HLA-DR specific monoclonal antibodies block lymphoproliferative response to measles vaccine in vitro: a pilot study

Humoral and cell-mediated immune responses are important in protection against measles. Non-response to vaccination has been associated with specific HLA-DR and HLA-DQ alleles; however, little is known about the relative importance of these alleles in the cellular immune response induced by measles virus vaccine. To investigate the role of HLA-DR/DQ class II restriction, a small pilot study was conducted. Lymphoproliferation assays using class II DR and DQ-specific monoclonal antibodies (MoAb) were performed at one week and two weeks post immunization with MMRII vaccine. The mean stimulation index (SI) was 4.4 and 5.3 at one and two weeks with reductions in SI of 47.6% and 70.2%, respectively, following the addition of DR-specific MoAb (p<0.001). These results clearly show that a significant proportion of the cell-mediated immune response to measles virus vaccine, as measured by SI, is HLA-DR restricted.