HLA Class II Loci and Malaria Infection in Thailand

The association of variation at the HLA class II loci DQAl, DQBl, DRBl and DPBl with malaria infection and antibody titers was studied in two endemic populations, Trat and Pongnamron, in Thailand. Presence of P. falciparum was determined by microscopy and PCR. Significant allele frequency differences were found between infected and uninfected individuals for two alleles in the sample from Trat collected in 1991, while an independent sample from the same locality in 1994 did not show any association. A set of 10 families from Pongnamron were studied for infection status and the antibody titers against the whole parasite (PARIF) and against the P. falciparum membrane antigen (Pf155/RESA) (EMIF) were measured. Using the TDT test significant deviation from equal probability of transmission of parental HLA alleles was detected only for the DPB1*0202 allele and the antibody response to the whole parasite. Due to the large number of tests performed we cannot exclude that the significances observed represents statistical type I errors. Thus, the results do not provide evidence of an involvement of HLA class II loci in either malaria infection or response versus the two malaria antigens in the two Thai populations.