Rl. Sepulveda et al., EFFECT OF HUMAN NEWBORN BCG IMMUNIZATION ON MONOCYTE VIABILITY AND FUNCTION AT 3 MONTHS OF AGE, The international journal of tuberculosis and lung disease, 1(2), 1997, pp. 122-127
SETTING: Immune response induced by BCG vaccination seems to reflect t
he development of T-cell immunity and monocyte activation. Participant
s were recruited from a large prospective study in infants from a subu
rb in Santiago, Chile. OBJECTIVE: To determine whether newborn BCG imm
unization changes the innate ability of cultured monocyte-macrophages
to ingest and kill virulent mycobacteria in the absence of lymphocytes
. DESIGN: The study population consisted of 15 three-month-old, tuberc
ulin-positive infants immunized with BCG (Japanese) at birth, 13 rando
mly-selected, age-matched tuberculin-nonreactive infants in whom BCG i
mmunization was postponed until one year of age, and five BCG-immunize
d, tuberculin-reactive adults. Adherent cells were cultured for 48 h.
Monocyte-macrophage viability and number and viability of intracellula
r Mycobacterium tuberculosis bacilli were assessed after an additional
2 h and 4 and 7 days of incubation. RESULTS: There was no difference
in the mean number of adherent cells present after 48 h among the thre
e study groups. Adherent cells from BCG-immunized infants and adults h
ad a significantly higher viability after 7 days in culture than adher
ent cells from non-immunized infants. The percentage of cells ingestin
g h?. 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 ki
lling of mycobacteria by cells from immunized infants and adults. CONC
LUSION: These results suggest that BCG vaccination increases monocyte
viability and the uptake of M. tuberculosis without enhancing the abil
ity to kill ingested M. tuberculosis in the absence of lymphocytes.