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False positive anti-hepatitis A virus lgM result in a patient with autoimmune hepatitis

Jt\~1E" R GRAY. MD. LRs P. ST! l~EIRECHER ~10

ABSTRACT: This report describes a patient with autoimmune hepatitis in who m a posi .vc test result for hepatitis A virus (H AV) IgM an tibody led to diagnostic confusion until it was shown to be false positive by immuno precipitation of IgG from serum. The mechanism for the fa lse positive result may have been related to marked hypergammaglobulinemia, as scrum obtained after normalization of im­munoglobulin levels tested negative. However, several oche r mechanisms were also considered. This case illustrates that the possibility of false positive results with the anti-HAV lgM assay should be kept in mind when the clinical fea tures of the illness are not suggestive of acute hepatitis A. Can J G astroenterol 1989; 3(3):115-118

Key Words: Autoimmune hepatitis, Chronic active hepatitis, Hepatitis A IgM sero­logic tests

Resultat faux positif d 'anti-HAV dans les lgM seriques d'un patient atteint d 'hepatite autoimmune

RESUME: Ce rapport decrit le cas d 'un patient atteint d 'hepatite autoimmune pour qui le test a donne un rcsultat positif d 'anri-HAV dans lcs lgM. Ceci a en­rraine une confusion dans le d iagnostic jusqu'a ce que l'on dcco uvre quc le resul­tat en question eta it du a l'immunoprecipitation des lgG seriques. Le mecanismc cxpliquant cc resultat faux positif est peut-erre relie a une hypergammaglobuli­nemie marquee, le serum obtenu apres la normaliiation des niveaux d'immuno­globulines ayant donne un resultat negatif; plusieurs autres mecan ismes ont mutefois ere etudies. Ce cas d emon tre q ue la possibili te des rcsultats fa ux positifs portant sur les anti-HAV doit ctre contemplee quand Jes signes cliniques de la maladie n 'ind iq uent pas une hepame A aiguc.

D1m1o11 of Gmtrocnrcroloi:~ Dc1>arnnenr of Mcd1c111e L"ni1-ernty of Bnmh Col11111b1a. \'ancomer, Brn11h Columbw

Corre1/1011dc,1ce and re/mnr1 Dr Ur.< P Srcm/,recher. Department of Mcd1c111c. D1tmon of Gastrocntcrolo1;y l'n1t·er.1m oj Br,mh Colmnb,a 2211 ll'c"i/,rook Mall. \ e1nco111cr. Br111ih Co/umbra \ ' 6T l\\"i Telephonc(6Q4J 22R-r727

Recm•ed fnr pu/,/,wuon A11J!11Sr 23. /Q8B. Ac,c"/>tcd Dc,cm/,cr /'l. N88

CA~ j 0ASTROENTEROL VOL 3 No 3 )L':-F 1989

T H~ \10'1 \\ J[)H) l 'SED "ltRODIAl

nosuc tests for acute hepa titis A virus ( HAV I mkction in\'olve immuno­assays for HAV specific lgM ( 1.2) Com­merc1nlly ava ilable test ki ts nre sensitive ,olid phase lgM capture as,ays w1th rad101mmunometr1..: or en:yme im­munomemc detection and quan11tat111n ( 3) T here ha\ e hecn wry tt'\' rL'por tcd false positive re~u lts and the spL'C1firny of a posni\·e an t1-HAV lg~1 result 1s, therefore. assumed to he high (4) This report describes a pancnt with symptoms suggest1ng hepanns, m whom an unl'X peered positive ant1-HAV lgM result led to diagnostic conf us10n un til 1c \\'as dem onstratcd to he a false pos1m·e result due to interferi ng lgG in the plasma The fol­lowing case 1s the fi rst publ ished report of a false pos1 ti\'C ant1-HAV lgM enzyme immunoassay result and should alert cli­nicians to this poss1b1licy when unex­pected positive anri-HAV lgM results a rc encountered

CASE PRESENTATION A 70-ycar-old caucas1an woman prL'

sented wi th a six week history of fauguc, malatse and anorexia. Ocher than some mode rate cxcrrional dyspnca of six mon ths duraunn , 1hl' patien t had pre-

