Lymphocytes are agranulocytes $WBC$, which exist in two forms i.e., $B-$lymphocyte and $T-$lymphocytes and these are responsible for immune response of the body.
Erythrocytes : These are also known as $RBC$, which help in gaseous transportation i.e., $O_{2}$ and $CO_{2}$.
Thrombocytes : These are also called platelets and are formed from the megakaryocytes (large cells of bone marrow).