Common ALL associated antigen from cell surface and serum: molecular properties and clinical relevance.

Detection of distinct cell surface markers has brought up remarkable improvements not only in diagnosis and classification of leukemic diseases, but also has gained immediate clinical relevance concerning therapeutic aspects. Especially. such markers may give information about the antigenic phenotype reflecting the origin of distinct leukemic cells from different stem cell compartments and their degree of maturation. Recently a cell surface antigen has been detected, which so far seems to be highly specific for common ALL (cALL) cells. Interestingly, in some cases this antigen has also been found on T-ALL cells and on cells appearing in blastic crises of CML [7] . Nevertheless, the detection of this common ALL associated antigen (Ag cALL) has been proved to be useful in clinical practice especially in combination with other routinely applied tests for cell surface markers, e.g. E-rosetting, immunoglobulines and C-receptors. We here describe the solubilization and partial physico-chemical characterization of the cALL associated surface antigen. Furthermore, a glycoprotein exhibiting the cALL antigenic specificity could be isolated from the Sera of two patients in active relapses of common ALL. .