Membrane and soluble apo-1 as a marker of apoptosis in patients with acute leukemia

Abstract EN

Purpose : we have planned this work to evaluate the significance and prognostic values of both membrane and soluble APO-1 as markers of apoptosis in patients with acute leukemia before and after chemotherapy.

Methods and Materials: For that, 30 patients suffering from acute leukemia (15 patients with ALL and 15 patients with AML) and 10 apparently healthy individuals serving as control group, were selected and subjected to the following: thorough history and clinical examination, routine investigations including: complete blood picture, bone marrow examination, cytochemistry, immunopheno-typing of the blast cells and specific investigations including: detection of mAPO-1 (CD95) on surface of blast cells by flow cytometry, detection of DNA fragmentation by ag-arose gel electrophoresis and measurement of soluble APO-1 by ELISA technique before and after chemotherapy.

Results : surface membrane CD95 was found to be expressed on the majority of ALL blast cells (86.6 %) and in only 60 % of AML blast cells.

The degree of surface membrane expression was variable ranging from 23-86 % in ALL and from 43-89 % in AML.

In both ALL and AML patients, a significant relationship was detected between surface CD95 expression and response to initial induction chemotherapy.

Ninety-one percent of ALL patients and 84 % of AML patients who had surface CD95 expression > 20 % on their blast cells showed complete hematological remission after initial induction chemotherapy.

This was confirmed by finding that DNA extracted from patients under chemotherapy, whose blast cells CD95 expression was > 20 %, showed DNA fragmentation (DNA laddering) by agarose gel electrophoresis (characteristic of apoptosis).

As regards soluble CD95 (SCD95) before starting chemotherapy, no statistically significant difference was observed between the level of soluble CD95 in both ALL and AML patients and the control group (p > 0.05).

But, in AML patients, the level of soluble CD95 tended to be elevated (not significantly) in comparison with normal control.

After initial induction chemotherapy, the level of soluble CD95 was found to be significantly decreased in both ALL and AML patients in comparison to its level before therapy (p < 0.001 and < 0.01, respectively).

By following up patients who were resistant to chemotherapy, it was observed that patients who did not achieve complete remission after induction chemotherapy had relatively higher levels of sAPO-1.

Conclusion : from these results we can conclude that, since there is a significant relationship between surface CD95 expression in both ALL and AML patients and response to chemotherapy, the expression of surface CD95 could serve as a new prognostic marker as it is helpful in predicting the outcome of therapy.

In addition, because soluble APO-1 was found to be relatively high in patients resistant to anti-leukemic therapy, so measurement of s-APO-1 in sera of acute leukemia patients could serve as a putative marker for an active persisting leukemia.