Immunologists have relied on flow cytometry for the past decades to distinguish specific cell types in heterogenous cell populations (e.g. amount of CD4+ T cells within a blood sample). This is achieved by fluorescent-conjugated antibodies against surface molecules (and also intracellular proteins). With more and more of these fluorescent antibodies available and an increasing number of channels available in the flow cytometers, immunophenotyping is becoming more complex over time.