Stages of T-Cell Receptor Protein Expression in T-Cell Acute Lymphoblastic Leukemia

Abstract

AbstractIn this study five monoclonal antibodies (MoAbs) to T-cell receptor (TCR) proteins (WT31, άF1, βF1, TCRδ-1 and δTCS-1) were used to identify discrete maturative stages in 40 cases of T-cell acute lymphoblastic leukemia (T-ALL). These MoAbs reacted exclusively with CD3+ T cells and did not label B-lineage and myeloid cells. In 17 of the 40 T-ALL cases studied the leukemic blasts lacked membrane and cytoplasmic TCR chains (group I). In 12 cases cells did not have membrane CD3/TCR but expressed cytoplasmic TCR proteins heterogeneously: nine cases had cytoplasmic TCRβ chains (βF1+ άF1−-; group II), one case had cytoplasmic TCRά chains (άF1+, βF1−; group III), and two cases were labeled by both άF1 and βF1 MoAbs (group IV). The remaining 11 cases were mCD3+: nine were TCRάβ+ (group Va) and two exhibited TCRγδ (TCRS-1+, δTCS-1+; group Vb). The analysis of the TCRβ, -γ, and -δ gene configurations in 23 of the 40 T-ALLs showed that: (1) the lack of TCR protein expression was due to the lack of TCR gene rearrangements only in one of nine cases; (2) five of five TCRβ+, TCRά− cases studied had germline TCRa genes (ie, no detectable TCRδ gene deletions); (3) seven of eight cases with TCRδ gene deletions expressed TCRά proteins, whereas in 12 of 20 of the T-ALLs with TCRβ gene rearrangements the synthesis of the corresponding protein occurred; only 2 of 16 cases with rearranged TCRδ genes expressed TCRS chains. The T-ALL categories identified with anti-TCR MoAbs did not have additional characteristic phenotypic patterns and may correspond to the normal stages of T-cell development more precisely than those defined by other differentiation antigens.