54 Abstracts

#19 4.3

DQA AND DRB ANALYSIS IN MEXICAN CONTROLS AND LEISHMANIASIS PATIENTS BY

PCR AMPLIFICATION. H Debaz, V Trejo and C Gorodezky. Dept. of Immunoge-

netics, INDRE, SSA. Mexico D.F. MEXICO.

The most common form of leishmaniasis in Mexico is the localized cuta neous (LCL) which appears as an ulcerative lesion on the skin and shows an intact specific cellular immune response. The genetics of LCL in mi- ce has been widely analyzed but until the 5WLAT, very few data existed

in man. A group of 65 LCL patients and 25 controls all of them Mexican

Mestizos were studied at the molecular level, because we suggested at

the 5WLAT a serological DRwII-DQw3 association. Protocols, primers and

probes were kindly donated by Dr. Henry Erlich. DNA was extracted from

leukocytes and PCR amplification was done using iug of DNA, 20 pmoles of each primer (GH26 and GH27 for DQA; GH46 and GH50 for DRB), 25mM of

dNTP's and 2.5U of Taq DNA polymerase. The reactions were amplified ma-

nually for 30 cycles (denaturation: 95°C for 30 sec. Annealing: 55°C

for 30 sec. Extention: 72°C for 60 sec.) The last i0 cycles were exten-

ded to 60 sec. for annealing and 120 sec. for extention. Eight HRP-oli- gonucleotide probes which typed for DQAI,2,3,4,1.1,1.2,1.3 and one for

DRB (DR5) were used for typing. DNA was spoted onto nylon membranes and

was hybridized at 42°C for types and at 55°C for subtypes and for DR5.

Tetramethylbenzidine was used for color development. No statistical di-

fferences were detected between the two groups among DQA alleles or for

DR5. These results suggest that if there is a susceptibility gene with- in the HLA region, it should be in linkage with DQB or other class II genes. The prevalent DQA alleles in these mestizos are DQAI.I,DQA3 and

DQA4. Between 2 and 6% of DQAI cases could not be assigned to DQAI sub- types, suggesting perhaps a new split. Finally, some unusual hap]otypes

were observed, such as, DR7-DQA3, DRI-DQA4, DR4-DQAI.I, DRw8-DQAI.3.

#20 4.3

HLA CLASS II ALLELE FREQUENCIES IN AFRICANS. AVS Hill, CEM Allsopp,

D Kwiatkowski, ME Molyneux, AJ McMichael, BM Greenwood. Institute of Molecular Medicine, Oxford, UK; MRC Laboratories,

Fajara, The Gambia; Liverpool School of Tropical Medicine, UK.

Using a combination of RFLP typing and oligonucleotide

hybridization we have determined HLA class II allele frequencies in over 2000 Africans from the Gambia in West Africa and Malawi in

central Africa. Using a single restriction enzyme, Taq I, and

sequential hybridization with DRB and DQB probes a remarkable

diversity of RFLP patterns was found. 44 patterns were seen in

Africans compared to only 25 in Caucasians. Despite this

heterogeneity a single DRB RFLP pattern shared by DRwll and the

recently described DRBI*I304 allele is found in 48% of Gambians.

Several "Black" DR haplotypes show characteristic Taq I DRB band patterns including, DRwll-52d (haplotype frequencies: 5% in the

Gambia, 12% in Malawi), DRwI8-DRw52c (1%,2%), DRwlI-DRw52c (1%,0%),

DRw12-Dw52a (0%,2%), as well as additional DR4 and DR9 patterns. Similarly, DR-DQ linkage arrangements rare or absent in other populations, are found: DRwlI-DQw2, DRwlI-DQw5, DRwlI-DQw6, DRwI2-

DQw5, DRwI3-DQw2, DRwI3-DQw5, DRwI3-DQw7, DRwI8-DQw4. The 3.7kb Taq

I DQB band which identifies the DQBI*0201-DQAI*0301 arrangement (absent in Europeans) was found at an allele frequency of 7% and was

linked to the majority (66%) of DR7/DR9 alleles but <1% of DRwll

alleles. Some alleles showed marked frequency differences between the two regions: the carrier rates of DRwI0 and DRwI5 were 16% and 1.5%

in the Gambia, but 2% and 26%, respectively, in Malawi. These data indicate that, although African have a distinctive and remarkably

diverse set of HLA class II types, considerable variation in frequencies is found between different areas.