[Human acute leukemia. II. Acute lymphoblastic leukemia. Complex classification of acute leukemia].

Acute lymphoblastic leukaemias originate from cells committed either to T-lineage (T-ALL) or B-lineage (nonT-ALL). Leukaemic cells are classified into these lines according to the expression of lineage specific differentiation markers, which are T-cell receptors, associated with CD3 antigenic complex, for the T-line and immunoglobulins for the B-line. T-ALL seem to be one type of disease, in the B-lineage it is possible to distinguish several types of diseases according to clinical findings and immunoglobulin expression. Monoclonal antibodies directed against various surface antigens are used for diagnosis of ALL and their significance in various types of ALL is evaluated. Specificity of diagnostic markers is discussed especially from the point of the so called "mixed acute leukaemias", cells of which should differentiate in myeloid and lymphoid lines. The existence of a single one "mixed acute leukaemia" has not yet been reliably proved with the use of lineage specific differentiation markers. Present knowledge of karyotype findings in acute leukaemias classified according to specific differentiation markers is reviewed and the necessity to introduce a complex classification on this basis is stressed.