A serum facted by newborn calf serum

Area of Science:

• Immunology
• Hematology

Background:

• Newborn calf serum (NBCS) induces an inflammatory reaction in mice.
• This reaction is characterized by increased peritoneal macrophages and peripheral blood monocytosis.

Purpose of the Study:

• To investigate the presence and nature of a monocytosis-inducing factor in the serum of mice injected with NBCS.
• To determine the specificity and characteristics of this factor.

Main Methods:

• Intraperitoneal injection of NBCS into mice.
• Collection and intravenous injection of serum (CalS18, CalS24) from treated mice into test mice.
• Analysis of blood cell counts (monocytes, promonocytes, lymphocytes, granulocytes).
• Ultrafiltration of active serum to estimate molecular weight.

Main Results:

• Serum from mice 18-24 hours post-NBCS injection induced monocytosis in test mice.
• This effect was specific to mononuclear phagocytes.
• The active factor increased promonocyte and bone marrow monocyte numbers, suggesting enhanced monocyte production.
• The factor's molecular weight is below 50,000 Daltons and distinct from the NBCS-derived factor.

Conclusions:

• A transient monocytosis-inducing factor is generated in mouse serum following NBCS administration.
• This factor stimulates monocyte production and is specific for the mononuclear phagocyte lineage.
• The factor's characteristics suggest it is a novel mediator distinct from the initial inflammatory trigger.