Raymond E. Felgar

Activated human B lymphocytes express cyclooxygenase-2 and cyclooxygenase inhibitors attenuate antibody production.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used for the treatment of inflammatory diseases and target cyclooxygenases 1 and 2 (Cox-1, Cox-2) that are responsible for PG production. Newer Cox-2-selective drugs have been heavily prescribed to quench inflammation. Little is known about whether or not these drugs influence human B lymphocytes and their ability to produce Ab. We report herein that activated human B cells not only highly express Cox-2 and produce PGs, but that the NSAID indomethacin and Cox-2-selective drugs profoundly inhibit the ability of human B cells to produce IgG and IgM in vitro. Human blood B cells highly express Cox-2 mRNA and protein and produce PGs after activation with CD40L, pansorbin, or CD40L plus BCR engagement. Cox-2 is also highly expressed by human tonsil B cells, as shown by immunohistochemistry. Cox-inhibiting drugs modestly affect purified B cell proliferation but profoundly reduce Ab production. The ability of whole blood to produce IgM and IgG following stimulation is also strongly inhibited. In support that Cox-2 plays a seminal role in B lymphocyte Ab production, Cox-2 knockout mice have 64% less IgM and 35% less IgG than normal littermate controls. These findings support that NSAIDs and the new Cox-2-selective drugs have an unsuspected target, the B cell, and attenuate Ab production in humans. Use of NSAIDs may therefore influence autoantibody production in autoimmune diseases and may dampen humoral immunity in response to antigenic challenge/vaccination.

The expression of TIA-1+ cytolytic-type granules and other cytolytic lymphocyte-associated markers in CD30+ anaplastic large cell lymphomas (ALCL): correlation with morphology, immunophenotype, ultrastructure, and clinical features.

Anaplastic large cell lymphomas (ALCL) are a heterogeneous group of CD30+ large cell lymphomas; the most characteristic type have a T or null cell phenotype, often express epithelial membrane antigen (EMA) and cytolytic lymphocyte markers, and often possess a nonrandom t(2;5)(p23;q35) chromosomal translocation. We studied 22 (19 T, 1 null, 2 B cell) ALCL, including four primary cutaneous ALCL (PC-ALCL), for the expression of TIA-1, the cytotoxic T lymphocyte (CTL) or natural killer (NK) cell-associated antigens CD4, CD8, betaF1, TCRdelta1, CD56, and CD57, the ALCL-associated antigens p80 and EMA, and the Hodgkins disease-associated marker CD15 to better define the relationship of these markers to histological subtype, primary site, and patient clinical characteristics. TIA-1 expression was seen in 12 of 20 (60%) T or null cell ALCLs with a cytoplasmic, granular distribution. Ultrastructural studies showed cytotoxic-type granules (dense core, multivesicular, and intermediate types) with TIA-1 localized to granules on immunogold labeling. TIA-1 staining strongly correlated with young patient age (< or = 32 years, P < .05) and EMA expression (P < .05). Excluding the four PC-ALCL cases, TIA-1 staining also correlated with p80 expression (P < .05) in all of the T cell cases. Three CD15+ cases were TIA-1-. TIA-1 expression in T or null cell ALCL was seen in all morphological subtypes (2 of 2 small cell variant, 3 of 4 monomorphic variant, and 7 of 14 pleomorphic variant) and primary tumor sites (6 of 14 nodal, 2 of 4 primary cutaneous, 2 of 2 bone, and 2 of 2 soft tissue). TIA-1+ granules were seen in all subsets: 5 of 6 CD4+, 1 of 2 CD8+, 4 of 8 CD56+, and 1 of 2 CD57+ ALCL. Of note, 4 of 10 T or null cell ALCL expressed gammadelta T-cell receptors (TCR), whereas only 1 of 10 T or null cell ALCL was alphabeta TCR+; TCR were not detected in five cases. TIA-1 was expressed by 3 of 4 gammadelta TCR+ ALCL and 1 of 1 alphabeta TCR+ ALCL. These data support a cytotoxic lymphocyte phenotype in most T or null cell ALCL and suggest that some T cell ALCL are derived from cytolytic CD4+ T cells, gammadelta T cells, or NK-like (CD56+ or CD57+) T cells.

Burkitt’s leukemia with precursor B-cell immunophenotype and atypical morphology (atypical Burkitt’s leukemia/lymphoma): case report and review of literature

A 45-year-old male presented with fever, night sweats, splenomegaly, high LDH, high uric acid, and high blast count with atypical L3 morphology. Flow cytometry showed neoplastic clone consistent with pre B-cell immunophenotype, on the basis of lack of cytoplasmic immunoglobulins, surface immunoglobulins, and light chain immunoglobulins. Cytogenetic analysis revealed t(8;14)(q24; q32), the characteristic translocation of Burkitts leukemia. A few similar case reports of Burkitts leukemia with precursor B-cell immunophenotype have been described primarily in pediatric literature and usually with typical L3 morphology. This case recognizes this subset in adult ALL and emphasizes the need for comprehensive diagnostic analysis.

Early gene activation in chronic leukemic B lymphocytes induced toward a plasma cell phenotype.

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of lymphocytes that are arrested at an intermediate stage of B lymphocyte development. CLL B lymphocytes transform (mature) to a plasmacytic phenotype with loss of CD19 and CD20 and the appearance of cytoplasmic immunoglobulin when treated in vitro with phorbol esters. We have used array hybridization technology to describe gene expression patterns for untreated and tetradecanoyl phorbol acetate (TPA)-treated CLL B cells at 5, 10, and 20 min following initial TPA exposure. Three genes, early growth response factor 1 (EGR-1), dual specificity phosphatase 2, and CD69 (early T-cell activation antigen), showed a 2.0-fold or greater increase in mRNA transcription at four or more of six time points in two studies. Upregulation of expression of these genes was confirmed by real-time polymerase chain reaction in the TPA-treated cells of four CLL patients. A progressive increase in gene expression was observed during the 20-min time course for all three genes. In addition, protein expression of EGR-1 and CD69 was increased as measured by immunofluorescence cell analysis. Several genes (PKC, n-myc, jun D, and BCL-2) previously reported as overexpressed in CLL lymphocytes were overexpressed in these studies also, but were not altered by TPA treatment. Genes for proteins whose upregulation requires hours of TPA exposure (the 4F2hc component of the L-system amino acid transporter, prohibition, and hsp60) were assessed, and their later expression contrasted with the early expression of EGR-1, dual specificity phosphatase 2, and CD69. EGR-1 encodes a zinc-finger transcription factor that is induced by pokeweed mitogen and TPA and promotes B lymphocyte maturation. The dual specificity phosphatase 2 encodes an enzyme that reverses mitogen activated protein kinase cell activation by dephosphorylation. The CD69 protein is induced by TPA in thymocytes and is a type II transmembrane signaling molecule in hematopoietic cells. These findings suggest that the products of these three genes may be central to early steps in the TPA-induced evolution of CLL B cells to a plasmacytic phenotype.

Minimal residual disease detection by flow cytometry: can it serve as a predictor of future relapse?

Commentary on Flow cytometric analysis of aberrant antigen expression of blasts using CD45 blast gating for minimal residual disease in acute leukemia and high-risk myelodysplastic syndrome by Shigeki Ito, Yoji Ishida, Kazunori Murai, Shin-ichiro Kuriya.