The Relationship between the Immunophenotypic Profile and Cytogenetic Abnormalities in Acute Myeloid Leukemia.
Authors: Lunghi Monia , Vanelli Laura , Bernasconi Paolo , Boni Marina , Portolan Monica , Pascutto Cristiana , Algarotti Alessandra , Griva Vassiliky , Castagnola Carlo , Lazzarino Mario 
Published: October 2019

Abstract
We studied the immunophenotypic characteristics of 459 consecutive adult AML patients and their correlation with karyotype. Immunophenotype was performed using a panel of 26 directly conjugated monoclonal antibodies. Cytogenetic analysis was performed using a standard G-banding technique. Karyotype was available in 394 patients (not done in 15, failed in 50): 1) 45 (11.4%) were t(15;17) APL patients with a mature myeloid phenotype (HLA-DR-/CD13+ and/or CD33+). CD2 and CD56 were expressed in 20% and 13.3% of cases, respectively. CD11b-positivity was less frequent than in the other cytogenetic groups. The markers significantly associated with t(15;17) were: presence of CD2 (two tailed Fisher exact test: p=.003) and CD117 (p=.01), absence of CD4dim (p<.001), CD7 (p<.001), CD11b (p<.001), CD11c (p<.001), CD14 (p<.001), CD34 (p<.001), TdT (p=.03) and HLA-DR (p<.001). 2) 12 (3%) showed t(8;21) and were characterized by CD34+/CD19+/CD13+<CD33+ in more than 80% of blasts. CD56 were expressed in 87.5%. CD11b was positive only in 8.3% and CD14 was constantly negative. In univariate analysis, t(8;21) was associated with CD11b- (p=.03), CD19+ (p<.001) and CD56+(p<.001). 3) 23 (5.8%) had inv(16) or t(16;16) with CD13+/CD33+ in >90% of blasts, CD34+ in 70%, MPO+ in 95.8% and HLA-DR+ in 89.3%. The association with CD14 and TdT was of borderline statistical significance. 4) 24 (6.1%) had −5/5q- with more than 80% of blasts CD117+/CD13+>CD33+. CD34 was positive in 62.9% of cases, CD7 in 33%, CD11b in 35.7%, CD11c in 67.8% and CD14 in 7.1%. CD15-positivity was less frequent than in other AML subtypes. Univariate analysis showed a trend of positive association with CD7 and CD117. 5) 40 (10.2%) showed −7/7q-, with CD13+>CD33+ detected in more than 80%, CD7 in 33.3%, CD11b in 72.7%, CD15 in 55%, CD34 in 73.3%. Abnormal CD16/CD33 and/or CD11b/CD66b myeloid cell pattern was detected in 40% of cases (p=.001). −7/7q- were significantly associated with CD34 (p=.02) and CD7 (p=.04). 6) 41 (10.4%), had complex karyotype (≥3 abn) with a similar antigenic profile than group 4) and 5) but with a more frequent expression of CD11b, CD14, CD15 and less frequent of MPO. In univariate analysis CD19 (p=.04), CD34 (p=.02) and MPO (p<.001) retained statistical significance. 7) 20 (5.1%) with +8 were CD13+ in 95.6%, while the other markers were present in less than 80% of cases, in particular lower CD33+ blasts (p=.01). 8) 17 (4.3%) had 11q23abn, with CD13+<CD33+, frequent TdT+ (61.5%) and rare CD34+ (31.8%, p=.02). CD11c and CD14 were more frequently expressed than in other subtypes (86.4% and 36.4%, respectively). T-lymphoid markers were present in 36.4%. Univariate analysis showed a positive association between 11q23abn and presence of CD11c (p=.04) and CD14 (p=.05). 9) 115 (29.2%) with a normal karyotype had a dishomogeneous antigenic profile. CD2 (p=.002), CD11c (p=.04) and HLA-DR (p<.001) were the most discriminant markers. Using a multivariate discriminant analysis, we identified a discriminant function only for group 1) and group 2), based on CD11c/CD13/CD34/MPO/HLA-DR (sensitivity >99%, specificity 94.7%) and CD7/CD11c/CD19/CD56/MPO/HLA-DR (sensitivity 83.3%, specificity 94.5%), respectively. We conclude that in AML patients some cytogenetic abnormalities are associated with peculiar antigenic profiles. In patients with normal karyotype the heterogeneity of antigenic pattern may reflect underlined distinct molecular abnormalities.