Absence of peripheral microchimerism following HLA-or non-HLA-sharing pretransplantation blood transfusions

164

Abstracts

P888 MlIC-RESTRICTED ALLOREACfIVlTY TRANSPlANT AnON

AND TOLERANCE

IN

HEART

P889 ANALYSIS OF MICROCHIMERISM BY NESTED PeR-SS P OF !!LA-DR lI.'1D - OJ IIJCI IN RENAL TRANSPLlINJ' REl:IPIENrS

Martinetti Miryarn, Daiellt Cristina. Gatti Cristina, AmbroseJli f ranco, Arbusuni Eloisa's> Poli F~ncesca n: , Salvancschi Laura. Servizio eli Immunocmatologia e Trasfusione and - Istnuio di Anaiomia Patologica, IRCCS. SMatteo,Pavia.ltaly: ··Scrvizio di Immunologia dei Trapianli, IRCCS

Turakainen Hilkka , salmela Kai ja ,Ahone n J uha ni, Koskimies saija Finnish Red Cros s Slood Trans fus ion SeJ:Vi c e , Hel sinki , Finland Unive rs i t y Centr a l Hospi t a l ,He l sinki, Finland

Pohclinico, Milano,lral)

A group of 37 I:.6T-treat ed rena l transplant pa t ient s receiving a kidney fran related donor with one hap l otype nusrratch was studi ed .Innor and r eci pi ent HLA- DRB I and - rQBl genot ypes were de termined fran ~ extr a c t ed f ran t he pe ri phe ral b l ood . Nes ted PCR-SSP was used to determine the pres ence or absen ce o f the donor DRBl and/ or OJBl alleles in the r c i pi en t -s sa:npl e o Firs t, a pair of primers was us ed t o ~lify the exon 2 of llRIl and OJB genes .A small crrount of the r esult ing PeR product was us ed in t he second round of ~lif iCdtion which ffilPl oyed pr imer s e t s designed to ~plify the desired alle l e. Nes ted PeR was a t least 1000-fold rrore s e nsitive than s t an dard PCR-SSP allowing the d etect eion of 1 donor cell in 100 000 recip ient cells .

TheHLA-DRB1 , DRBJ, DRB4, DRB5, DQAI, DQSI and DPBI polymorphisrnshave been defined by molecular techniques (PCR-SSP and reverse PCR-SSO) in 67 heart trans planted patients. The outcome has been eva luated by mult iple endomyoca rdia l biopsiesand graded as follows : group I wi th absent histolngical ~ecrion ( 10patients). group 2 with mild (35 patients) and group 3 with moderate rejection (22 patients). Either protective and intolerant alleles have been idcnt itled, the former being HLADRBlo04 (with a frequency of 25.0%, 6.1% and 5.6% in the group I, 2 and 3 respecuveiy; p=0.024), DRB4°0101 (45.0%. 18.2%, 19.4%; jR).037) and DQAl o0301 ( 25 .0o/~ 7.10/., 4.5%; p=O.022), the latt er being IU.A-DQAI*0501 (15.0%, 25.7%, 43.2%: p=O.04O). At the sequence level, it seems 10 be relevant the DQA1° aa.34 position: wben negatively charged (glutamic acid) it correlates with tolerance (65.0%, 35.7%. 36.4% (>-0 .05). The GGPM sequence in the f hypervariable region of DPBl antigen binding cleft. aa84·87, also seems to have a protective role: its frequency raised to 80.0% in the cases with no rejection , 67.1% in mild histological rejection and 56.8% in moderateone (p- n.s.). The combined analysis of all the HLADRB,DQAl,DQBI and DPBI toleranr sequences discriminated significantly the patients(77.8%. 50"10 and 22.2% in the three groups respectively; p=O.OO97).

The mean t ime span fran the t r ansplant was 5 . Byrs ( l - l 2yr s). microchim2r ism was de t e cted in half of t he patien ts. The presence of c hime r i sm was canpered to t he s igns o f acute or chroni c r eje ctions, time s pan fran the t ransplant. functioni ng capacity of t he transplant a nd the characteristics of the donor.

P890

P891

A DETRIMENTAL EFFECT ON GRAFT SURVIVAL OF HLA-B44 AND OF HOMOZYGOUS HLA·DR ALLELES IN DONOR CORNEAS

PO SITIVE C ROSS M AT CHES OUTCOM E

Pauline C. Creemers and John C. Hill Prov. Lab. Tissue Immunology and Dept.Ophthalmology , University of Cape Town, South Africa We analyzed the effect of matching for individual HLA-B and HLA-DR ailieles on the incidence of the first rejection episode (RE) and graft failure (GF) in 99 corneal recipients. No effect of matching for any specific HLA-DR allele, and for matching of HLA-B7, -B8, or -B70 was observed. However, RE and GF were increased in recipients matched for B44 (RE: P=O.0119; GF:P=0.0547). A detrimental effect was also evidenl when only the donor comea carried the 844 allele ' no such effect was found for recipients. When the group matched for B44 and the group carrying B44 on the donor cornea were combined results were highly significant (RE: P=O.OO78; GF: P=0.0061). Relative risk was 2.18 for RE and 3.62 for GF. We also noted a detrimental effect when the recipient and the donor were mismatched for the DR allele, and the donor was homozygous (RE: P=O.0723; GF: P=0.00(0). When the results were re-analyzed after removing all donors carrying B44 from the study group, the effect was diminished 'CRE:P=0.1665; GF:P=O.0530). Relative risk was 1,73 for RE and 3.04 for GF. These findings may be clinically relevant and should be confirmed in a larger stUdy group .

