IGKV1D-22 and infection: Importantly, the S100a8/a9 protein levels steadily increased over time in the S. aureus Newman-infected knee joints of mice (Figure 5C) with a median value ranging from 3.415 on day 1 to 18.05 on day 3 and 26.48 on day 9 after infection, as compared to 0.6361 in healthy controls.