Two distinct categories of warm autoantibody reactivity with age- fractionated red cells

Abstract

Using age-fractionated erythrocytes, warm autoantibodies can be classified into two distinct categories, depending on their reactivity with reticulocyte-enriched (younger) or reticulocyte-poor (older) red cell fractions. The strength of the direct antiglobulin test (DAT) on the age-fractionated red cells of 24 patients indicated that 19 (79%) had an IgG warm autoantibody that reacted preferentially with older red blood cells. In 7 of these 19 patients (37%), the DAT was negative using reticulocyte-enriched red cell fractions. We have termed this preferential reactivity of warm autoantibodies with older red cells as type I. Five of the 24 patients studied (21%) had an IgG warm autoantibody that demonstrated no preference for young or older red cells. We have termed this pattern of warm autoantibody reactivity as type II. All 5 patients having type II warm autoantibodies had severe anemia. In contrast, 6 of 19 patients having type I warm autoantibody did not have clinical evidence of anemia when tested, and 11 of the 19 had only slight to moderate anemia. Additionally, our results using type I warm autoantibody raise questions regarding the blood group specificity of warm autoantibodies. The antigen recognized by type I warm autoantibody may be a cryptantigen. Rh specificity or relative Rh specificity, often associated with warm autoantibodies, may simply be a coincidental finding.

A major target for warm immunoglobulin G autoantibodies: the third external loop of Band 3

“…On the other hand, according to the Low model, self-tolerance against Band 3 would be a relative phenomenon and high occurrence of autoantibodies to Band 3 may suggest that in various pathologic conditions, activation of a physiologic pathway of RBC elimination leads to hemolytic anemia. 37 Origin 97 68 46 31 20…”

Erythrocyte autoantibodies, the monocyte monolayer assay and in vivo haemolysis

“…MMAs were more strongly positive in patients with both IgG and C3 coating the RBCs than in those with only IgG, although the differences were not statistically significant (Kay & Douglas, 1977). Similarly, IgG alloantibodies which bound complement induced greater interaction with monocytes than those which did not (Branch et al, 1984;Nance et a], 1988).…”

Immunochemical specificity of autoanti‐Gerbich from two patients with autoimmune haemolytic anaemia and concomitant alteration in the red cell membrane sialoglycoprotein β

“…When the haemolytic episode is over, the antigen is again expressed fully so that these red cells are agglutinated by the patient's serum stored at the time of the haemolytic crisis. The cause of this transient weakened expression of blood group antigens is not known, although several theories have been proposed (Conley et al, 1982: Garratty et al, 1983: Branch et al, 1984: Vengelen-Tyler et al, 1987. Of cases of AIHA involving autoanti-a SGP, only one has been reported to be associated with depressed target antigen (EnaTS) (Garratty et al, 1983: Dahr et al, 1986).…”