The use of receptor protein candidates such as Klebsiella pneumoniae iron-regulated outer membrane protein [42], Acinetobacter baumannii iron-regulated outer membrane protein [43], Streptococcus pneumoniae pneumolysin [44], in the diagnosis of pneumonia is justified because they are produced in relatively high amount inside body fluid across all strains and subtypes of these pathogens; do not change with time; highly accessible either as cell surface receptor and relatively stable in a mild in vitro handling. These receptors were therefore retained for further analysis. Here, CD177 is linked to susceptibility to pneumonia measurement.