139-P

Abstract

Aim The HLA-B ∗ 37:02 allele was first described in 1995 in a Syrian father and one of his sons during routine HLA typing. It has no assigned serologic equivalent and a mixed B27 and B37 serologic reactivity pattern has been suggested. In this report we characterize the serological reactivity and possible haplotypes association observed with this allele. Methods Of 73,355 subjects HLA typed in our laboratory, 644 were positive for B ∗ 37 with only 2 positive for B ∗ 37:02. One subject is an unrelated bone marrow donor and the other is a subject from the international cell exchange. The serological reactivity of both cells and probable haplotypes were analyzed. Results The serological reactivity were similar for both cells with BW4 positivity. Both cells reacted positively to polyspecific sera with B ∗ 37, B ∗ 27, and B ∗ 47 reactivity. Interestingly, neither of the cells reacted to operationally monospecific sera with B27, B37, or B47 reactivity or to polyspecific sera with B27 and B37 reactivity. No polyspecific sera with B37 and B47 reactivity were available for testing. A population genetics approach based on reported haplotypes frequencies suggest that the most probable haplotypes for both cells are A ∗ 24:02 B ∗ 18:01 C ∗ 05:01 DRB1 ∗ 03:01 & A ∗ 01:01 B ∗ 37:02 C ∗ 02:02 DRB1 ∗ 11:04 for the first cell and A ∗ 29:02 B ∗ 14:02 C ∗ 0202 DRB1 ∗ 07:01 & A ∗ 30 B ∗ 37:02 C ∗ 02:02 DRB1 ∗ 13 for the second cell. The former haplotype is similar to that of the first described B ∗ 37:02 allele. Conclusions This analysis emphasizes the value of serologic HLA typing methods in characterizing newly described and uncommon HLA alleles.