Development of allergy to laboratory animals is associated with particular Gm and HLA genes

To find out whether IgG genes are involved in atopy we studied 26 of 101 laboratory technicians who had developed laboratory animal allergy (LAA). The genes for the constant region of the heavy chains of IgG subclasses were analyzed by serum Gm allotypes, representing products on allelic level of the IGHCG1, IGHCG2 and 1GHCG3 on chromosome 14q32. There was a significantly increased frequency of-the Gm(f,f;n,n;b,b) genotype (57.7 instead of 22.3%, p<0.001) representing IgG1, IgG2 and IgG3 molecules and in particular increased frequency of Gm genotypes with the homozygous expression of G2m (n,n) (69.2 instead of 27.4%, p<0.001) and of the Gm(f,n,b) haplotype (75 instead of 44.8%, p <0.001) compared to a normal Caucasian population. An increased HLA-DR4 content of the LAA group (61.5 instead of 33.7%, p<0.01) was further investigated for Gm allotypes. Among 16 HLA-DR4 LAA individuals, the Gm(f,f;n,n;b,b) genotype (56.3 instead of 22.3%, p<0.01) and the Gm genotypes with the homozygous expression G2m(n,n) (62.6 instead of 27.4%, p<0.01) dominated. However, the HLA-DR4 frequency among Gm(f,f;n,n;b,b) of I,AA patients did not deviate from the frequency of healthy individuals of the same Gm genotype. The increased frequency of HLA-DR4 antigen in LAA patients might be due to its association to the Gm(f,f;n,n;b,b) genotype. This study supports the following concept: the susceptibility of developing LAA is associated with Gm allotypes Glm(f) expressed from IGHCGl, G2m(n) from IGHCG2 and G3m(b) from IGHCG3 on both alleles situated close to IGHCE on chromosome 14q32. The association of LAA to Gm allotypes [Gm(f,f;n,n;b,b)] expressed from chromosome 14q32 and of HLA class II antigens (HLA-DR4) expressed from chromosome 6P21.3 further confirms the polygenic inheritance of the immune response in atopy.