11 5

GRAY AN[) SlrlNllRFCI IFR

\'iously been in good health There was no pnor history ol jaundiCL' or liver dis­ease. Thl' patiL'n t had never received hlood products and reported no contact with Jmmdiced individuals, alcohol or exposure co potcnually hepatotoxic drugs. lniual physical examination showed mild ictcrus, multiple spidn angiomas and dry rates at bmh lung bases. The liver was norm,11 in stZL' with a somewhat hlunt edge bur 11() noJu­larity. There was 111• splenomegaly or ascircs.

AST (IU/L)

prednisone

globulin • albumin •

(g/L)

1000

BOO

600

400

200

0

BO

60

40

20

0

•

0 2 3 4 5 6

months

Prcst·nting laboratory observations were: bilirubin 44 ~111101/L; aspartate aminotransferase 500 iu/L; alkaline phos­phatase 160 iu/L: albumin 23 g/L; glob­ulin 63 g/L; prothrombin time 14 s, an­tinuclear antibody positive to I :8() di­lution; positive antismooth muscle anti­body; and negative hl'pat1t1s B surface antigen ( HBsAg) and anti-HBc. A chest x-ray revealed a diffuse (me reticulon­odular infiltrate. Pulmonary function tests demonstrated a decreased total lung capacity, normal flow rates and normal diffusing capacity. A liver biopsy showed expansion of the portal tracts with a heavy infiftrate of lymphocytes and plas­ma cells, piecemeal necrosis and focal lobular inflammation and disarray (Fig­ure I ). On the basis of these clinical and pathologic findings a diagnosis of auto-

Figure 2) Et'olu11cm of /,i()(:hem,ca/ w.1r 1·c~1dc.1 trnh rrcaoncnr

immune chronic hepatitis with associ­ated interstitial lung disease was made.

Prednisone was started at an initial dose of 30 mg/ day and there was a

F igure I ) L1wr /)1(1/hY ,lwmn~ cx/imi;1011 o/ rhc Jiorwl cram 1.l'llh a hcm·y 1njil1ra1e of lymphocyre., and /1h1mw ccl/.s, /nccemeal nc,rn.11.1 ,01cl Ji,wl lobular 1n/lammarron anJ J11arrny Hcmuroxylm ,mJ CO.\ln f X 225)

116

prompt symptomatic and biochemical improvement. Two weeks after the start of corticosteroid therapy, a positive anti­HAY lgM result was received (HAYAB­M, Abbott Laboratories, North Chicago, IL) and was subsequently confirmed on two repeat determinations over a per­iod of four months. Corticosteroids were discontinued and over the next few weeks the patient noted recurrence of anorexia and fatigue; transaminascs also increased somewhat (Figure 2).

The virology department of the British Columbia Provincial Laboratory of Puh­lic Health was contacted and was asked to examine the patient's sera for factors that might have caused a fa lse positive result Three separate scrum samples drawn over a period of four months gave spec­trophotometer absorbancc values about twice that of the cutoff value (serum 0.167, cutoff 0.074). A lthough unques­tionably abnormal, the values were con­siderably lower than those usually seen in patients with acute hepatitis A. When the assay wa5 done without HAY anti­gen in the reaction sequence, the result, were negative. All scrum samples were

CANJG>\SJRmNIIROL V()I 'INo'l ] lJNI 198Q

retestl'd aflt·r add111on pf slwel' ,int1hu·

man lgG ( Rr Absorbent. lkhrmg. M.1r­burg, \\c;.t Germany) and tht· rt·,ults

were thl'n f1>u nJ to he nq,:;11 ive

lmmun11suppress1,·e 1hcrapy \\'ils re· sumed wnh prl'dnis11ne 10 mg/day and azath1opr111t· 50 mg/lL1y and all symp

toms and h10..:hem1ral ah1H>rm,1litit·,

res<>kl'd m·L•r the nt·xt fl'w nwnth,

DISCUSSION Although anu-HA \ lgM 1s L'' 1dt·nth

;1 sensitive .md fairly spcuh( Jiagnm,tlL

tcsc. there 1s llllL' prt·,·1ous report of fabt·

positive anti HAY lgM n'stilts using a radm11nmunllas,,ay nwthod 15) In that

report, six p,111c111, \\'ilh rcmlltt' ,lLUtL'

herat1t1;. A \\'l're found tl> ha\'l' pcr;.1s·

tcntly posttl\l' tesis for anu-HAV lgM.

