M. Raes et al., PERIPHERAL-BLOOD T-LYMPHOCYTE AND B-LYMPHOCYTE SUBPOPULATIONS IN INFANTS WITH ACUTE RESPIRATORY SYNCYTIAL VIRUS BROCHIOLITIS, Pediatric allergy and immunology, 8(2), 1997, pp. 97-102
Most data concerning immunopathogenetic mechanisms involved in respira
tory syncytial virus (RSV) infection are derived from animal studies.
In infants with RSV bronchiolitis the target organ i.e. the airway is
hard to explore. We looked for specific alterations in peripheral bloo
d lymphocyte subpopulations in infants hospitalized for RSV bronchioli
tis. Flow cytometric analysis with a large panel of monoclonals was pe
rformed on peripheral blood lymphocytes in thirty-two infants (mean ag
e: 4.9 months) admitted for RSV bronchiolitis. Data collected on admis
sion were compared with age-matched control values and also with resul
ts obtained at the end of the first week of hospitalization. Differenc
es between age-groups (older or younger than 4 months) and between cli
nical subgroups (clinical severity score more or less than 6) were loo
ked for. In the group of infants as a whole, regardless of age and cli
nical score the number of CD4+ cells on admission was significantly el
evated compared to normal values for age (p < .0001) including a high
fraction of the naive suppressor-inducer subpopulation (CD4+/CD45RA+)
and a low fraction of the reciprocal memory helper-inducer subpopulati
on (CD4+/CD29+). Within the CD8+ cell population the number of T cells
with cytotoxic activity (CD8+/S6F1+) was significantly elevated (p <
.0001) as were other types of cytotoxic cells. A significant decrease
(p < .0001) in the proportion of the precursor/suppressor-effector sub
population (CD8+/S6F1-) was seen. Absolute numbers and percentages of
CD19+ B cells were significantly elevated (p < .0001) with a significa
nt increase in the CD5+ subfraction (p < .0001) as well as in the CD10
+ subfraction (p < .0001). In the older age group immunophenotypic cyt
otoxicity was more pronounced with increased clinical score. During re
recovery the CD45RA+:CD29+ ratio tended to normalize within the CD4T cells. Within the B lymphocyte subsets significant increase in the C
D19+/CD5+ fraction (p < .05) was seen. We conclude that there are sign
ificant changes in the number of peripheral blood lymphocyte subsets i
n infants with RSV bronchiolitis as compared to age-related controls.
We hope that present data could be useful in further exploration of RS
V immunology in humans. A possible link between RSV bronchiolitis and
the subsequent development of atopy is mentioned.