This discussion focuses on diagnostic pitfalls related to the use of immunohistochemistry for CD20 and CD3 in hematopathology, and specifically on diagnostic challenges that arise when (1) CD20 is not expressed in B-cell lymphomas, when (2) CD20 is expressed in plasma cell neoplasms and T-cell lymphomas, and when (3) CD3 is expressed in B-cell lymphomas and Hodgkin lymphoma.
Quantitative polymerase chain reaction (PCR) with patient-specific, allele-specific oligonucleotide (ASO) primers for individual immunoglobulin H VDJ region (ASO-PCR) amplification was performed using several sources of clinical material, including mRNA from peripheral blood cells (PBMNCs), whole bone marrow cells (BMMNCs), and the CD20+ CD38- B-cell population in bone marrow, as well as cell-free DNA from the sera of patients with multiple myeloma (MM).
Next, using the NK-92 (mCD16) we compared mouse mAbs directed at B lineage specific CD antigens for their ability to induce ADCC against human Epstein-Barr virus- infected B lymphoblastoid (for anti-CD19, -CD20 and -CD21) or against myeloma (for anti-CD38 and -CD138) target cells.
The t(11;14) MM group was associated with a significantly higher positive rate of B-lineage associated antigens CD20 and CD79a as well as the lack of CD56 expression. t(11;14) was less likely to be accompanied by 13q14 deletion than 13q14 deletion frequency in non-t(11;14) population (p=0.026), and fewer patients displaying t(11;14) were identified as belonging to the high-risk cytogenetic group due to the extremely low incidence of t(4;14) and t(14;16).
Plasma cell myelomas with t(11;14)(q13;q32) were frequently CD20(+) (46.4%) and CD56(-) (53.8%) and had a nonhyperdiploid karyotype (97.6%) with frequent 13q deletion (33.3%).Of 42 cases, 19 (45.2%) expressed CD23.
Despite more rapid onset and higher rate of CR than in other molecular subgroups, CRD was inferior in CCND1 without CD20myeloma, resembling outcomes in MAF/MAFB and proliferation entities.
Bone marrow aspiration biopsy exhibited plasma cell myeloma, in which atypical plasma cells were positive for cytoplasmic IgA (kappa) and atypical lymphoid cells intermingled were positive for CD20.
In view of these findings, the anti-CD20 chimeric monoclonal antibody, rituximab (Rituxan; Genentech, Inc, South San Francisco, CA and IDEC Pharmaceutical Corporation, San Diego, CA), has been evaluated in the treatment of Waldenstrom's macroglobulinemia and multiple myeloma, as well as in nonmalignant plasma cell disorders including IgM polyneuropathies, immune thrombocytopenias, and autoimmune hemolytic anemias, with reported activity in these entities.
Immunophenotypic expression was similar for CD38, CD138, CD2, CD3, CD16, CD10, CD13, and CD15, but PCL differed from MM in the expression of CD56, CD9 HLA-DR, CD117, and CD20 antigens.
Serial blood and marrow specimens from eight adult recipients of sex-mismatched transplants (BMT) for chronic myeloid leukemia (CML, n = 3), Ewing sarcoma (n = 1), acute myeloid leukemia (AML) in second remission (n = 1), acute lymphatic leukemia (ALL, n = 1) and multiple myeloma (n = 2) were analyzed by the simultaneous immunophenotypic CD3, CD4, CD8, CD20, CD34, CD10 and genotypic analysis (for X and Y chromosomes).
The peripheral blood lymphocytes from 42 patients with multiple myeloma (MM) and 13 patients with monoclonal gammopathy of undetermined significance (MGUS) were studied by three-color immunofluorescence (IF) using antibodies directed to a broad range of B-cell markers (CD19, CD20, CD21, CD24), CALLA (CD10), PCA-1 (a plasma cell marker), and to the high and low molecular weight isoforms of the leukocyte common antigen, CD45RA (p205/220) and CD45RO (p 180).