The detection of two serologically distinct HLA-A28 specificities

Area of Science:

• Immunogenetics
• Human Leukocyte Antigen (HLA) system
• Population genetics

Background:

• The Human Leukocyte Antigen (HLA) system plays a crucial role in immune response and transplantation.
• HLA-A28 is a known HLA allele with diverse antigenic specificities.
• Understanding HLA allele variations is vital for population genetics and personalized medicine.

Purpose of the Study:

• To characterize a newly identified specificity within the HLA-A28 allele using serum 9045.
• To investigate the association of this specificity with other HLA loci, specifically HLA-B14.
• To explore the ethnic distribution and potential origins of different HLA-A28 molecular populations.

Main Methods:

• Serological analysis using serum 9045 on a mixed population (American Blacks, Jewish Caucasians, non-Jewish Caucasians).
• Typing for HLA-A28 and HLA-B14 to determine associations.
• Antigenic comparison of identified HLA-A28 subsets with known public determinants.

Main Results:

• Serum 9045 detected a subset of A28 cells (termed A28.2) preferentially in American Blacks and Jewish Caucasians, but not in non-Jewish Caucasians.
• The A28.2 specificity demonstrated a strong association with HLA-B14.
• A28 positive, 9045 negative cells (A28.1) did not show this association and appear more prevalent in Northern European Caucasians.
• A28.2 determinants were antigenically similar to A28.1 but distinct from other shared public determinants.

Conclusions:

• HLA-A28, as defined by common antisera, likely represents at least two distinct molecular populations.
• The A28.2 form may have originated in the Mediterranean basin.
• The A28.1 form appears more common in individuals of Northern European ancestry.