Deciphering decidual leukocyte traffic with serial intravascular staining

Area of Science:

• Reproductive Immunology
• Maternal-Fetal Interface
• Immunological Research

Background:

• The maternal decidua undergoes significant immune cell composition changes throughout gestation.
• Understanding leukocyte migration dynamics between the decidua and systemic circulation is crucial but remains poorly understood.

Purpose of the Study:

• To investigate the degree, timing, and subset-specific nature of leukocyte traffic into the decidual basalis during pregnancy.
• To evaluate serial intravascular staining as a method for assessing leukocyte migration in vivo.

Main Methods:

• Intravascular staining using labeled αCD45 antibodies in pregnant C57BL/6J mice and cynomolgus macaques.
• Analysis of decidual cells via flow cytometry following timed infusions of labeled antibodies.
• Examination of decidual tissue sections to visualize labeled cells.

Main Results:

• In mice, the proportion of intravascularly-negative leukocytes decreased, while recent immigrants increased during mid- to late-gestation.
• In macaques, shorter infusion times (5 min) resulted in a higher proportion of intravascularly-positive cells compared to longer times (2 hr).
• Labeled cells were observed within decidual tissue, near blood vessels and deeper in the stroma.

Conclusions:

• Decidual leukocyte traffic is dynamic and changes across gestation.
• Serial intravascular staining is a sensitive and valuable tool for defining leukocyte migration into the decidua during pregnancy.