Frequency of HLA class II DR and DQ antigens in Brazilian patients with type I diabetes

Abstract

The association of type I diabetes mellitus with genes of the HLA class II system has been well established. These genes may be different among populations due to the genetic background predominating in each ethnic group. The objective of the present study was to characterize HLA class II antigens in a Brazilian population of type I diabetics. The study was conducted on 58 diabetic patients and 102 healthy controls of the same geographic area and of similar ethnic background. B lymphocytes were separated from total lymphocytes by nylon wool.HLA antigens were typed by a complement-dependent microlymphocytotoxicity method. Data were analyzed statistically by the two-tailed exact Fisher test. The frequencies of HLA-DR3 and - DR4 antigens, and of the combinations of HLA-DR3/DR4 antigens were significantly higher in diabetics than in controls (P < 0.05). The frequencies of the HLA-DQ2 and DQ3 antigens did not show significant differences when analyzed separately; however, the combinations of HLA-DR3 and HLA-DQ3, HLA-DR4 and HLA-DQ2 or HLA-DQ3, and HLA-DR3 HLA-DR4 and HLA-DQ3 antigens were significantly higher in the diabetic group than in the control (P < 0.05). Even though HLA-DR2 and -DR7 antigens (associated with protection against the disease) were less frequent than in the control group, no significant difference was detected after P correction.