Severe hypertension in the Spanish population. Association with specific HLA antigens.

There is now increasing evidence for immunological changes in essential hypertension. Immunological response is determined in part by genes linked to the HLA system. It has been reported a positive association between HLA B15 and the risk for cerebral events in essential hypertensive (EH) patients. We studied the distribution of HLA antigens in 128 EH (age range, 13-85 years) and 1000 normotensive controls. EH were classified in accordance with the World Health Organization (WHO) criteria: in WHO Stages I and II, there were 100 patients; in WHO Stage III, there were 28 patients. HLA-A and B antigens of peripheral blood lymphocytes were studied according to the microlymphocytotoxicity test. The results were compared by chi-square analysis, and the p value was multiplied by the number of antigens studied at each locus, to avoid overestimation of an association. Frequency of HLA-BW 22 was higher in EH compared with controls (5.4% vs 1.2%, p less than 0.01). Frequency of HLA-B12 in EH with WHO Stage III hypertension (64.2%) was significantly increased compared either with EH in WHO Stage I or II (29%, p less than 0.01) or the control group (26.9% p less than 0.001). The incidence of HLA-B15 antigen in the whole hypertensive group was 3.1%, lower than in normotensive controls (6.4%, p less than 0.8). None of the patients with WHO Stage III hypertension had the HLA-B15 antigen. In conclusion, the results seemed to indicated that the Spanish population had an association between HLA-B12 and severe hypertension.