IgG anti‐Jk^a/Jk^b antibodies are unlikely to fix complement

Abstract

Antibodies in the Kidd blood group system show a great deal of serological variability, are notoriously elusive and hence evoke difficulties in detection. However, they have been regularly reported as causing severe immediate or delayed haemolytic transfusion reactions and this clinical potential has been largely attributed to their complement binding ability. In initial investigations on 43 anti-Jka/Jkb sera with a range of titres of IgG antibody only a few seemed to fix complement, though following repeated tests on 20 of these sera a further five were shown to bind complement, making a total of 12 (27.9%) showing evidence of complement binding. Twenty-three sera were unavailable for re-testing. Subsequent tests revealed that only those sera which showed direct agglutination or were positive with an anti-IgM reagent in an indirect antiglobulin test (IAT) fixed complement. Evaluations on the IgG fractions of six selected potent anti-Jka sera failed to reveal any complement-fixing ability although all the original sera bound complement avidly and contained variable amounts of IgM antibody, some at very low subagglutinating levels. These findings challenge past perceptions and give cause for reflection on the changing methodologies and strategies which could unduly compromise the detection of these potentially clinically damaging antibodies.

Plasma cell‐rich acute cellular rejection of a transplanted kidney associated with antibody to the red cell Kidd antigen

“…The absence of C4d deposition suggests that if antibodies are indeed involved in the rejection, it is not a complement‐dependent process. Interestingly, a previously published study found that the IgG class of antibodies to Kidd antigens Jk‐a and Jk‐b do not fix complement (15). On the other hand, a possible mechanism of action for the Jk‐b antibody is by bringing about apoptosis of endothelial cells that express the Jk‐b antigen, similar to what occurs with antibodies to non‐HLA antigens on endothelial cells (16, 17).…”

Kidd Blood Group System

“…A Filipino woman of Chinese and Spanish ancestry, with two children, became Kidd antibodies are usually IgG or a mixture of IgG and IgM; they are rarely pure IgM [38,39] . Around 40 -50% of sera containing Kidd antibodies bind complement; some Kidd antibodies can only be detected in the antiglobulin test when polyspecifi c antiglobulin or anti -complement is used [41,42] . IgG2 may also be present.…”

“…IgG2 may also be present. Only those Kidd sera with an IgM component are capable of complement -binding as IgG Kidd antibodies are unable to fi x complement [42] . Around 40 -50% of sera containing Kidd antibodies bind complement; some Kidd antibodies can only be detected in the antiglobulin test when polyspecifi c antiglobulin or anti -complement is used [41,42] .…”

Rh, Kell, Duffy, and Kidd Antigens and Antibodies

“…Once a Kidd antibody is identified, compatible blood is not difficult to find, because 25% of donors are negative for each antigen. 162 Kidd antibodies only rarely cause HDN; if they do, it is typically not severe. In addition, the antibodies are known to cause delayed hemolytic transfusion reactions and are responsible for at least one third of all cases of delayed hemolytic transfusion reactions.…”