P892

ISTHEIMMUl'OMODULA11NG EFFEcr OF lILA-DR ORHAPLOTYPE SHARED BLOOD TRANSFUSION DEPENDENT ON TIlE COMPOSmON OF THE TRANSFUSATE ? Barbara van der Mas!, HenkVietor. EllenvanderMeer-Prins, Simcoe van B"". Peter van den Bsen & Frans Claas. Dept.ofImmunoltematology & BloodBank, Leiden, TheNetherlands. !'retransplant blood cransfusilll1S (BT)can havea favourable effect on transplant outcxme. Theinnmmdogical mechanism involvedis still unknown. Earlier it wasfound by Van Twuyver et al. (NEJM'91;325 :1210) that HLA·DR or haplotype shared transfusiClOS can lead to cytotoxic T cell non-responsiveness against donorcells, To investigate the effect ofHLA-cornpatibility between blooddonorandrecipient on T cell non=ponsiveness in our centre, we determined the frequency of cytotoxic T cell precurscn (C'I1.¢)specific roc donorcells before BT. at two weeks acd at morethaa 10 weeks aftorBT. These patientsbadreceived onetransfusionof erythrocyte coocentr3l< olwbich the bu1IYcoat was removed. EightpatientssharedonelILA-B + DR antigen, anaber 8 patients me HLA-DRantigen and 3 patientsnoHLAantigens withtheblood donor. Of six patientsthe T cellreceptor (TCR)V-beta family usagewas determined as well, AU patieotssbowed an increased CTLpf two weeks sfb:tr BT. No sigoificant devease was seenmorethan 10 weeks ~ BT compared to the CreqUeDC)' before BT. Noneollhe patients showed a deletion in theTCR. V-betafamilyrq>ertoire. In coatrast, after BTen
AND

LIVER TRA NSPLA NT

Parissiadis Anne t, Meyer Caroler, Simconi Urnbertos, Boudjerna Karirnz, Fischhach Michel'. Woehl-Jaegle Marie-Lorrainez, Wolf Philippez, Tongio Marie-MI 'Blood Transfusion Centre. Strasbourg, France, 2Transplant Unit, ,Ped ialric Unit, Hautepie rre Hospital. Strasbou rg, France Conflicting reports have been published on the effect of positive crossm atches on liver transplant ou tcome, We report the biological and clinical

da ta of 21 liver re cip ients transplanted in spite of a positive cross-match, in a series of 22U liver transplantations. Among these. 7 (33.3%) displayed specific antidonor HLA class I IgO antibodies (group I), 2 (9.5%) specific antidonor HLA class I and class II IgG antibodies (group 2),2 (9.5%) specific an tidonor HLA class II IgG antibodies (group 3) and 10 (47.7%) mill HLA-B Iymphocytmoxic IgM antibodies (group 4). All

patients were given the same i mmu noxuppressi ve therapy (CYA, steroids and A Z A) , except three who receiv ed additional ALG ( I case in each of groups 2, 3 and 4). Among patients with a positive B lymphocyte crossmatch of non HLA speci ficity, &()~, showed one or two acute rejection episodes. Nevertheless. all were still alive after I year. O nly 36% 01 patients with a positive cross-match due to specific HLA class I and/or class Il antibodies experienced a rejection episode, although 1&% had a non functional graft. The survival rate after one year was 82%. In conclusion, while the survival rate is slightly lower in patient, transplanted with an HLA positive cross-match, specific antidonor HLA antibodies are not an absolute contraindication for liver transplantati on.

P893

ABS E.'1CE OF PERIPHERAL MICROCHIMERISM FOLWWING lILA. ~ NON-lILA-SHARING PRETRANSPLANTATIO N BLOOD TRANSFUSION S.

Caillat-Zucman S. Benini V and GClF. INSERM U25. Hopital Necker. Paris, France Groupe Cooperatif de I'Ile-de-France The beneficial effect of pretran splantation blood transfusions is sti l controvers ial. The cellular mechanisms underlying immune toleranc remain elusive, although transfusions have been reported to be associate with reduced aIIoimmunization and better protection from acute a1logr rejection episodes. To investigate whether the development of a systemi micr ochimer ism foll owing transfusio n co uld acc ount for sue observations. the presence of peripheral donor-recipient microchimeris was investigated in two groups of hemod ialyzed patients given tw different pregrafting transfusion protocols. Patients received one unit 0 third-party whole blood without HLA -DR identity (group I, n=22) or wit one DR identity (group 2, n=19) as defined by a shared DRBI " allel following generic genotyp ing . Peripheral blood microcbimerism wa slUdi~ 1,4, 8 and !2 weeks after transfusion using sequence-specifi amplification (detection threshold 40 pg DNA corresponding to a I~ donor/recipient cell ratio). A transient microchimerism was oberved at and/or 4 weeks after transfusion in 8 patients (4 in each group ). an disappeared afterwards. These results do not support a major role for establishment of microchimerism in the induction of tolerance followin pregrafting transfusion. I