In leucopenia, which cell type is predominantly involved?
Leucopenia  
The absolute granulocyte count is particularly low (below 1500/µl) with relative lymphocytosis. The neutrophils are morphologically normal, but their alkaline phosphatase score is high.
Reference:  Textbook of Pathology, Harsh Mohan, 7th ed page no 302
Erythrocytes
Granulocytes
Eosinophils
Monocytes