The key cell types involved in the acquired immunity include all EXCEPT:
B lymphocytes
Erythrocytes
T lymphocytes
Antigen presenting cells (APC)
The main physiological role of red blood cells (RBCs), or erythrocytes is to transport gases (O2, CO2) from the lung to the tissues and to maintain systemic acid/base equilibria. 
In addition, RBCs are well equipped with antioxidant systems, which essentially contribute to their function and integrity.
They are not involved in acquired immunity.