| Description |
1. The incidence of detectable Rh intermediate types, collectively classified as Dµ, is estimated to be between 1.5% and 2 % for a Caucasian population. This in agreement with the only other reported large-scale investigation. 2. Absorption of an anti-d serum with Dµ erythrocytes usually results in lower titers for both the D and Dµ cells, indicating a degree of serological relationship between these agglutinogens. Many Dµ cells can remove all anti-D -/ Dµ antibody; others leave behind a residual antibody or antibodies specific for D. and often for other Dµ cells as well. 3. Evidence from absorption, elution and titration studies support the hypothesis that most Dµ cells differ qualitatively from each other and are also qualitatively different D erythrocytes. Quantitative variations are also observed. In most cases the qualitative aspects are the most prominent. 4. When Dµ erythrocytes are used as absorbing regents, failure of the absorbed serum to react with the absorbing cells is a poor criterion that removal of antibody is a complete as possible with the particular cells. These cells are usually capable to yielding eluates containing anti-D antibody long after the serum gives on visible agglutination with the absorbing cells. 5. Suggestions are made for the detection of Dµ specimens in practical work. The data furnish a reasonable basis for predicting how many Dµ samples will be overlooked if anti-d blocking serums are used with various techniques. 6. The classification of Dµ specimens into grades based on the least sensitive method required to detect them is made. Probably due to serological limitations, the method has an error of approximately 12%. This is too large to be practical. It is suggested that in the absence of a reliable procedure for classification, unusual cases involving Dµ antigens should include a detailed description of the serological activity of the Dµ subtype. 7. When serums absorbed with Dµ erythrocytes are tested against other Dµ cells, a general pattern may be observed. The serologically less reactive samples usually remove increments of antibody than do the more reactive ones, and serums absorbed by them tend to cross-react with larger numbers of Dµ specimens. Conversely, cells of greater serological activity are agglutinated more frequently be serums absorbed with lower grade cells; serums absorbed with cells of higher activity show decreased tendency to agglutinage cells of lower order. Erythrocytes containing ordinary D agglutinogen appear to be capable of removing all antibody from anti-D serums. 8. It is suggest that the genetical activity at the Rh loci may be more complex than indicated by the multiple allele or linked gene theories. Interaction of genes (quantitative inheritance) or the influence of modify genes may be more plausible for explaining many of the serological data. If multiple allelism exists al all, it is probably concerned with subgroups at a particular locus. |
