I18 CORRESPONDENCE TRANSFUSION Vol. 21. No. I - 19x7

On the inheritance of the EP red cell antigen To the Editor:

The E P antigen is established and has the number 019 in the 900 series (ISBT numerical designations).’ Individuals with the Er( a-) phenotype have been described in four fa mi lie^,^.^ but no definite conclusions about the mode of inheritance of the Er(a-) phenotype have been possible. Daniels et aL2 made two suggestions: a rare recessive gene at the Er locus or a dominant inhibitor of the Er“ gene. They pointed out that study of more families with an Er(a-) member was likely to resolve this problem. We investigated a large Danish kindred with an Er(a-) prop- osita; in this family a recessive trait seemed most likely.

The proposita was a 71-year-old woman who had been pregnant six times (five normal deliveries and one miscar- riage) and transfused on three occasions in the period 1955 to 1975. One unit of blood (1966) was followed by shiver- ing and fever (39.8OC). On admission an antibody screen- ing test was positive and the patient’s serum reacted with all red cells except her own by indirect antiglobulin and enzyme techniques. Red cells lacking the antigens Buck- alew, Ch, Coa, Cra, Ge, Hy, J M H , Joa, Jra, Kpb, Lan, Lub, Lu8, Lu12, Rg, U, Vel, and Yta were incompatible. The serum from our patient was compatible only with red cells from a propositus who is Er(a-).2 The anti-Era from this propositus did not react with the red cells of our patient. Therefore, we concluded that our patient was Er(a-) and had anti-Era in her serum. Our findings were confirmed by the Quebec City Transfusion Centre, Canada.

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FIG. I . Family pedigree of an Er(a-) proposita favoring a recessive mode of inheritance. 0 -deceased; 0-Er(a-); @ - Er(a+); @-Era typing impossible due to ABO type; 0-not tested (all young children).

There was no consanguinity of the proposita’s parents. Family members were typed for red cell antigens including Era. Some could not be typed for Era because of ABO incompatibility. None of the tested family members was found to be Er(a-) (Fig. I). Seven of eight first-degree rel- atives were typed and shown to be Er(a+). The eighth could not be typed because of ABO incompatibility. Therefore, a dominant inhibitor of the Er gene seems unlikely in this family. Our results favor a recessive mode of inheritance to explain the Er(a-) phenotype.

KIRSTEN LYLLOFF, M D J 0 R G E N GEORGSEN, M D

NlELS GRUNNET, MD, DSC CASPER JERSILD, MD, DSC

Regional Centre for Blood Transfusion and Clinical Immunology

Aalborg Hospital, DK-9100 Aalborg

Denmark

References I . Lewis M, Allen FH Jr , Anstee DJ, et al. ISBT working party

on a terminology for red cell surface antigens: Munich report. Vox Sang 1985;49:171-5.

2. Daniels GL, Judd WJ, Moore BPL, et al. A “new” high fre- quency antigen Era. Transfusion 1982;22: 189-93.

3. Thompson HW, Skradski KJ, Thoreson J R , Polesky HF. Sur- vival of Er(a+) red cells in a patient with allo-anti-Era. Trans- fusion 1985;25:140-1.

HLA antibodies in blood donors with reactive screening tests for antibody to the immunodeficiency virus

To the Editor: HLA DR4 and DQw3 antibodies may cause positive

reactions in the enzyme-linked immunosorbent assay (EIA) used to detect antibodies to human immunodeficiency virus (HIV). Kuhnl et al. reported that 10 of 27 DR4 alloantiserums were reactive, whereas, Hunter and Meni- tove found one of five anti-DR4 and three of four anti- DQw3 serums to be Nine of 20 repeatedly EIA- reactive blood donors showed anti-DR4 and/ or DQw3 reactivity.

Repeatedly reactive blood samples are currently being screened for HLA antibodies at our center. HLA antibody testing has been performed on samples from 211 donors who had repeatedly EIA (Abbott Laboratories, North Chicago, IL)-reactive tests. One hundred nine of the 21 1 donors were female. All 109 female donors and 93 of 102 male donors were EIA-reactive, Western blot-negative (Hoxworth in-house Western blot). Of the 211 donors, samples from nine men were EIA-reactive, Western-blot- positive. Of the 202 donors reactive only with EIA, 27 had anti-HLA in the serum. Twenty-three of those 27 were female donors and all were multiparous. Two of nine Western blot-positive donors had anti-HLA. Both were male donors with multispecific DR antibodies. More detailed results are shown in Table I .

Two of the high-titer antiserums were chosen at random and absorbed with pooled platelets to remove antibodies to antigens controlled from the A and B loci. After absorp- tion, both serums were retested and found to have underly- ing DR antibodies. Both serums were also still EIA- reactive. Two of the donor serums with DR4 antibodies were chosen at random and were absorbed with DR4- positive B-cells. The preabsorption samples were EIA- positive; the postabsorption samples were E l A-negative. This demonstrated the sensitivity of the EIA test system to DR4 antibodies. To show this sensitivity further, eight local HLA reagent antiserums from multiparous women were subjected to the anti-HIV EIA test. The only serum that reacted was the one with DR4 specificity.

These data indicate that reactivity in the anti-HIV EIA assay can be due to HLA antibodies, particularly those

Table 1 . Results of tests for nonspecificity

EIA-reactive

Anti-HIV-reactive Western blot-negative blot-positive

Blood donors n = 202 n = 9 HLA antibodies 5 indeterminate.

El A-Reactive, Western

2 multispecific 10 multispecific DR Abs 9 DR4 1 DR9 1 827 1 88

DR Abs

Very high titer-unable to determine specificity.

TRANSFUSION 1987-Vol. 27. No I

CORRESPONDENCE 119

that define DR4 and DQw3. EIA-positive, Western blot- negative samples with HLA antibodies may be further tested by absorbing the HLA antibodies from serums and retesting for anti-HIV. A negative result for anti-HIV, after absorption, suggests a false-positive result due to HLA antibodies.

Other antigens unrelated to HIV present in the assay system could also account for false-positives. HLA antibod- ies were found in only 14 percent of the EIA-positive, Western blot-negative samples. It is obvious that factors other than HLA antibodies cause false-positive reactions. Verification of all anti-HIV EIA-positive serums by Western blot is essential until a more specific test for HIV antibodies can be developed.

MATTHEW BLANTON, MT(ASCP) KAMALA BALAKRISHNAN, MD UMAKANT DUMASWALA, PHD

TIBOR J. GREENWALT, M D Hoxworth Blood Center University of Cincinnati

Cincinnati, OH 45267

KAY ZELENSKI, PHD

References

1. Kuhnl P, Seidl S, Holzberger G . HLA DR4 antibodies cause positive HTLV-Ill antibody results. Lancet 1985;l: 1222-3.

2. Hunter JB. Menitove JE. HLA antibodies detected by ELISA HTLV-Ill antibody kits. Lancet 1985;2:397.

Date of Filing -October I , 1986

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