Antigenic Stimuli Rh antibodies are usually immune, i.e., red cell stimulated as a result of pregnancy or transfusion. Rarely, some Rh antibodies (such as anti-E) may be non-red cell stimulated, i.e., naturally occurring.

Immunoglobulin Classes Most Rh antibodies are IgG, although some can be IgM or a combination of both IgG and IgM. Anti-E is more likely to be IgM than other Rh antibodies. Anti-D is often seen as a mainly IgM antibody in a 1° immune response. Rarely, some Rh antibodies such as anti-e may occur as IgA antibodies.

Clinical Significance Rh antibodies are clinically significant antibodies that can react at 37°C and cause in vivo red cell destruction via EVH, mainly in the spleen. They are common causes of delayed hemolytic transfusion reactions and of HDN.

Phases of Reactivity Rh antibodies react best of all in enzyme phases and also react well in the antiglobulin phase. They also react in albumin phases and, if IgM, can react in saline phases also.

Complement Binding Rh alloantibodies do not usually bind complement.

Dosage Effect

Enrichment Activity 2

Historically, Rh antibodies have been the major cause of severe hemolytic disease of the newborn (HDN). Read Rh antibodies as a cause of HDN, a Medline abstract of a Swedish study. list.

  1. Post a comment or question about this study. For example, comment on the blood group systems that are mentioned as requiring treatment such as phototherapy or exchange transfusion. Or speculate as to why Rh antibodies tend to cause the most severe HDN.

  2. Post a comment or reply in response to a comment or question made by another participant about the Swedish study.

  3. Many laboratories have different policies related to weak D (Du) testing. Outline the protocols used in your laboratory (or geographical area) for weak D typing of the following:

    (a) transfusion recipients

    (b) pregnant females

    (c) newborns of Rh negative mothers

  4. Briefly discuss under which circumstances in your laboratory (or geographical area) that Rh negative patients may receive Rh positive red cells.