• R L Sepulveda, S Arredondo, E Rodriguez, B Gonzalez, L E Leiva, and R U Sorensen.
• National Institute of Respiratory Diseases and Thoracic Surgery, University of Chile Medical School, Santiago, Chile.
• Int. J. Tuberc. Lung Dis. 1997 Apr 1; 1 (2): 122-7.

SettingImmune response induced by BCG vaccination seems to reflect the development of T-cell immunity and monocyte activation. Participants were recruited from a large prospective study in infants from a suburb in Santiago, Chile.ObjectiveTo determine whether newborn BCG immunization changes the innate ability of cultured monocyte-macrophages to ingest and kill virulent mycobacteria in the absence of lymphocytes.DesignThe study population consisted of 15 three-month-old, tuberculin-positive infants immunized with BCG (Japanese) at birth, 13 randomly-selected, age-matched tuberculin-nonreactive infants in whom BCG immunization was postponed until one year of age, and five BCG-immunized, tuberculin-reactive adults. Adherent cells were cultured for 48 h. Monocyte-macrophage viability and number and viability of intracellular Mycobacterium tuberculosis bacilli were assessed after an additional 2 h and 4 and 7 days of incubation.ResultsThere was no difference in the mean number of adherent cells present after 48 h among the three study groups. Adherent cells from BCG-immunized infants and adults had a significantly higher viability after 7 days in culture than adherent cells from non-immunized infants. The percentage of cells ingesting M. tuberculosis and the number of bacilli per cell after 2 h and 4 days was significantly higher in immunized infants and adults than in non-immunized infants. However, there was no evidence for increased killing of mycobacteria by cells from immunized infants and adults.ConclusionThese results suggest that BCG vaccination increases monocyte viability and the uptake of M. tuberculosis without enhancing the ability to kill ingested M. tuberculosis in the absence of lymphocytes.

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