Collaborative study of irregular erythrocyte antibodies in Japan: Results from the Japanese study group of allo-immunity and antigen diversity in Asian populations

A single-center, retrospective analysis of 17 cases of hemolytic disease of the fetus and newborn caused by anti-M antibodies

OBJECTIVE

We aimed to summarize the laboratory findings and clinical features of hemolytic disease of the fetus and newborn (HDFN).

METHODS

We retrospectively analyzed the data for 17 infants with anti-M-induced HDFN (anti-M-HDFN) diagnosed between June 2013 and May 2019. Their maternal history, neonatal diagnosis on admission, and laboratory test results were compared with those of 15 infants with HDFN involving the ABO blood group system, 15 infants with HDFN involving the Rh system, and 15 premature infants.

RESULTS

In the anti-M-HDFN group, 94.12% (16/17), 35.29% (6/17), and 17.65% (3/17) had free antibodies in plasma, a positive direct antiglobulin test, and a positive elution test, respectively. In 12 infants, free antibody reactions were stronger at 4°C than at 37°C, and the antibody titer at 4°C ranged from 1 to 512. All 17 infants with anti-M-HDFN developed anemia: 14 were treated with blood transfusion and 1 with neonatal exchange transfusion. Sixteen infants improved, and one died. Anti-M-HDFN had a higher rate of maternal stillbirth, lower gestational age, lower birthweight, and higher incidence of respiratory distress than other HDFN types.

CONCLUSION

Anti-M may cause HDFN. It may present with varying degrees of anemia, low regenerative anemia, and low bilirubin levels. In addition, infants with anti-M-HDFN may have a negative elution test and direct antiglobulin test. These tests are helpful in examining antibody responses at a low temperature of 4°C.

Potential applications of ficin in the production of traditional cheeses and protein hydrolysates

Using proteolytic enzymes extracted from plant materials is a promising way to ensure the sustainability of the food industry. This is particularly true for the dairy industry, especially in cheesemaking and the production of different milk protein hydrolysates for special food applications, particularly nutrition for infants, older adults, and people with food allergies. Ficin, a cysteyl protease isolated from the latex of the fig tree (Ficus carica), is characterized by strong enzymatic activity and can be used for milk clotting and protein hydrolysis for application in different foods. In particular, it can be used for milk protein hydrolysis to produce ingredients with reduced or eliminated allergenicity and improved bioavailability. Ficin can also be used as an active and effective replacement for calf rennet in cheesemaking, such as in traditional Cacioricotta and Teleme cheeses. It can also be used to produce protein hydrolysates with low or no allergenicity for application in infant formula and geriatric nutrition. This work provides an overview of ficin, a plant-derived protease, with an emphasis on its potential application in the production of some traditional cheeses and milk protein hydrolysates for special food applications.

Erythrocyte Alloimmunity and Genetic Variance: Results from the Collaborative Study of Alloimmunity to Antigen Diversity in Asian Populations (All ADP)

As an East-Asian international study, we evaluated erythrocyte alloimmunity by gender and history of transfusion or pregnancy. In total, data from more than 1,826,000 patients were analyzed, from whom 26,170 irregular erythrocyte antibodies were detected in 22,653 cases. Antibody frequencies in these cases were as follows: anti-E, 26.8%; anti-Le^a, 20.0%; anti-P1, 7.1%; anti-M, 6.4%; anti-Mi^a, 5.6%; anti-c + E, 5.6%; anti-Le^b, 4.6%; anti-D, 2.8%; anti-Fy^b, 2.6%; anti-Le^a+Le^b, 2.5%; anti-Di^a, 2.0%; and others. For pregnant patients, anti-D (12.7%) was statistically more frequent. For transfused patients, anti-E (37.3%), anti-c + E (9.5%), anti-C + e (3.3%) and anti-Jk^a (3.1%) were significantly more frequent.

