Characterization of the D, c, E and G antigens of the Rh blood group system with human monoclonal antibodies

The human MAbs, anti-D, -c, -E and -G of the Rh blood group system, produced by Epstein-Barr virus transformed B-cell lines, were purified by protein A-Sepharose chromatography and used to characterize the Rh antigens of human red cells. Scatchard plot analyses performed with the radiolabelled MABs indicated that each R2R2 red cell carries 0.43, 0.32 and 0.38 x 10(5) D, c and E binding sites, respectively. About half this number of antigen sites are present on erythrocytes from heterozygote individuals using the appropriate antibody. We found, however, that only 0.18 x 10(5)G antigenic sites were present on each R1R1 red cell. The affinity constants of the anti-D, -E and -G were similar varying from 0.6 to 1.5 x 10(8) M-1 whereas that of the anti-c was much lower (0.035 x 10(8) M-1). The blood group specificity and binding properties indicate that the MAbs behave like the polyclonal anti-Rh reagents. Immunoprecipitation experiments carried out with membranes from R2R2 red cells show that a 30-32 kDa component can be identified whatever the antibody used. The immune complexes involving anti-c, -E or -G antibodies could be formed with the detergent lysates from red cell membranes. In contrast, membrane integrity was a prerequisite for the binding of the anti-D antibodies. Finally, from extraction studies of immunocomplexes with non-ionic detergents it was concluded that all the Rh-active components are bound to the membrane skeleton, suggesting that these molecules may have important function for maintaining red cell shape and viability.

Determination of the N-terminal sequence of human red cell Rh(D) polypeptide and demonstration that the Rh(D), (c), and (E) antigens are carried by distinct polypeptide chains

Human monoclonal antibodies (MoAbs) directed against the blood group Rh(D), (c), and (E) antigens produced by Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines have been used to characterize the Rh components of human red cell membranes and to determine whether the Rh(D), (c), and (E) epitopes are carried by distinct polypeptides. After immunoprecipitation with the anti-Rh(D) antibody and preparative gel electrophoresis, a homogenous preparation of the Rh(D) protein was obtained from two different erythrocyte samples (Blo and D--/D--), which have an increased density of Rh(D) antigen. Both preparations exhibited the same N-terminal sequence (S)-(S)-K-Y-P-R-S-V-R-R-(L)-L-P-L-X-A, indicating that different Rh(D)-positive red cells are carrying a similar Rh(D) protein. Comparative immunoprecipitation studies with the human monoclonal anti-Rh(D), (c), and (E) antibodies have also shown that Rh components from intact and papain-treated erythrocytes have similar apparent mol wt of 30 to 32 Kd and are buried in the lipid bilayer and are not readily available to the proteolytic enzyme. Further investigations by indirect affinity chromatography and one-dimensional peptide mapping of the Rh(D), (c), and (E) molecules immunopurified from a single red cell sample demonstrate that a common Rh haplotype encodes three distinct polypeptide chains carrying the Rh(D), (c), and (E) epitopes, respectively.

Blood groups in Papua New Guinea Eastern Highlands

Blood group polymorphisms were analysed in inhabitants of Papua New Guinea Eastern Highlands. The aim of the study was to assess the situation of the Baruya tribe among other Anga peoples: Youwarounatche, Andje, Usarumpia, Langimar. A non-Anga tribe, the Aziana, was also sampled. ABO, RH, MNS, P, KEL, FY and JK systems were tested in each group. ABO*O gene was predominant, ABO*Aint was relatively high, ABO*B was rare in all tribes and absent in the Usarumpia tested. The Ns haplotype was the most frequent in MNS system. All tested subjects were RH*D, KEL (-) and FY (a+b-), with very few exceptions. The presence of one CcdEe and 5 FY (a+b+) subjects may be due to foreign admixture. A noteworthy genetic microdifferentiation was observed between tribes. Geographical isolation and genetic drift has played an important role in the differentiation of the various groups.

Cellular localization of blood group antigens (including HLA markers) in human bladder urothelium

Expression of A, B, H, Lewis, I, i, HLA class I and class II antigens was studied on 81 urinary bladder samples. Striking variation in the expression of HLA class II and to a lesser extent of HLA class I determinants was observed. Expression of at least five distinct A (or B) determinants, the synthesis of which is controlled by H, A, B, secretor and Lewis genes, was demonstrated by using a panel of reagents directed against different A, B and H epitopes. These results suggest that evaluation of blood group changes during tumoral processes requires the precise determination of the specificity of reagents used and the knowledge of ABO, Lewis and secretor phenotypes for each patient. ABH and related antigens should now be regarded as tissue antigens with a complex genetic regulation and expression.

Management of alloimmune thrombocytopenia: antenatal diagnosis and in utero transfusion of maternal platelets

Neonatal alloimmune thrombocytopenia (NAIT) can cause severe bleeding in the central nervous system (CNS) and death or severe neurologic sequelae. The expression of the PLA1 antigen is detectable as early as 19 weeks of gestation. Alloimmunization can therefore lead to fetal thrombocytopenia very early in pregnancy. Until recently, we have had no means of detecting and assessing the severity of fetal thrombocytopenia during pregnancy. The level of the maternal antibody is not of a predictable value since 20% of the mothers had no circulating antibodies in our series. An alternative approach is to carry out investigations on fetal blood samplings. This management leads to an exact knowledge of the fetal status and antenatal diagnosis is feasible as early as the 21st week of gestation. Early diagnosis facilitates appropriate management and makes possible such therapeutic options as in utero maternal platelet transfusions. We report our experience in the antenatal diagnosis and management of nine cases with in utero transfusion in the six cases with severe thrombocytopenia. All neonates did well, with no signs of bleeding at birth. No side effects of therapy were noted after a period ranging from 6 months to 3 years.

Biochemical identification and characterization of the G antigen in the human blood group Rh

The human blood group Rh comprises erythrocyte membrane antigens which include the G antigen. In order to carry out this study, the G antigen was specifically immunofixed with a human monoclonal anti-Rh(G) antibody. After extraction and purification of the antigenic complex, a migration in SDS-PAGE showed the G antigen to be associated with a polypeptide of 28,000 MW.

Disappearance of CD4-lymphocyte circadian cycles in HIV-infected patients: early event during asymptomatic infection

Circadian variations have been observed in peripheral blood lymphocyte counts in normal subjects; they usually reflect variations in absolute CD4-cell count. For this population, nadir occurs around 0800 h (basal value) and the peak value occurs at midnight (1.6 times the 0800-h value). This cycle is thought to be of major importance in the efficacy of the immune response because it expresses the migration of lymphocytes into lymphoid organs.

Frequency of red cell adenosine deaminase phenotypes in a unique Breton community, the Bigoudens

The adenosine deaminase gene frequencies were calculated in 405 subjects randomly chosen from the Bigouden district. A rather high frequency (0.0765 +/- 0.0093) was found for the ADA2 gene. The possible effect of Celtic influences is considered.