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For investigating the possible influence of maternal-fetal HLA compatibility on maternal microchimerism, DNA samples from blood of 120 maternal-fetal pairs were genotyped at two polymorphic loci: glutathione-S-transferase M1 (GSTM1) and angiotensin-converting enzyme (ACE). Informative pairs (mother heterozygous/fetus homozygous at one of the two loci) were then tested by quantitative real-time PCR for the noninherited maternal allele(s) and genotyped at the HLA-A, B, and C class I loci and/or at the DRB1 and/or DQB1 class II loci. Small numbers of maternal cells were detected in the circulation of 16 of the 30 informative second-and third-trimester fetuses. Comparison with HLA data suggested an association between microchimerism and maternal compatibility at the class II DRB1 and/or DQB1 HLA loci and with the maternal HLA-DQB1*0301 allele. There was no relationship between maternal microchimerism and maternal-fetal HLA compatibility at other HLA loci or with gestational age, fetal anomalies, or red cell or platelet isoimmunity. Transplacental passage of small numbers of maternal and fetal nucleated cells, including hematopoietic stem cells, is a common occurrence that often results in persistent fetal or maternal microchimerism-the presence of small numbers of fetal or maternal cells in mothers or their progeny, respectively (1-3). This raises the possibility that maternal and fetal microchimerism may play a role in such clinically important phenomena as immune ontogeny, vertical transmission of infections, and tissue repair and regeneration by transdifferentiated stem cells. Particular interest has focused on the possibility that chimeric maternal and fetal alloreactive lymphocytes may play a role in autoimmunity (4 -6). Although an increasing number of clinical studies have addressed this question, there has been a paucity of information concerning the factors that regulate the presence and levels of naturally occurring maternal and fetal chimeric cells.Among the possible regulatory factors that might be involved, maternal-fetal histocompatibility seems to be a prime candidate in view of the importance of histocompatibility in regulating hematopoietic chimerism in both adult and fetal recipients of adult bone marrow. In this study, we directly tested for the first time the influence of maternal-fetal histocompatibility and specific HLA alleles on both the presence and level of maternal microchimerism in the fetus. The results strongly suggest that maternal microchimerism in fetal blood is associated with maternal compatibility at the class II DRB1 and/or DQB1 HLA loci and is likely also associated with the maternal HLA-DQB1*0301 allele. METHODSStudy subjects. Paired whole-blood samples were obtained from 120 maternal-fetal pairs who underwent fetal blood sampling for a variety of medical indications, including red cell or platelet alloimmunization, and the need for rapid karyotyping mandated by an ultrasound diagnosis of fetal anomalies. The gestational age at fetal blood sampling ranged from 18.3 wk to 38 wk ...

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TI-~ ~r~vENOUS ADMINISTtLZxTION Of local anaesthet, tc drugs ,n chmcal medmme was mataated by Bmr m 1908 Holmes, 1 an Februat3t 1963, reported ,,tlnrty eases for wll~eh he employed a mo&:fieatmn of Bier s ve~ous anaesthesm The teehtuque has been readily adopted by the Anaesthetm team m the new Teadnng Hospatal an Lagos, where many patmnts appear ]l[or emergency treatment of lesmns of the extrem~tles The 514 patmnts m thJis series wexe anaesthetized dunng the eaght-month permd from April to December, 198a They were unpremedmated and unprepared an that food had poss~b]qy been eaten w~thm a short t-,me of anaval METHODS A sphygmomanometer cuff was apphed to the affdcted extremity of the recumbent pataent and the blood pressure was measure, prior to drainage of the extremity and again one minute after final release of the tourmquet For hand refections the anaesthetist had the choice of applying the cuff above or below the elbow A 20-e e syringe loaded with hgnoeame was attached to a needIe (SWG 22), whmh was introduced into a statable veto distal to the cuff After elevating the extremity for one minute to allow venous dramagej the cuff was inflated above the systohe pressure, the extrematy was returned to the honzontal positron, and the so]utlon of hgnoeame was administered m a single mjeetmn The surgeon then prepared the extremity and performed the necessary operatmn, the dressing was apphed, and the sphygmomanometer cuff was deflated Holmes and Baer preferred the Esmareh bandage for the exsangumatmn ot the extremity, but m the few eases m whmh at was used here, at afforded no pmtmular advantage over the method of grawtatmnal drainageThe eoneentratmn of hgnoeame used vaned between 0 5 and 2 0 per cent, wh~Ie the rejected volume ranged from 10 to 40 c e for the first 150 patmnts Then ~t was demded that a I per cent hgnoeame solutmn was the most satasfaetory and that 20 e e would be adequate for an adult The majority of the patmnts were 20 to 60 years of age and reqmred this chosen hgnoeame dosage of 20(}1 mg Children up to 15 years of age and patmnts over (}0)rears were gwen smaller doses as determined by each mvestagatm for the mdwadual patmntThe surgmal procedure was begun two to five minutes after the mjeetmn of the hgnoeame, and was completed usually m less than five minutes, so that the