Anti‐N in the Serum of a Healthy Blood Donor of Group MN

Abstract

Summary A most unusual combination of serological findings in a healthy blood donor is described. His blood group is A1, and his red cells are weakly H positive; they are type MN, both the M and N antigens being of normal strength. His saliva contains A and H substances. His serum shows weak anti‐H and anti‐N activity which is best demonstrated at 12° to 16°, but is hardly detectable at 37°. This dual specificity, according to the results of agglutination tests and absorption experiments, appears to be due to two distinct antibodies, both of natural origin. The anti‐H is neutralized by the donor's own saliva. The donor presents no clinical or serological signs of auto‐immunization. Résumé Les auteurs décrivent une combinaison absolument inhabituelle des résultats sérologiques obtenus avec le sang d'un donneur de sang en bonne santé. Le groupe sanguin de ce donneur est A1, ses érythrocytes sont faiblement H positif; ils sont du type MN, les deux antigènes M et N étant de force normale. La salive de ce donneur contient des substances A et H. Son sérum présente une faible activité anti‐H et anti‐N, dont l'optimum thermique de réaction se situe de 12 à 16° C, mais qui est difficilement décelable à 37° C. Cette double spécificité, mise en évidence par les tests d'agglutination et confirmée par les épreuves d'absorption semble être due à deux anticorps distincts, tous deux d'origine naturelle. L'anti‐H est inhibé par la salive du donneur lui‐même. Ce donneur ne présente aucun des signes cliniques ou sérologiques d'un processus d'auto‐immunisation. Zusammenfassung Eine äußerst ungewöhnliche Kombination von serologischen Befunden bei einem gesunden Blutspender wird beschrieben. Seine Blutgruppe ist A,; seine Erythrozyten sind schwach H‐positiv. Er zeigt die Faktorenkombination MN; die Antigene M und N sind normal ausgeprägt. Sein Speichel enthält A‐ und H‐Substanz. Sein Serum zeigt eine schwache Anti‐H‐ und Anti‐N‐Aktivität, welche am besten bei Temperaturen von 12–16°C zur Darstellung gelangt. Bei 37°C ist sie kaum nachzuweisen. Auf Grund der Agglutinations‐ und Absorptionsversuche erscheint die Annahme am naheliegendsten, daß diese Doppelspezifität auf zwei verschiedene natürliche Antikörper zurückzuführen ist. Der Anti‐H‐Antikörper wird durch den Speichel des Spenders inaktiviert. Der Spender zeigte weder klinische noch serologische Zeichen einer Autoimmunisierung.

Anti-N-Like Antibodies in the Sera of Patients Undergoing Chronic Hemodialysis

“…Cases of anti-N in N-positive individuals have been rare enough to warrant separate case reports [2,5,6]. In contrast to these observations, 12 cases of antibody with apparent N specificity have been detected within a period of two years.…”

“…Second, the antibody developed in N-positive patients in eight of the 12 cases, whereas only three previous examples of auto-anti-N have been reported [2,5,6]. Finally, the red cell antigenic determinants with which these antibodies reacted appeared somewhat more resistant to treatment with proteolytic enzymes than the determinants with which other examples of human anti-N have reacted [9].…”

Automated Red Cell Antibody Analysis. A Parallel Study

“…Here again the findings are questionable, but can be compared to previously reported cases [7,18,21,26] of anti-M and anti-N detected in individuals positive for the M and N antigens respectively, were the antibody was detectable by manual methods.…”

The First Example of Auto-Anti-M and its Consequences in Pregnancy

“…Within the MN system at least two examples of anti-N in MN individuals reactive with the patient's cells have been described [2,4]. To the best of our knowledge this is the first example of a human autohemagglutinin with anti-M specificity.…”