Blood Group Chimeras

Abstract

More than 70 spontaneous chimeric propositi in man are known. This review attempts to summarize the information given by 32 twin chimeras, 32 dispermie chimeras and 11 chimeras of unestablished type.

Placental chimerism in early human pregnancy

“…[5] Chimerism in human considered as rare phenomenon. [6] However, some investigators observed this more frequently than previously recognized. [7][8][9] In recent years, due to interference through assisted reproductive techniques, chimerism either confined to placenta or blood or true is seen more frequently in human.…”

DNA typing in cases of blood chimerism

“…A spontaneous chimerism is due to blood vessel anastomoses between dissimilar twins in uterine life and a subsequent transfusion of red blood stem cells and lymphoid stem cells passing through foetal anastomoses. Some of the invading cells become established in the marrow of the host who throughout life continues to make cells with both genetic patterns (Tippett 1983). During this foetal stage a natural suppression of the immune response occurs and enables the organism to recognise cells as self which might otherwise be antigenic.…”

“…During this foetal stage a natural suppression of the immune response occurs and enables the organism to recognise cells as self which might otherwise be antigenic. Thus the genetically foreign cells are prevented from a immune response by the individuals own potential antigens (Tippett 1983). In humans this is the most common type of blood chimerism and is permanently established in an individual in contrast to the artificial chimerism.…”

“…Thus different intensities and a higher number of signals can be obtained. Tippett (1983) pointed out that in some cases the proportion of foreign cell populations even exceeds the original genotype. According to Hosoi et al (1977) the proportion of foreign cells depends on the period of the anastomoses.…”

Editorial. The long term effects of breast feeding: a role for the cells in breast milk?

“…Some non-identical twins have been found to express two blood group antigens of their siblings for many years, suggesting a stable tolerance of a foreign lymphoid cell graft. 15 In older individuals following transplantation of solid organs, microchimaerism is present, but is usually dependent on immunosuppression. Early activation of the immune system in the neonate by infectious agents may protect against the development of allergic diseases.…”