Polymorphisms of the Ig heavy chain 3′ Regulatory Region associates with humoral Ig Homeostasis

Aim. Incomplete maturation of immune system in the first years of life could affect different individual response to vaccination. To investigate the issue we studied a polymorphic genomic cis regulator of Ig heavy chain in response to vaccination with viral antigens. Method. Two cohorts of healthy subjects, one not yet 3 years and a second between 21 and 26 years old were vaccinated against H1N1, H2N3, B and HBV antigens respectively. From time zero the two cohorts were followed up for the total peripheral blood levels of Ig and for specific antibodies against the vaccine antigens. Subjects were genotyped for Ig heavy chain 3’ RR structural polymorphisms of enhancer hs1.2. Results. The serum specific antibodies in subjects Non responder, Responder and High responder to the vaccination is not associated with the levels of circulating IgM, IgG, IgA. However, the humoral concentration of Ig in the adult subjects correlates with hs1.2 allelic frequency as observed previously (p<0.001). Children with low IgM concentration versus children with high IgM show a change of hs1.2 allele *1 frequency from 47% to 1.8% and for allele *2 from 43% to 82% (p<10-9). The number of CD19 and CD27 cells were determined. Conclusions. The hs1.2 enhancer is associated with regulation of Ig levels. Children with allele *2 could have a possible advantage with wider repertoire of Ig. We suggest different controls for the production and mantainment of total and specific Ig amount with vaccination.