Anti-lymphocyte globulin stimulates normal human T cells to proliferate and
to release lymphokines in vitro. A study at the clonal level
GC Barbano, A Schenone, S Roncella, R Ghio, A Corcione, PG Mori, M Ferrarini and V Pistoia
Servizio di Immunologia Clinica, Istituto Nazionale per la Ricerca sul
Cancro, Genova, Italy.
Human peripheral blood mononuclear cells (PBMC) were stimulated in vitro
with anti-lymphocyte globulin (ALG), and the phenotypic and functional
properties of the blasts obtained were investigated. When stained with
monoclonal antibodies (MoAbs), all of the blasts were identified as T cells
that expressed predominantly the CD4 phenotype (70% of the cells). The
remaining blasts were CD8+. These findings demonstrate that ALG stimulates
both helper-inducer and cytotoxic- suppressor cells at random since the CD4
to CD8 ratio in the stimulated blasts was the same as in resting PBMC. This
ratio is different from that observed in short-term cultures of T cells
stimulated with phytohemagglutinin (PHA) under the same conditions (CD4 to
CD8 ratio less than 1). ALG-stimulated T cells were cloned by limiting
dilution in the presence of recombinant Interleukin-2 (rIL-2). The clones
obtained were expanded and maintained in long term cultures with rIL-2.
Thirty-two clones were tested for their capacity of producing colony
stimulating activity (CSA) or burst promoting activity (BPA). Twenty- eight
of them produced CSA and 12 produced BPA. No correlation was found between
the surface phenotype and the ability of the clones to produce CSA or BPA
(ie, both the CD4+ and CD8+ clones released the cytokines). When 16 of the
same clones were tested for II-2 and gamma interferon (gamma IFN)
production, 12 were found to be gamma INF and IL- 2 producers. All of the
gamma IFN producers also released IL-2, whereas in the single clones no
correlation was found with the capacity of releasing BPA and CSA.
Supernatants from selected T-cell clones were also tested for hematopoietic
growth factor activities in the presence of neutralizing antisera to human
granulocyte-macrophage colony stimulating factor (GM-CSF) or to
Interleukin-3 (IL-3). It was found that most CSA was attributable to
GM-CSF, whereas BPA was mainly related to the presence of IL-3.
Volume 72,
Issue 3,
pp. 956-963,
09/01/1988
Copyright © 1988 by The American Society of Hematology
