A kit for in vitro or ex vivo measurement of sCD127 expression in a biological sample, the kit including: specific tools or reagents allowing measurement of sCD127 expression in said biological sample; and a positive standard sample which is a sample calibrated to contain an amount of sCD127 which corresponds to the mean amount measured in a pool of samples from patients who are known to have developed a nosocomial infection, and/or a negative standard sample which is a sample calibrated to contain the amount of sCD127 which corresponds to the mean amount measured in a pool of samples from patients who are known not to have developed a nosocomial infection.