Three non-classical mechanisms for anemic disease of the fetus and newborn, based on maternal anti-Kell, anti-Ge3, anti-M, and anti-Jra cases

Maternal alloantibody-mediated hemolytic disease of the fetus and newborn (HDFN) ranges from no or mild symptoms to severe hydrops and intrauterine fetal demise. Hemolytic anti-D-mediated HDFN proceeds via a long-known mechanism, to which three other pathways to fetal/neonatal anemia may be added: (0) Fetal erythrocyte destruction can proceed by extravascular phagocytosis. (1) An apoptotic pathway has been described for anti-Kell, and anti-Ge3. (2) Erythropoietic suppression may arise from altered or deformed erythroblast architecture in anti-M-mediated disease. (3) Clonal escape from erythropoietic suppression is hypothesized to arise from maternal anti-Jr^a immune pressure, albeit this requires further elucidation. Alloantibody-mediated anemic disease of the fetus and newborn (ADFN) is a designation we favor for cases when hemolysis or hyperbilirubinemia are not the dominant features, such as those provoked by anti-Kell, anti-Ge3, anti-M, and anti-Jr^a.

Transfusion-Related Alloimmunization to Red Blood Cell Antigens in Japanese Pediatric Recipients

Red blood cell (RBC) transfusion to neonates is thought to rarely provoke an immune response. Neonatal testing guidelines suggest that antibody screening is not necessary when the mother has no antibodies. Alternatively, maternal blood samples can be used for antibody screening and cross-matching. However, the guidelines are based on small-scale studies of white-dominant populations. Furthermore, transfusion-related alloimmunization is less well established among children and adolescents as a whole among Japanese and East Asians. To elucidate the incidence of transfusion-related alloimmunization among neonates, children, and adolescents, and whether current guidelines are applicable to Japanese populations, a nationwide retrospective multicenter cohort survey was conducted in 50 tertiary-care hospitals in Japan. Between 2001 and 2015 inclusive, recipients of at least 1 allogeneic RBC transfusion were categorized into groups A-F according to their age at the time of transfusion: (A) neonates <1 month; (B) infants 1 to <12 months; (C) children 1 to <5 years; (D) prepubescents 5 to <10 years; (E) young pubescents 10 to <15 years; and (F) adolescents/young adults 15 to <20 years. Excluding maternally derived antibodies and naturally occurring, cold-reactive, and/or nonspecific antibodies, 69 (0.61%) of 11350 RBC recipients <20 years old formed at least 1 clinically significant alloantibody. The alloimmunization rate differed significantly (P < .0001) by age: none (0%) of 3407 in group A; 11 (0.46%) of 2410 in group B; 18 (0.76%) of 2361 in group C; 9 (0.80%) of 1119 in group D; 12 (1.15%) of 1043 in group E; and 19 (1.88%) of 1010 in group F. Clearly different incidences of alloimmunization emerged in group A compared to B, C, D, E, or F, as confirmed by logistic regression analysis adjusted by numbers of donor exposure. Alloimmunization did not occur from RBC transfusions within the first month of life and rarely occurred (0.46%-0.80%) after transfusion within the first decade of life. Alloimmunization occurred in 1.15%-1.88% of young pubescents and adolescents/young adults. These findings support the use of guidelines developed in Europe and the United States for East Asian pediatric recipients.

Anemic Disease of the Newborn With Little Increase in Hemolysis and Erythropoiesis Due to Maternal Anti-Jra: A Case Study and Review of the Literature

