Rhesus antigen

Antibodies can be targeted more or less specifically, either against a single or a variety of antigens. An example of a broad-spectrum antibody therapy is anti-Rhesus antigen antibody (WinRho) which has been used postpartum for many years to prevent rhesus immunization of an Rh— mother by an Rh+ neonate. There are at least 60 known epitopes of the rhesus D antigen. The product is made from pooled plasma of Rh— male volunteers who have been deliberately challenged with small... 

Human IgG antibodies to red cell D antigen (rhesus antigen)... 

At physiological pH, 7.2, 99% of anunonia is in the ionic form. The lui-ionized form diffuses across cell membranes. It was previously thought to simply pass via the phospholipid bilayer but it is now known to use specific transporters in human erythrocytes it is one of the rhesus-antigen proteins (rhesus associated glycoprotein) that mediates the exchange. The NH4+ ion is transported much more slowly via another carrier-mediated process. 

Karl Landstiener was the first to demonstrate the existence of different blood group antigens in 1900. We now recognize 29 different blood group systems comprising over 250 antigens, but the most well known are the ABO (also known as ABH) and rhesus (Rh) systems. 

In the Rh system (not shown), proteins on the surface of the erythrocytes act as antigens. These are known as rhesus factors, as the system was first discovered in rhesus monkeys. 

The rhesus D antigen occurs in 84% of all white individuals, who are therefore Rh-pos-itive. If an Rh-positive child is born to an Rh-negative mother, fetal erythrocytes can enter the mother s circulation during birth and lead to the formation of antibodies (IgG) against the D antigen. This initially has no acute effects on the mother or child. Complications only arise when there is a second pregnancy with an Rh-positive child, as maternal anti-D antibodies cross the placenta to the fetus even before birth and can trigger destruction of the child s Rh-positive erythrocytes [fetal erythroblastosis). 

Anti-D immunoglobulin Human Specificity against rhesus D antigen... 

Gauthier ER, Chapdelaine P, Tremblay RR, Dube JY. Characterization of rhesus monkey prostate specific antigen cDNA. Biochim Biophys Acta 1993 1174 207-210. 

There are several relatively new therapeutic modalities for the treatment of SLE. Trying to eliminate pathogenic anti-dsDNAs, Ferguson etal. developed an antigen-based heteropolymer (AHP) (F3). AHP is a bispecific dsDNA x monoclonal antibody (mAb) complex (dsDNA x anti-CRl mAb) that enables the use of the unique immune complex-binding and clearing capacity of the complement receptor (CR1) on primate erythrocytes. In vitro studies of AHP show a substantial reduction (>90%) of anti-dsDNA titer (F20). In vivo studies in two rhesus monkeys indicate that the erythrocyte-bound antibodies are rapidly cleared from the circulation (F3). 

Other antigenicity study in rhesus monkeys Single dose mice, rats, dogs Repeat dose rats, dogs... 

Steger, K. K., Valentine, P. J., Heffron, F., So, M., and Pauza, C. D. (1999), Recombinant, attenuated Salmonella typhimurium stimulate lymphoproliferative responses to SIV capsid antigen in rhesus macaques, Vaccine, 17, 923-932. 

Earlier, electron microscopic studies showed that when P. knozvlesi merozoites were treated with cytochalasin B (which blocks polymerization of actin) there is an arrest of invasion at the step of junction formation (Miller et al., 1979). When cytochalasin B treatment was carried out with merozoites from the PkDBPa knockouts, no junction was visible with Duffy-positive human red cells (but a junction is formed with rhesus red cells) suggesting that the interaction of PkDBP with the human Duffy antigen is necessary for junction formation and when this critical step is blocked invasion does not occur (Singh et ah, 2005). 

Barnwell, J. W., Howard, R. J., and Miller, L. H. (1982). Altered expression of Plasmodium knowlesi variant antigen on the erythrocyte membrane in splenectomized rhesus monkeys.. Immunol. 128, 224-226. 

Schmidt-Ullrich, R., and Wallach, D. F. (1978). Plasmodium knowlesi-induced antigens in membranes of parasitized rhesus monkey erythrocytes. Proc. Natl. Acad. Sci. USA 75, 4949-4953. 

Schmidt-Ullrich, R., Lightholder, J., and Monroe, M. T. (1983). Protective Plasmodium knowlesi Mr 74,000 antigen in membranes of schizont-infected rhesus erythrocytes. ]. Exp. Med. 158,146-158. 

Hardy L, Rogers B, Thomas D, Ryan A, Peterson M, Koren E, Rowell T, Fuller B, Hobson W. Thrombocytopenia and antigenicity assessment of thrombopoietin treated chimpanzees and rhesus monkeys. The Toxicologist 1997 36 277. 

Bilirubin is measured in amniotic fluid to aid in the assessment of fetal risk in rhesus incompatibility. Incompatible red cell antigens can enter the maternal circulation cither from the fetus at the time of delivery or. rarely, because of incompatible blood transfusion specific red cell antibodies are stimulated in the mother. If. as in rhesus disease, the antibodies arc IgG, they cross the placenta and react with specific antigens on the fetal red cell membrane causing haemolysis (Fig.. 3). This is unusual in a first... 

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