Recent collaborative Center efforts have led to interesting findings with respect to gene-environment interactions and a publication in Lancet, "Effect of glutathione-S-transferase M1 and P1 genotypes on xenobiotic enhancement of allergic responses: randomised, placebo-controlled crossover study." This study demonstrated that individuals with GSTM1 null or the GSTP1 I105 wildtype genotypes showed greatly enhanced nasal allergic responses in the presence of diesel exhaust particles (Gilliland et al. 2004). Compared with patients with a functional GSTM1 genotype, GSTM1 null patients had a significantly larger increase in IgE and histamine after diesel exhaust particles plus allergen nasal challenge. The I105 GSTP1 genotype was associated with an increase in IgE and histamine after challenge with diesel exhaust particles and allergens. The diesel exhaust particles enhancement was largest in patients with both the GSTM1 null and GSTP1 I/I genotypes. This paper demonstrated that GSTM1 and GSTP1 modify the adjuvant effect of diesel exhaust particles on allergic inflammation.