A United States Army Medical Department continuing Education program, the 24 th annual Armed Forces seminar on obstetrics and Gynecology. The Association of anti HL antibody and obstetrical complications with Robert E Harris, Lieutenant Colonel MC US, Air Force, OBGYN Department, Wilford Hall US Air Force Medical Center, Texas. Their constituents of cells are extremely important to us the day I would like to present to you the association that we have found a maternal lymphocytotoxic antibodies with obstetrical complications and fetal sex. Next line, the HL A or the human leucocyte antigen is becoming increasingly more important to the understanding of the immunology of obstetrics and pregnancy. One postulate for the lack of rejection of the normal fetuses has been a masking these paternal antigens on fetal cells thus rendering them more tolerant to the mother. Next line, the HL A antigens are determined by several closely linked genetic low side that are inherited on one pair of chromosomes. Thus, usually there exists an incompatibility between the mother and the paternal h antigens of the fetus. Next line, the hlan engines are present early in ontogeny. They have been demonstrated in spleen lung, liver and kidney and 3 to 5.5 month human fetuses. Next slide please. And 20 to 50% of pregnant women have lymphocytotoxic antibodies against the paternal HL A antigens. This percent is known to increase with parity. Next line in our prospective study, we obtained Sarah from 20 patients at the time of spontaneous abortion and 180 patients at the initial obstetrical clinic visit and 129 patients were followed 6 to 7 months. A form was initiated and then was completed after delivery. Sarah was obtained at 28 and 30 weeks, 36 weeks, chest station and at delivery. Next line s was typed for cytotoxic activity against lymphocytes. And a given serum was considered positive for cytotoxic activity. When it reacted with 10% or more of a panel of 30 lymphocytes from normal population Neel at delivery, the infant's cord blood and the blood from the patient's husband whenever he was available were obtained for L A. Next slide of the there were 23 abortions, 20 that spontaneously aborted that we obtained samples from and three of the 180 patients and none of these abortions. Did we detect any lymphocytotoxic antibody? However, 28 of 129 or 22% of the patients developed lymphocytotoxic antibody during the chest station of those patients that were followed for the 6 to 7 month period. Next slide please. In the results we analyzed this according to two groups, those patients who had cytotoxic antibodies and those who did not have cytotoxic antibodies. As you can see, the age of the patients was pretty much the same with less than 20 years being represented. 66% of those patients who did have antibodies presence and absent. Those patients had 66 62% of those were under 20 years. As would be expected in the multi paris group, 71% of the multi paris patients fell into those patients who did have cytotoxic antibodies. And 52% were among the group that had no antibodies present. The overall complication rate in obstetrics was somewhat surprising to us. And there were 50% of those patients who did have lymphocytotoxic antibodies did have an obstetrical complication during the course of her pregnancy. As compared to 29% of those patients that did not have antibodies. There was really no difference in the median infant weight of the two groups in the median being 3375 g as compared to 3402 g. Next line, the is a little difficult for you to see. But the striking thing we found was that 12% of these patients had preeclampsia as compared to only 5% of those patients who did not have lymphocytotoxic antibodies and fetal stress was present and 16% of those patients as compared to six and fetal stress was manifested by fetal brady cardia and meconium staining. There was one unexplained fetal death among the group with antibodies and in the injury growth retardation, there was one infant for 4% and we had no injury growth retarded infants. Among the other 101 patients who did not have any antibodies. In a previous report. In a retrospective analysis, it had been stated that those mothers who had lymphocytotoxic antibodies had a higher instance of congenitally defective infants. In our prospective analysis, we had no congenitally anomalous infants or fetuses delivered to those mothers who had antibodies. And there were two for 2% in the 101 patients who did not have any antibodies present. Next line, please. HL A typing was done on the cord blood. It has been reported that it is difficult to type these infants cord blood. As far as the HL A in our group, only eight of the 28 infants were typable for these eight. The lymphocytotoxic antibody was specific for the paternal HL A antigen on the fetal cells. For nine of the 13 husbands syrup that were obtained. Maternal antibodies were demonstrated then to be directed against the paternal HL A antigen system. Next line. And one thing that was of interest to us that we did not anticipate was that there has been experimental evidence that maternal fetal disparity for his ability antigens favors a fetal survival particularly for male offspring. And this has been done with mice and rats. And recently just this summer, one of the person from England, his phd thesis came up with the evidence in humans that this was a true also in humans. When we analyzed our data. Next slide, we were struck with the fact of an infant male to female ratio. And those mothers who had maternal lymphocytotoxic antibodies was 4 to 3, the ratio of males to females and those mothers who had absent antibodies was 2 to 5. Next, in conclusion, we cannot say anything about the fetal sex at this point except that it is interesting. We feel that there is more data that is needed in a further prospective study. If this data is confirmed, it may indicate that the HL A system may be a prospective analysis that we can do on obstetrical patients, determine those patients at high risk in certain categories and also to try to prevent some of the problems that we have. Thank you very much. This program was produced through the mobile facilities of the television branch, Health Sciences, media division, Academy of Health Sciences, United States Army, Fort Sam Houston, Texas.