HLA and tropical sprue.

Area of Science:

• Immunogenetics
• Gastroenterology
• Tropical Medicine

Background:

• Tropical sprue is a malabsorptive condition prevalent in certain tropical regions.
• The etiology of tropical sprue remains incompletely understood, with potential genetic and environmental factors involved.
• Previous research has explored associations between tropical sprue and human leukocyte antigen (HLA) profiles.

Purpose of the Study:

• To investigate the association between HLA antigens and tropical sprue in a Puerto Rican cohort.
• To identify specific HLA alleles that may be linked to the susceptibility or manifestation of tropical sprue.

Main Methods:

• Human leukocyte antigen (HLA) typing was performed on 27 Puerto Rican patients diagnosed with tropical sprue.
• Diagnosis was confirmed by intestinal biopsy and clinical improvement following folic acid treatment.
• A microcytotoxicity assay was employed for HLA antigen determination.

Main Results:

• A significant association was observed between tropical sprue and the presence of at least one antigen from the Aw-19 series (p = 10^-10).
• The Aw-31 antigen showed the strongest association, with a relative risk of 10.6 (p = 1.2 x 10^-6).
• No significant association was found with B-locus antigens or specific haplotypes, suggesting a marker association.

Conclusions:

• The findings indicate a strong genetic predisposition to tropical sprue in Puerto Ricans, linked to specific HLA-A antigens.
• The association with HLA-Aw-31 suggests it may serve as a genetic marker for tropical sprue.
• The lack of B-locus or haplotype association implies the link might be a marker association rather than a direct immune response mechanism.