thought to hl' dut' to HA\' spt·nfiL lgA wtth rheumatoid f,1Ltrir ,llllVity In thl'

prc:;cnrrast•, rl'nwv,11 l,f lgC from park•nt

-erum ,,·1th mono;.pcril1t prcnp1tat1ng

,mribody aholisl1l'd tlw rl'artivtty, indi· caung that the pns1tl\'l' resttlt \\;i, not fg}.1

specific and hL'nn• was folsl' po;.111ve

The hesr cnmnwrc1ally .1, ailahlL· as-,avs

foranti HAV lgM ,lrl' lgM L·np1t1rc solid

phase r:idiotmmunoass,1\' or t·n:ymt•

immunoassay Thl' dt·s1gn of thesl' ,1ssays

mvolws matrix heads ..:oatcd with anti·

body to human lgM fest serum is

added and ,tny lgM e0t11ained 111 it is

hound 10 tht· heads Unbound serum

components arc rL'moved by washing

and HAV anttgen 1s then added If lgM

anti-HAY 1s prcsen l, thl' adtkd HA V

anttgen will be hound to the lx·ad hy

thi~ :inuhndy AmiboJy to HAV whic:h

has heen rad101odinatL•d or roupkd Ill

horseradish pl'rox1dasl' t~ thl'n added and its binding will hL· 111 i:miportil\11 co tht·

amount of HAV an1igl'n hound Tht·

beads arc then assayeJ for ra<lt<>artivtty

(radio11nmunLK1$,ay), L>r ..:ulour devdnr·

ment after add11ion nf o-phenylencJi;i

ACI<NOWLEDGEMENTS: llw ,lllthor, thank Dr 11 ls.uhin,k1 for rl'krnng thl' pattl'nt aml Dr P J M1ddll'ton t.,r r<·rt',,rmmg till' ,,:n, diag11<1,11, 1,·,ts h1r HA\

REFERENCES Ll'111<1n ~M Typ, A\ 1r.1l lwpat111, N h1gl I Ml·J 1%'i. ll l Il1'ill (,7 D11'n'iag JI \\and, IR 1-:,,tt' RS Ann,· hepat1t1, In Braunwald I·, l"elhadll'r

mtnt' ;md hydrogen pl'rox1de (cn.:yme

1mmuno,1ssa\ l to quantify antihndy bmding

Onl' wdl known cause of false po,i­

tl\L' results \\'ith sl'rodtagnostll tc,ts for

pathogen specific lgM 1s rheumatoid fac­

tor ,1Lt1, tt\ 111 pam:nt serum 16.7) Rheu­

matoid factor~ arL' lgM a1111hodtt'' Ji­n< tl'd ,tg,unst l1llmologou;. lgG They are

nf 11b,·1ou, 1mpnrtalK<' tn rheumatrnd

,trthnn, and ean .il,o hl' assnrtatL'J ,vtth

l>thl'r ,y,t<'llllC i111lam111m,1ry 11r mll'Ltious

LL1ndit1t>th as ,wll a, <>L'Casionally hetng

pt L',cnt 111 hl'a!th\ normal suhJt'Ch. lt has

hLTn found tha1 l'\'l'I\ \'l'ry low COIKL'll· tr,111ons of rhl'Ul11,ttl,1d t,1..:t,>r L' iln inter·

krl' with 1mmunoassavs and tn ,urh

rasl', tlw rdatiH·I, msL'thltl\'L' latl'x agglu­

un,1111111 ll'sts Im rlwumat<>id f.Ktllr that

arl' 1n r<>utinc u,l' t1,n·,aluat1<111,1l rheu· m;1t1r di,11rdn, may yield nL'J!illl\T r,·sulrs

