Human immune responsiveness to Lolium perenne pollen allergen Lol p III (rye III) is associated with HLA-DR3 and DR5.

A well-characterized allergen of Lolium perenne (perennial rye grass) pollen, Lol p III, has been used as a model antigen to study the genetic control of the human immune response. Associations between HLA type and IgE or IgG antibody (Ab) responsiveness to Lol p III were studied in two groups of skin-test-positive Caucasoid adults (N = 135 and 67). We found by nonparametric and parametric analyses that immune responsiveness to Lol p III was significantly associated with HLA-DR3 and DR5. No association was found between any DQ type and immune responsiveness to Lol p III. Geometric mean IgE or IgG Ab levels to Lol p III were not different between B8+, DR3+ subjects and B8-, DR3+ subjects, showing that HLA-B8 had no influence on the association. Lol p III IgG Ab data obtained on subjects after grass antigen immunotherapy showed that 100% of DR3 subjects and 100% of DR5 subjects were Ab+. A comparison of all the available protein sequences of DRB gene products showed that the first hypervariable region of DR3 and DR5 (and DRw6), and no other region, contains the sequence Glu9-Tyr-Ser-Thr-Ser13. Our observations are consistent with the possibility that immune responsiveness to the allergen Lol p III is associated with this amino acid sequence in the first hypervariable region of the DR beta 1 polypeptide chain.