Phagocytosis of TB bacilli does not occur because of -
Virulent strains of tubercle bacilli form microscopic "serpentine cord" in which acid fast bacilli are arranged in parallel chains, cord formation is correlated with virulence. A "cord factor" has been extracted from virulent bacilli with petroleum ether. It inhibits migration of leukocytes, causes chronic granulomas, and can serve as an immunologic "adjuvant"
Wax D
Muramyl dipeptide
Cord factor
Peritrichate Cilia