Loss of interleukin-2 requirement for the generation of T colonies defines
an early event of human T-lymphotropic virus type I infection
M Duc Dodon and L Gazzolo
Accessory cells and/or soluble factors, together with interleukin 2 (IL2),
are required for the proliferation and differentiation of
phytohemagglutinin (PHA)-activated T lymphocytes. Human T-lymphotropic
virus, type I (HTLV-I), a human retrovirus isolated from patients with
adult T cell leukemia, can transform T cells in vitro. We investigated the
role of HTLV-I-transformed T cell lines as accessory cells in promoting the
growth of T colony-forming cells. We found that T cells isolated by E
rosetting and then activated with PHA, when seeded with as few as 5 X 10(3)
irradiated HTLV-I-producing cells, could generate colonies in the absence
of IL2. We analyzed further the effects of HTLV- I virions on T colony
formation. Infection of T cells with semipurified HTLV-I viral particles
promoted colony formation, in the absence of IL2, of accessory cells or
soluble factors. The same results were obtained either with
monocyte-depleted T lymphocytes, or with T4 or T8 lymphocytes. Furthermore,
T lymphocytes in the presence of heat- inactivated HTLV-I (devoid of
replicative potential) could form colonies independently of IL2. Finally,
experiments with sera positive for HTLV-I antibodies (to abolish binding of
viral particles to cellular receptors) indicated that HTLV-I promoted
IL2-independent colony formation, only by "touching" T colony-forming
cells. These results taken together demonstrate that the loss of the
exogenous IL2 (and other growth-helping factors) requirement defines an
early event of HTLV-I infection. The results also suggest that viral
attachment to T cells possibly supplies an accessory function triggering
autocrine secretion of IL2 by these cells.
Volume 69,
Issue 1,
pp. 12-17,
01/01/1987
Copyright © 1987 by The American Society of Hematology
