Fe-receptor tnediated clearance of immune complex-like material in Crohn ' s disease patients with elevated liver enzymes

The reticuloendothelial system of patients with ulcerative colitis 
and associated liver disease is impaired in its ability to clear immune complex-like 
material from the systemic circulation. The purpose of the present study was to 
determine whether patients with Crohn's disease and associated liver enzyme abnormalities manifest the same reticuloendothelial system clearance defect. Autologous 
red cells were radiolabelled with 51Cr and sensitized with anti-Rh(D) immunoglobulin 
G in vitro. After intravenous infusion of the labelled antibody-coated red cells, 
the radioactivity content of timed blood specimens was measured. The time required 
by the reticuloendmhclial system to clear one-half the labelled cells from the circulation (T1/2) was then determined. The T1/2 clearance times in nine Crohn's disease 
patients with elevated scrum liver enzyme levels (59.7

A LTHOllGH HEPATOBILIARY DlSEASE is a well recognized complication of both idmpathic ulcerative colitis and Crohn's disease, imrortant d ifferences exist in the mcidence and rype of liver d isease associated with these two diS<lt• ders ( I-3) .In rarticular.biochemical cndence of ch ron ic liver d isease is found m 8 to 50% of ulcerative colitis patients (4• 7).while only 4''., of Croh n's diM?a'-C patients have persistent elevations of their serum liver enzyme levels ( Ul Moreover, in ulcerative colitis, primary sclerosing cholangitis is the most com• mon associated hepatic disorder ( 2,8-LO), while in Crohn's disease, hepatic stcat• osis and gra n ulomas are more often found ( I I ).These findings suggest that the hepatobiliary com pl ications of ulcer• ative colitis and Croh n's disease may be caused hy different parhogeneuc mechanisms.
Recen tly.11 was reported that paucnt, with ulcerative colitis and ch ron ic liver disease have an impaired ability to clear immune complex-like material from the systemic circulation ( 12 ).This d efect did nor exist in patients with ulcerative colitis alone or patie nts with clearly defined liver disease of other etiologies.On the bas is of these and other investigators' findings (13.14), it was proposed that immune complexes could play an important role in the pathogenesis of the liver disease associated ulcerative colitis.The present study aimed to dete rmine if the same clearance defect exists in Crohn's disease patie nts with o r without associated liver d iscasc.

