July 1992. Downloaded om 886 A anz, O'Mahony, Ba on, Fe guson 3 Thoman ML, Weigle WO. The cellula and subcellula basis o immunosenescence. Ad Immunol 1989; 46: 221-61. 4 Ba on JR, Riad M, Gaze MN, Ma an AGD, Fe guson A. Mucosal immunode iciency in smoke s, and in pa ien s wi h epi helial head and neck umou s. Gu 1990; 31: 378-82. 5 O'Mahony S, Ba on JR, C ich on S, Fe guson A. Gu la age: a new app oach o he s udy o in es inal humo al immuni y. Gu 1990; 31: 1341-4. 6 O'Mahony S, A anz E, Ba on JR, Fe guson A. Dissocia ion be ween sys emic and mucosal humo al immune esponses in coeliac disease. Gu 1991; 32: 29-35. 7 Fe guson A, Mu ay D. Quan i a ion o in aepi helial lym- phocy es in human jejunum. Gu 1971; 12: 988-94. 8 Pe e son WJ. Immuni y, age and loss o immunohomeos asis. Ge on ology 1984; 3: 259-69. 9 An onaci S, Ji illo E, Bonomo L. Immuno egula ion in aging. Diagn Clin Immunol 1987; 5: 55-61. 10 B ill S, Kukulansky T, Tal E, Abel L, Polgin Y, Dassa C, e al. Indi idual changes in T lymphocy e pa ame e s o old human subjec s. MechAgeingDe 1987; 40: 71-9. 11 Nagel JE, Chop a RK, Powe s DC, Adle WH. E ec o age on he human high a ini y IL-2 ecep o o PHA-s imula ed pe iphe al blood lymphocy es. Clin Exp Immunol 1989; 75: 286-91. 12 Felse JM, Ra MJ. In ec ious diseases and aging: immuno- logic pe spec i es. JAm Ge ia Soc 1983; 31: 802-7. 13 Hiiimans W, RadI J, Bo azzo GF, Doniach D. Au oan i- bodies in highly aged humans. Mech Ageing De 1984; 26: 83-9. 14 Sal zman RL, Pe e son PK. Immunode iciency o he elde ly. Re In ec Dis 1987; 9: 1127-39. 15 Goidl EA, Choy JW, Gibbons JJ, Weksle ME, Tho becke GJ, Siskind GW. P oduc ion o au o-an iidio ypic an ibody du ing he no mal immune esponse. VIII. Analysis o he cellula basis o he inc eased au o-an iidio ype an ibody p oduc ion in aged mice. J Exp Med 1983; 157: 1635-45. 16 Buckley CE, Buckley EG, Do sey FC. Longi udinal changes in se um immunoglobulin le els in olde humans. P oc Soc Exp Biol Med 1974; 33: 2036-9. 17 Finkels ein MS, Tanne M, F eedman ML. Sali a y and se um IgA le els in a ge ia ic ou pa ien popula ion. J Clin Immunol 1984; 4: 85-91. 18 B and zaeg P. Human sec e o y immunoglobulins-VII. Con- cen a ions o pa o id IgA and o he sec e o y p o eins in ela ion o he a e o low and du a ion o sec e o y s imulus. A ch O al Biol 1971; 16: 1295-310. 19 Ganguly R. O opha yngeal ac hos de enses in aging. In: Pa B. Mes ecky J, McGhee JR, Bienens ock J, Og a PL, eds. Recen ad ances in mucosal immunology. New Yo k: Plenum P ess. 1987: 1409-16. 20 Ho an MA, Fox RA. Ageing and he immune esponse - a uni ying hypo hesis? MechAgeingDe 1984; 26: 165-81. 21 Sco H, Rognum TO, Mid ed T, B and zaeg P. Age- ela ed changes o human se um an ibodies o die a y and colonic bac e ial an igens measu ed by an enzyme-linked immuno- so ben assay. Ac a Pa h Mic obiol Immunol Scand. [C]. 1985; 93:65-70. 22 Phai JP, Hsu CS, Hsu YL. Ageing and in ec ion. In: CIBA Founda ion Symposium, 1988; 134: 143-59. 23 Pe e son WJ. Immuni y, age and loss o immunohomeos asis. Ge on ology 1984; 3: 259-69. 24 Co azza GR, F azzoni M, Ga o MRA, Gasba ini G. Ageing and small-bowel mucosa: a mo phome ic s udy. Ge on ology 1986; 32: 60-5. 25 B and zaeg P, Sollid LM, Th ane PS, K ale D, Bje ke K, Sco H, e al. Lymphoepi helial in e ac ions in he mucosal immune sys em. Gu 1988; 29: i 116-30. on Augus 23, 2020 by gues . P o ec ed by copy igh .h p://gu .bmj.com/Gu : i s published as 10.1136/gu .33.7.882 on 1 July 1992. Downloaded om