((1,7). Tlw pn,hll'm pf rheu111a1111d I.iv

tm 111tl'rft·rem1 can lw rcduc,·d hy rl'·

mP\'tng rlwum,1to1d f,tllor h\ prL'(1p1ra-11011 tl'Lhn1quc, 111,tLt1,·,mu11,1! rlwumil·

to1d facu ,r hv heat111g 11r diluting tl'st st·1;1

In the prL'st•n1 t,lsL', rlwumilt,11d latt\lr

\\'.ts neg.1t1,·e a, nll'asured by a l,1lt'X

aggluttn,tt1on ,lidl' rest tOnho Philrma

ct•utirals Lid. Don Mills, Ontanll) hut

<>nlv scrum s;11npk•s oht,llnl'd aftn thl'

inittation of tmmunosupprl'ss1,·e tlwrapy

wl'rl' assawd and h1ghl~ scn,uiw t n ynw

immunllassay or radioimmunoassay test"

f111 rheumatoid !actor \\'ere not Jo1w

One t,1n ctn j,.,1on l\\'O mechanisms

wlwrL'hy rhl'umato1d (actor might lllll'r·

!ere wtth the anu-HA \' lgM ,hsa~ fhc fir;.1 1s a, 1rus anttgen indepe11dc111 false

pos1tiYL·. \\'herl' tlw lgM rheumatoid fav

tor binds tn the anti lgM .::m1pkd to thL'

hl'ad main, and ,, lwn lalwlk·d anti

HA \I lg(, ts .1ddeJ. n 1s h11und by thl'

rheumatoid fol tor l'\'l n though thl'rL' ts no HA\ ,1nttgt·n btiLmd to clw ma111x

Thl' seu ,nd type of falsL' pos1ttve ts anti·

Kl f\•1, r,J.,rf RC, , \\'11',,11 J[) M.1rtm JB. hlllll A~. t:,k H,,rrtson, Prmupk·, of lnt,•1 nal Ml'd1cml' Nl'w York · ~k(,r;m Hill. lll~7 I \Z'i '\:-. Dl'ck,·r R/\1 1'.u,akow,kt "M \,mdl'rhdt A', ,·1 al L )1.1g110,ts nf ,t,Llll.' hq:i.11111, A bv HA\'AB-1'1.\, ,t d1rt:ct rad11H111mum1;1ssay for lgM .11111 HAV Am I Cl111 Pathnl 1%1 i6: 140·7

4 Swr,h (iA , Bmli,ky (. Parker 1\1 , ,·1.,f l l,c of n>ll\'l'l\li,111al ,111d lgM 'J'l'l'ill,

Folse pos1t1ve ontl-HAV lgM results

gen dt·1wntk111 and rL•quires .11111 -HA \ [g(, 111 the te,t serum Thl' r<,nJugatton

st'(]Ltl'l1Ct' hl're ts matrt\ (anu lgM)

rheumiltrnd t;irtor antt HA\ lg(,

HAV antigen - alll1-HA\ lg(; lpl'roxi

dasl' l,1helkd) This typl' <'f mr,·rkrl'l1cl'

is hdtl'ved to require rel,1t1wly high k, · els o( rlwum,1toid f.1r.:1or ( H)

An alternauvt' l'xplanat1on that \\'ould

not tnvokl' rheum;itotd tm tor might s1m·

pl, lw tncrt•asl'd nonspl'rifi, ad,orptllll\

ot'HAVan11gen to thl' lwadsasa ronsL'

quenre of markl'd hyperglobul11wm1.1111 the tl'st st'rum Thb appt',irs 10 hl' .111

attraruve explana1ion for the rl'sults in

the present c;i,c a, the p.111,·nt w,1s mark­

edly hyperglobul111emir at prest•ntarion

and, \\'hen the 1mmunoglnhul111 k·,·cls

had norm,il1zed afler se,'l'ral tnllnths llf

1mmunnsuppress1\'l' trentmt·rtr rlw ;inri·

I IA\ lgM tesr re,uh hl'rame negattn' .

hirthl'rnH>re. thl' Im~ kn·l of ro,111, 11\

1, what would hL· t·xper1ed 111 a situation

\\lll'rt' high ' hac-kgmund' rathl'r than , 1rus spl'c1ltc antibody was m,·okl'd .

