For example, during Gram-negative bacterial (E. coli or P. aeruginosa) pneumonia, alveolar neutrophil infiltration is mediated by CD18 or β2 integrin, whereas in Gram-positive bacterial (S. pneumoniae) pneumonia, it is mediated by the CD29 or β1 integrin (48). The gene discussed is ITGB1; the disease is susceptibility to pneumonia measurement.