Taking into account this scientific background the aim of our study was: (i) to investigate the role of the SNPs in the genes of proinflammatory cytokines (IL6, IL1B, IL8), antiinflammatory cytokines (IL10, IL4, IL13) and toll-like receptors TLR2, TLR4 and TLR9 in CAP and HAP patients, (ii) to combine existent knowledge and our own experimental data on the above genes in a series of meta-analyses of genetic susceptibility to pneumonia development and outcome. The gene discussed is IL4; the disease is pneumonia.