Capillary density in developing and healing tuberculous lesions produced by BCG in rabbits. A quantitative study

Area of Science:

• Immunology
• Dermatology
• Vascular Biology

Background:

• Tuberculosis (TB) is a significant global health issue.
• Understanding the host response, particularly vascular changes, is crucial for TB pathogenesis and treatment.

Purpose of the Study:

• To quantitatively assess capillary density in dermal tuberculous lesions.
• To investigate the relationship between vascular changes, lesion development, and immune response in TB.

Main Methods:

• Dermal tuberculous lesions were induced in rabbits using Bacillus Calmette-Guérin (BCG) injection.
• Capillary density was measured using a colloidal carbon perfusion technique and microscopy in non-necrotic granulation tissue.
• Comparison of capillary density between normal skin and BCG-induced lesions.

Main Results:

• Capillary density increased by 60% in non-necrotic BCG lesions compared to normal skin (6.1 vs. 3.8 mm/sq mm).
• Capillary density remained relatively constant during lesion growth and regression.
• Vascular changes in tuberculin reactions mimicked those in BCG lesions.

Conclusions:

• BCG lesions exhibit significant angiogenesis, with the capillary network supporting defense cells.
• The enhanced vascularization is crucial for the emigration of mononuclear phagocytes and lesion healing.
• The study provides insights into the vascular dynamics of dermal tuberculosis.