M. Klobusicka et O. Babusikova, IMMUNOPHENOTYPIC CHARACTERISTICS OF T-ACUTE LYMPHOBLASTIC-LEUKEMIA CELLS IN RELATION TO DPP IV ENZYME EXPRESSION, Neoplasma, 45(4), 1998, pp. 237-242
In the present study we have examined immunophenotypic characteristics
of T-acute lymphoblastic leukemia (T-ALL) cells in relation to the ex
pression of enzyme dipeptidyl peptidase IV (DPP IV). Peripheral blood
and bone marrow cells of TALL patients at diagnosis were estimated. Ce
ll surface markers were detected by a standard immunofluorescence assa
y and FACStar flow cytometry using a broad panel of monoclonal antibod
ies to define T-cell immunophenotype. DPP IV activity was investigated
in phenotypically defined T-lymphoblasts. Association between DPP IV
expression and proliferation was monitored by the expression of CD71 a
nd CD38, which could be considered as markers of activation and prolif
eration, and by the silver-staining of nucleolar organizer regions-rel
ated proteins (argyrophilic proteins). Lymphoblasts, divided according
to the presence or absence of DPP IV activity revealed remarkable het
erogeneity in the immunophenotypic features. The vast majority of DPP
IV positive TALL cases expressed CD4, CD8, CD7, CD5, CD2 along with CD
71 and CD38 antigens, but the cells were surface membrane CD3 antigen
negative. The phenotype of DPP IV negative cases displayed membrane CD
3 antigen and variable expression of CD4 and CD8. CD71 and CD38 were f
requently negative, It appears, that DPP IV active cells form the popu
lation with immature phenotype, as evidenced by mCD3 antigen absence.
Relation between DPP TV positive cells and proliferation activity of T
-blasts was observed, given by the presence of CD71 and CD38 positivit
y and overexpression of argyrophilic proteins (AgNORs). In conclusion,
our study indicates a close relationship between DPP IV activity and
the features of T-cell immaturity. Association among DPP IV, CD71, CD3
8 and AgNORs might reflect possible relationship between immature phen
otype and proliferative ability of blast cells in T-ALL patients.