Sumlar falsl' po;.tti\'C results h,1\'l' hee11 dt·scnlwd tn <>tht·r ,·1rus spl•cinc lg~1 antt

hodv assay, 111cluding those for rubdl.1 tox1,plasr11osi, and cytt1megal11\'1rus, and

tlw frequency pf such fobc pm1t1,·,·

rl'sults m.t\ n·ach I.~ H''. 11f pattt·nt sam·

pies tl'sted 16,l'l). lt "'perh.tps surprising th,1t then· 1s apparentlv only tll1t' pn•v1·

ou, rq,on of this prob km in t ht· anti• HAV lgM ,1s,ay ( 5 ). ThL pn:st·nt casl'

11lu,1ratl's 1he tmportancl' of considl'nng

the possihility of false positi\'l· results

wuh 1his ,1ssay when clin1rnl features of the dliwss arc not in ket·ping with acutl'

HA\' mfettl<>n As well reports of pt:r· s1stt•nct' o( ant1-HAV lgM for sl'ver:1 1

vcars after ilLUte inft-cttons (l)) or dl'scnr

t1ons of\musual' prescntatton o( hl'pa

ttt1s A ( 10) need rn he mtnprl'tl'd with

ronsidl'ratton gi\'l'n to possthle folsc pl>s·

it1Vl' .111ti-HAV lgM test rt•sults

r;1din1111111unoa"ay, for ;mti-hcpa11t1, A ,rnt1hody 111 .rn <1t11hrl'ak of h.:p,llllh A Am J t-..frd 1982 7 l ho H,

'i Bmt·n, 1'1R Pi,·m,h<m1 CiR, H.,rnl' tl OB 1-alsl' pmHt\'l' r.:,ult, nccurring 111 ,, r.1d1rn11111nml1a--.ay tor lwr.11111, A .111rih,,J, t,u dw lc!',.1 das-. J \'1rol 1\frrhod, lll8 U 287-95

(, ~kurm,lll O P,•tn lll>ll <>I ,11111\'tr,il fctl.1 ,llltihnJ1l'' ,tlld 1h pr,,hlc,n, A rl'\'tl'\\ In · Rad1111~n PA ,•J Current fop1c, in

117

GRAY AND STEINBRECHER

1'11cn,b1olugy ,\llJ lmm11nology Nl'w York Srnngl'r \'erlag, 19~ 3.104 101 31

7 S.tlnncn E:·1'1. Vahen A. Sum I. \\',11:cr 0 Rlwumnro1d t:ict<,r m ,KUil' v1r.1I 111fl'cuons ln1erkn,ncl' with dctl'rmin· aunn of lgM li:G :ind lgA ant1hod1cs 111

.111 l'n:yml' 1mmunn,1",l\' 1 lnled D1,

1480; 14l.l 5l)-5 H 1'.ll'urman OH l1nla BR lgM-clas,

rhcumaw1J faunr mterfl'rl•ncc 111 thl' solid phasL r.1d1111mmunoas,ay of rulwlla-spcc1flc lgM anubodics J Clm Pacho! ll)7~. 31 4H \. 7.

9 Kao H\\'. Ashl·,1va1 M. Rl·dckcr AG Thl·

pt'rs1stt'llCL' of hcp,11111s A lgM an11b0Jv ,lfrl'r allltl' clm1cal hcpauus A Hcpatol,,g) 1%4.4 9 H-b.

111 Gordon SC. Reddy 1-:R. '>chill l, Schiff ER Prnlonged i111ri1lwpat1c d1olestas1s sl'cnnd.ir1 t<' act11c ht·pauus A t\1111 lntl'rn Ml'd 1%4. llil 6 35 7

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