Molecular studies of DO alleles reveal that JO is more prevalent than HY in Brazil, whereas HY is more prevalent in New York.

Because of the scarcity of anti-Hy and anti-Jo(a), hemagglutination typing for the Dombrock blood group system antigens, Hy and Jo(a), is not feasible. The molecular bases associated with these antigens have been determined, making it possible to distinguish HY and JO from wild-type DO. This provides a tool to predict the probable phenotype of patients and to screen for antigen-negative donors. PCR-RFLP assays and a microchip assay were used to determine the frequency of HY and JO alleles in donors from Brazil and New York. DNA from random Brazilian donors, 288 by PCR-RFLP and 599 by the bead array method (BeadChip, BioArray Solutions, Warren, NJ), was tested to determine 323G/T (HY+/HY-) and 350C>T (JO+/JO-) single-nucleotide polymorphisms. In New York, 27,226 donors who self-identified as being African American were tested by hemagglutination with anti-Gy(a). Nonreactive and weakly reactive samples were tested by PCR-RFLP for the same alleles as listed above. In Brazil, 30 (3.4%) of the samples were JO/DO and 13 (1.4%) were HY/DO. In New York, of the samples that had HY or JO alleles, 14 were homozygous HY/HY 132 were heterozygous HY/DO, 13 were heterozygous HY/JO, 14 were heterozygous JO/DO, and 3 were homozygous JO/JO. These results show that in donors from Brazil, JO (30 alleles) is more than twice as prevalent as HY (13 alleles), whereas in donors from New York, HY (173 alleles) was more than five times more common than JO (33 alleles).

Murine monoclonal antibodies can be used to type RBCs with a positive DAT.

RBCs with a positive DAT due to IgG coating require the use of directly agglutinating reagents or treatment with chemicals to remove sufficient IgG to permit typing of the RBCs with antisera that require use of the IAT. In this study we demonstrate that murine IgG MoAbs to human RBC antigens can be used as an alternative if the anti-mouse IgG is neutralized or affinity purified to prevent cross-reaction with cell-bound IgG. We performed DATs on RBC samples coated with IgG in vivo and in vitro, comparing two anti-human IgG reagents (Organon Teknika, Durham, NC, and Ortho-Clinical Diagnostics, Raritan, NJ) with two affinity-purified anti-mouse IgG reagents (The Binding Site, San Diego, CA, and Sigma, St. Louis, MO), and one non-purified anti-mouse IgG reagent. The affinity-purified anti-mouse IgG reagents were nonreactive with the four in vitro sensitized RBC samples and were nonreactive with 8 of 11 in vivo sensitized RBC samples. Non-purified antimouse IgG and both anti-human IgG reagents reacted with every sample. Use of murine MoAbs to antigen type RBCs coated with human IgG is reliable only when the anti-mouse IgG reagents have been affinity purified or neutralized to prevent cross-reactivity. Our results also show the importance of including a saline/RBC control as well as an anti-mouse IgG/RBC control. Murine MoAbs are valuable reagents and we have applied them successfully in typing patients' RBCs that have a positive DAT.

MIMA-9, a valuable antibody for screening for rare donors.

Since monoclonal antibodies (Mabs) are potentially available in an unlimited volume, they can be used to screen numerous donor blood samples to identify antigen-negative donors. We have used a Mab (MIMA-9) with characteristics that allow for the simultaneous screening of RBCs of any ABO group for high-incidence antigen-negativity in the Kell and Gerbich blood group systems. MIMA-9, a murine IgG2a antibody, previously shown to facilitate the identification of K+k-, Kp(a+b-), K0, McLeod, or Ge:-3 red blood cells (RBCs), was used in MTS gel cards containing anti-mouse IgG as the second antibody to test 1134 K- donors. Among the 1134 donors tested, we found one Kp(a+b-) and one Ge:-2,-3,4 donor. If random donor samples had been used instead of preselecting for K-, we would have expected to identify two K+k- donors. One reagent (MIMA-9) can be used to simultaneously screen for K+k-, Kp(a+b-), K0, McLeod, and Ge:-3 RBCs and thereby conserve rare antisera. Inclusion of anti-mouse IgG in gel cards allowed for rapid screening. MIMA-9 is also a useful reagent to type RBCs with a positive direct antiglobulin test. This antibody is available to donor screening laboratories at no cost for this specific use.

The second example of Lu:-7 phenotype: serology and immunochemical studies.

We describe the second example of red blood cells (RBCs) with the Lu:-7 phenotype in a 37-year-old Latino female (SA). Her RBCs were nonreactive with anti-Lu7 (Mrs. GA) but were reactive with all other antibodies to high-prevalence antigens tested, including those in the Lutheran blood group system. No Lu:-7 RBCs were available for testing. SA's serum was nonreactive by the indirect antiglobulin test against (1) recessive and dominant Lu(a-b-) RBCs and (2) trypsin-treated or a-chymotrypsin-treated RBCs of common phenotype. By immunoblotting, eluates containing anti-Lu7 from both Mrs. GA and SA reacted with apparently the same bands in RBC membranes of common phenotype as did human anti-Lub, reacted weakly with Lu(a-b-) RBCs of the dominant type, and were nonreactive with SA's RBC membranes. These findings raise the Lu7 antigen from its Lutheran-related (para-Lutheran) status to a bona fide member of the Lutheran blood group system.