Typing for HLA‐D/DR Associated DP‐Antigens with the Primed Lymphocyte Typing (PLT) Technique

Abstract

A total of 74 healthy unrelated random individuals and 36 patients with juvenile rheumatoid arthritis (JRA) were typed for HLA‐D antigens with the homozygous typing cell technique and typed for HLA‐D/DR associated DP‐antigens with the primed lymphocyte typing (PLT) technique. All patients and some of the controls were also HLA‐DR typed with a limited battery of anti‐DR sera. Selected PLT‐cells, specific for the HLA‐D/DR antigens D/DRwl‐8 and the local specificity D “H” were used. The results of the PLT‐experiments were evaluated with the Normalized Median Response (NMR) method and the further procedure of DP‐antigen assignment was analyzed. The DP‐antigen assignments could be done solely according the NMR‐values in approximately two thirds of the individuals. In the remaining individuals, further interpretation of the experimental data had to be done for the assignment of DP‐antigens. The correlation coefficients were estimated between the HLA‐D assignments and (i) the individual PLT‐cell NMR‐values with a fixed cut‐off for positive reactions and (ii) the DP‐antigen assignments. These coefficients were 0.79 and 0.92, respectively. The correlations between HLA‐D, ‐DR and DP‐antigen assignments of the specificities HLA‐D, ‐DR and DPI, 2, 3, 4, 7 and 8 were analyzed in 42 controls and 36 JRA patients. The total correlation coefficients were: (i) HLA‐D/DR: r = 0.78; HLA‐DR/DP: 0.77; and HLA‐D/DP: 0.96. The DP‐antigen assignments correlated significantly better with HLA‐D than with the HLA‐DR antigen assignments, which does not agree with other studies. The DP‐antigen frequencies among the controls were calculated and the estimated sum of gene frequency corresponding to definable DP‐antigens was 0.94 indicating that about 12% of random individuals possess as yet undefined DP‐antigens.