The severity of the hemolytic disease of the fetus and newborn (HDFN) due to Jr^a mismatch ranges from no symptoms to severe anemia that requires intrauterine and exchange transfusions. We encountered a newborn, born to a healthy mother having anti-Jr^a at 38 weeks of pregnancy, who had moderate anemia, a positive direct antiglobulin test (DAT) result, no increased erythropoiesis, and no jaundice at birth. Flow cytometry revealed that the Jr^a antigen of red cells in the infant was nearly negative at birth, biphasic at 5 weeks, and lowly expressed at 7 months of life. We searched online for previous case reports on HDFN due to Jr^a incompatibility. Among 63 reported cases, excluding 25 cases, 38 were included with the present case for analysis. Of 39 newborns, 10 developed clear anemia (hemoglobin <10.0 g/dL), and 1 died, 5 developed hydrops fetalis, 4 needed intrauterine transfusion and/or exchange transfusion, and 3 received red cell transfusion after birth; overlaps were included. Among 29 neonates with no anemia, 8 needed interventions including phototherapy and γ-globulin infusion, and the remaining 21 received conservative supports only. The maternal anti-Jr^a titer, ranging between 4 and 2048, did not correlate with the severity of anemia, levels of bilirubin, or any interventions required. The DAT of red cells was positive in 29 of 36 fetuses/newborns tested, whereas it was often negative among anemic neonates (4 of 9) (P < .05). Hematopoiesis did not increase effectively, as indicated by reticulocyte ratios between 1.7% and 22.3%, even with the increase in reticulocytes in anemic neonates compared with nonanemic neonates (P < .05). Total bilirubin levels ranged broadly between 0.2 and 14.3 mg/dL but were generally low. The maternal anti-Jr^a titer and IgG3 subclass did not correlate with the morbidity of the newborns. Being identical/compatible between mothers and their infants may possibly enhance infants' morbidity, as a weak tendency was observed (P = .053). Maternal anti-Jr^a may suppress erythropoiesis in fetuses via a mechanism different from the established HDFN, such as anti-D, as evidenced by the lower reticulocyte count and small increase in bilirubin in neonates. As the anti-Jr^a titer, IgG subclass, and DAT were not correlated with the severity, the mechanism of anti-Jr^a-induced HDFN remains to be elucidated.

Hemolytic disease of the fetus and newborn with late-onset anemia due to anti-M: a case report and review of the Japanese literature

Hemolytic disease of the fetus and newborn (HDFN) attributed to M/N-incompatibility varies from asymptomatic to lethally hydropic. Case reports are rare, and the clinical significance of anti-M is not completely understood. A challenging case of HDFN due to anti-M prompted an investigation of the Japanese literature, in order to characterize the clinical spectrum of M/N-incompatibility pregnancies in Japan and report results to English-language readers. Japanese reports of HDFN attributed to M/N incompatibility were compiled. Abstracted data include maternal antibody titers at delivery, fetal direct antiglobulin test, hemoglobin, total bilirubin, reticulocyte count at birth, and therapeutic interventions. We investigated characteristics of HDFN due to M/N-incompatible pregnancies in Japan after encountering a case of severe HDFN along with late-onset anemia in an infant born to a woman carrying IgG anti-M with a titer of 1. In total, thirty-three babies with HDFN due to anti-M and one due to anti-N have been reported in Japan since 1975. The median maternal antibody titer was 64 at delivery and was 16 or less in 10 of 34 women (29%). Five of 34 babies (15%) were stillborn or died as neonates. Twenty-one of 29 survivors (72%) had severe hemolytic anemia and/or hydrops fetalis. The reticulocyte count of neonates with anemia stayed below the reference interval. Sixteen (55%) developed late-onset anemia and 14 (48%) were transfused with M-negative RBCs. Significant positive correlation (P < .05) between the hemoglobin value and the reticulocyte count within 4 days of birth was obtained in 16 babies with anti-M HDFN. In the Japanese population, 21 of 34 cases of M/N-incompatible HDFN (72%) have manifested as severe hemolytic anemia and/or hydrops fetalis. Low reticulocyte count in neonates with late-onset anemia is consistent with suppressed erythropoiesis due to anti-M.

Rh, Kell, Duffy, Kidd and Diego blood group system polymorphism in Brazilian Japanese descendants

Polymorphisms of Rh, Kell, Duffy, Kidd and Diego blood group systems were studied in 209 unrelated Brazilian Japanese descendants from South of Brazil. The methods used were multiplex-PCR, AS-PCR and RFLP-PCR. The differences in frequencies among the populations were evaluated using chi-square test. The frequencies for Rh, Kell, Kidd and Diego system were similar to those of the Japanese. RHCE(*)CC, RHCE(*)EE genotypes and FY(*)01 allele were lower and FY(*)01N.01 was higher than Japanese. These differences in the frequencies between Brazilian Japanese descendants and Japanese could indicate a gene flow in Brazilian population and reinforce the importance of this knowledge to achieve safe red blood cells.