Significance of Cross Lineage Antigen Expression in Acute Lymphoblastic Leukemia

Background: Aberrant expression of cross-lineage antigens gives valuable insight into the diagnosis and prognosis of acute leukaemia. In countries like India, cytogenetic tests are widely accessible. Exploring the prognostic value of an accessible test is of great importance. Therefore, establishing a population-specific immunophenotype database will enable to design an antibody panel equipped to detect cross-lineage antigen expression. The aim of this study was to determine the frequencies of cross-lineage antigen expression in Acute Lymphoblastic Leukaemia (ALL), its relationship with clinical features, and changes in blood counts during the treatment course. Methods: This was a retrospective observational study conducted at a tertiary care hospital. Consecutive ALL cases over 2 years were reviewed. Relation of cross-lineage aberrant antigens with blood counts and clinical features were studied. Chi-square test and Fisher’s exact test were used. Results: A total of 149 ALL cases were included in the study. Thirty (20.1%) cases showed expression of cross-lineage antigens. CD7 was the most commonly expressed cross-lineage antigen, seen in 14 (10.5%) cases of B-ALL. CD13, seen in eight (5.3%) patients, was the most frequent aberrant myeloid antigen. Myeloid aberrancies were associated with lower WBC count and blast count while aberrancies of T-cell antigens on B-ALL showed higher WBC count and blast count. Conclusions: Cross lineage antigenic aberrancies influence blast count and WBC count. Documentation of these aberrancies in ALL helps in prognostication and monitoring of the disease.