MATERIALS AN D METHODS
Study po pula tio n s : Four groups of individuals were studied: 12 healthy volunteers; nine patients with Crohn's disease only.ie, normal liver enzyme levels on two separate occasions at least o ne month apart; nine patients with Crohn's disease and persistent elevations of liver enzyme levefs (mninotransferases 2 or more times normal or a lkaline phosphatase and gamma glutamyltransfcrasc I .5 or more times normal) o n two separate occasio.,sat least one mo nth apart; and 12 patients with various other fr1rm s of liver disease including alcoholic liver disease (n = 6).chronic vira l hepatitis (n = 2).commo n bile duct stricture (n = I).choledochal and intrahepatic lithiasis (n = I).hemochromatosis (n -I) and drug-induced cholesrntic jaundice (n = I).Crohn's disense pmienrs wirh or without liver enzyme a bnormalities were identified by re trospective ch art review.
A ca reful hi story, physical exami n ation and the ap propriate laboratory tests were perfo rmed on ;ill patie n ts with Crohn's and liver di sc;isc to exclude readily idcntifiahlc causes ofliver disease.including alcohol.drugs.viral infection and mernbol ic disorders.Bec;i use live r enzyme levels were only mildly elevated, invasive procedu res such as percutaneous liver biopsy or endoscopic retrogrndc cholangiography were not performed and thus the exact na ture of the liver disease in these patients wa s unknown .
Three of nine Crohn's and liver disease patients had complaints consistent with cxtrainccstinal C ro hn's Jiseasc !arth ritis in a ll three), as compared to (our of nine patients with Crohn's dis-  ease alone ( 'i to 20 prcdniso ne equ iv;ilencs).One p;i tient in each group was a lso taking mctronidazolc.Written, informed co nsen t was obtained from all study participants.The study w;is approved by the Univl'rsity of Calgary and Foo thill s Hospita l Ethics Co mmittee a nd Radi nrio n Safoty Committee at the University o f C:i lgn ry.C li ni cal a n d la b o r ato r y investiga• tion s : All p:irticir:inrs h;id blood drawn for thl' following laboratory tests: sc rum asparmte aminotransferase; ;il:,nine aminotransferase; alk:i linc phosphmase; and gamma glutamvltransfcrn~e In addition.sera were tested for lgA.lgG and lgM level~ as well a~ ~crum C 1 :ind C 4 levels.The~e in vestigatio ns were performed hy hospirnl clinical laboratories usi ng srnnd;ird lahora to ry techniq ues.Sera were screened for immune complex-like ;icri viry hy solid ph;isc enzymc-lmked 1m munonss.iysfor both lgG and lgM complexes !15) I mmu n e comple x c learance by the r etic ul oend oth c lial system: Erythrocyte cleara nce studies were carried out on all Rh(D) positive patients ;is previously described ( 16,17).In brief.autologous e rythrocytes were isolated from whole blood.washed three times in ice cold physiologic sa line and resuspended ro:, concentration adjusted photomcrrica lly to 6.6 x I 0 8 cdls/m L. The cell s were la belled with steril e ; I C r (Na 2 ; tCrO 10 µCi/ml, Amersham -Se;irle Corporation.Arlington Heights, II), waslwd fou r times in physiologic sa line.then resuspended to a concentration of 3. following which the lgG sensitized ' 1 Crlabelled e ryth rocytes we re w,ished twice and resuspended in p hysio logic saline An ;iliquot of cells (contnin ing app roximately 250,00() cou n ts/min) w;is then injected through an anrecubical vein.rind eryrhrocyrc surviv;il rnlcul;ired from the radioactivity m blond samples obtained at 5. 10. 30,60.90and120mins(AUC Trapezoid a l Rult' .Ti 59), as recommended hy tht' In terna tional Committee for Swnd;irdiw1ic1n in H;icmmology 11 H).In no rnsc was n clearnncc study followed hy any un1nward effect Defi nitions and statistical tec hniques: The hall-life of tlw radiochromnted cells is the time :it which 50''., of thl' labelled cells lrns bt'cn removed from the circulation A Student's 1 test and Fisher's ex:1n test were used for determining differences hct ween grnu ps of p:111ents :in d controls.Onlv P vnlues less th;in 0.05 were con-,idered significant        of the three Crohn's and lt,cr disease patients with arrhnns nnd th rCL' of the fourCrohn':, disease p,tucnt~" ith archnns and/or inti~ T here was no , 1gnif1canc difference hccwccn mean clearance nmcs for 1hmc taking corticostcrrnds versus those not on cort1cmtero1ds ( 'iZ.I • 5 L) versus 58.I L , 9 mins, rcspcni\'l'ly)

Vol. 1
No. I. October 1987 Fe-receptor clearances 1 n Crohn's 3 x I 0 8 cclls/mL.An aliquo1 o f the cells was then sensiti,L'd by the add ition of lgG anti-Rh( D) (0.4 µg/mL.WinRho.Winnipeg.Mani toba) sufficie nt, nccording to p reliminary experiments, to result in the binding of a pprox imately 1000 molecu les of lgG per erythrocyte.The same lot of ;inti-Rh( D), contai ni ng noncomplemen t fixing lgG, was used for all experiments.The eryth rocytc-lgG mixture was incubated at 37°C for 30 mins.

9 )
tivity was higher in !iv e r disease patients when compared to Crohn's disease (P < 0.05) and Crohn' sand liver disease patients (P < 0.05) but not statistically d iffcrcnt from hc::ilthy vol untcers(P = 0.06).The results of lgG-tagged erythrocyte clearance studies arcs hown in FigureI.All patients had norm al clearance curves when compared to he al thy controls.

Figure 2
provides t he results of compurer generated half-lives in individual patients.The mean + S EM half-life for healthy volunteers wa s 49. 1 ± 3.1 mins, as compared to 50 .7 ± 4.

TABLE 1 Patient
to three of nine with Cro hn 's dis-