MHC-I molecules are the principal self ligands that bind to inhibitory receptors on Natural killer cells. During erythropoiesis, HLA-A, -B and -C expression disappears but no information is available on HLA-E and HLA-G expression. Moreover, old reports state that expression of CD235a on red blood cells and their precursors confer protection from NK cell-mediated cytotoxicity. Consequently, the aim of the present study was to examine HLA-E, -G, and CD235a expression using an in vitro erythropoiesis model and bone marrow aspirates. In parallel, the expression of CD36, HLA-ABC, and CD71 was analyzed. To conclude, this thesis confirm the findings of previous studies for these markers. In addition, HLA-E and HLA-G were shown to be weakly expressed, thus it is unlikely that they play a role in NK regulation by RBCs. Furthermore, the implication of glycophorin A in NK cell regulation needs to be elucidated.