Broncho-pneumonia due to measles occurs due to

Bronchopneumonia in MeaslesDirect invasion of T lymphocytes and increased levels of suppressive cytokines, such as IL-4, may play a role in the temporary depression of cellular immunity that accompanies and transiently follows measles.The major infected cell in the blood is the monocyte.Infection of the entire respiratory tract accounts for the characteristic cough and coryza of measles and for the less frequent manifestations of croup, bronchiolitis, and pneumonia.Generalized damage to respiratory tract, with resultant loss of cilia, predisposes to secondary bacterial infection such as pneumonia and otitis media.(Refer: Harrison's Principles of Internal Medicine, 18th edition, pg no: 16000-1603, 1486)