Leukemia accounts for around a third of all new cancer cases in children aged between 0-14 years old and can be divided into ALL and AML. An aggressive type of ALL that can be identified by the KMT2A::AFF1 translocation that gives patients especially low survival rate due to resistance of therapies. Cell surface markers such as CD24 can be used to monitor cell differentiation and alter changes in regard of proliferation and development. This is leading to the purpose of the study which is to investigate KMT2A::AFF1 pediatric leukemia and how cell surface CD24 and the cytokines IFN-a and -g may influence progression and maintenance of the cancer. This was made possible by using in vitro cell cultures and analytical multiparameter methods such as flow cytometry. The cell cultures, existing of leukemic cell lines and CRISPR modified induced pluripotent stem cell (iPSC)-derived blood cells, gave insight of different stages of the aggressive ALL. The results showed a proliferation rate drop in cell lines cultured with anti- CD24 blocking antibody and an increase in expression of the cell surface proteins CD38, CD33, and CD24 in iPSC derived blood treated with IFN-g. The conclusion of the study was that CD24 might be a good target for future development of a therapy and that IFN-g could play a role in early leukemic development as seen in genetically modified iPSC-derived blood. But additional research including molecular analyses is required to confirm the results and to obtain further in-depth knowledge within the subject.