Ischemic stroke is one of the leading causes of death in the world. There currently only two FDA approved treatments for ischemic stroke, tissue plasminogen activator (tPA), and mechanical thrombectomy. Leukemia inhibitory factor or LIF, has been shown to improve functional recovery in young rats put under ischemic stroke conditions, but neither the responses of older rats or the gendered rat differences in immune responses have yet been tested with LIF. The purpose of this study is to identify the differences in immune cell infiltration of aged male and female rats subjected to MCAO and treated with LIF. For his study, the rats were subjected to either MCAO surgery or sham surgery, and given an injection of either LIF or PBS at 6, 24, and 48 hour time points after surgery. At the 72h time point the rats had MRI scans done on their brains immediately before euthanisia, and brains, blood, and spleens of the rats were collected for flow cytometry analysis. The spleen, blood, and brain samples were stained and analyzed with a flow cytometer for counts of Macrophages and Monocytes, B cells, and CD4 and CD8 T cells, and the resulting data was compiled using FlowJo and visualized using GraphPad. Results show that while there are some potential differences in the immune cell infiltrations of male vs female rats and PBS vs LIF rats, the deviation in sample levels of immune cells is on high for statistically significant conclusions to be made. A larger sample size for each group (currently n≤4 per treatment group) would be needed in a future study to investigate his further.Support or Funding InformationKY‐WV Louis Stoke Alliance For Minority Participation (NSF #1826763), ASPET SURF Program at the University of Kentucky