Monocytic Differentiation

Question 1

What are the 3 categories of monocytes differentiation?

Answer 1

• Monoblasts
• Promonocytes
• Monocytes

Question 2

What is the immunophenotype of early and late monoblasts?

Answer 2

• Early monoblast (+): CD34, CD117 and HLA-DR
• Late monoblast: starts to lose CD34 and gains CD4+

Question 3

What are the phenotypic changes that occur with transition to the promonocytes?

Answer 3

• CD117 starts to diminish and CD34 is lost
• Acquire: CD64, CD15, CD11b and CD11c
• Late promonocytes become positive for CD14

Question 4

What markers get expressed more brightly as the promonocytes mature in to monocytes?

Answer 4

• CD11b, CD11c, CD14, CD64, and HLA-DR become brighter as the cells mature

Note: CD14 is expressed most brightly by mature monocytes

Question 5

What marker expression is different in monocytes vs. neutrophils?

Answer 5

• CD11b typically precedes CD15 expression in monocytes in contrast to neutrophils
• HLA-DR expression is retained in monocytes

Question 6

What are mature monocytes in the blood positive for?

Answer 6

(+)
- CD11b, CD11c, CD13, CD14, CD33 and CD64

Question 7

What are the 3 categories of mature monocytes?

Answer 7

• Classical (CD16 neg, CD14 bright+)
• Intermediate (CD16 +. CD14 bright+)
• Non-classical (CD16+, CD14 dim+)

Note: Classical monocytes are 85% of the population in healthy adults.

Question 8

In what conditions can non-classical monocytes be increased in?

Answer 8

• various inflammatory conditions
• malignancies (PCM and AML)

Question 9

What other types of cells do monocytes give rise to?

Answer 9

• tissue macrophages
• osteoclasts (bone)
• Langerhans cells (skin, other)
• Kupffer cells (liver)
• Dendritic cells