Temporal association of CD40 antigen expression with discrete stages of human B-cell ontogeny and the efficacy of anti-CD40 immunotoxins against clonogenic B-lineage acute lymphoblastic leukemia as well as B- lineage non-Hodgkin's lymphoma cells

Abstract

Detailed immunophenotypic analyses of immunologically classified leukemias and lymphomas showed that CD40 displays an exquisite B- lineage specificity within the human lymphopoietic system. Notably, 82% of B-lineage chronic lymphocytic leukemias (CLLs), 82% of B-lineage hairy cell leukemias (HCLs), 86% of B-lineage non-Hodgkin's lymphomas (NHLs), and 29% of B-lineage acute lymphoblastic leukemias (ALLs) were CD40+. Quantitative analyses of the correlated expression of CD40 and other B-lineage differentiation antigens on fetal lymphoid precursor cells by multiparameter two-color/three-color flow cytometry, combined with analyses of sequential antigen expression on fluorescence- activated cell fluorescence activated cell sorter (FACS) isolated immunologically distinct fetal B-cell precursor subpopulations during in vitro proliferation and differentiation, provided evidence that the acquisition of CD40 antigen in human B-cell ontogeny occurs subsequent to the expression of CD10 and CD19 antigens but before the surface expression of CD20, CD21, CD22, CD24, and surface immunoglobulin M (sIgM). Some leukemic pro-B cells from ALL patients as well as normal pro-B cell clones from fetal livers displaying germline Ig heavy chain genes were CD40+, indicating that the acquisition of CD40 antigen likely precedes the rearrangement of Ig heavy chain genes. CD40+ FACS- sorted malignant cells from B-lineage ALL as well as B-lineage NHL patients were capable of in vitro clonogenic growth, indicating the CD40 antigen is expressed on clonogenic leukemia and lymphoma cells. This hypothesis was confirmed by the ability of an anti-CD40 immunotoxin that we used as an antigen-specific cytotoxic probe to effectively kill clonogenic B-lineage ALL and NHL cells.

Role of the CD40 and CD95 (APO‐1/Fas) antigens in the apoptosis of human B‐cell malignancies

“…Expression and function of CD40 and CD95 on unstimulated neoplastic B cells CD40 antigen was expressed on the surface of all 30 B-cell neoplasms tested (Table I). As previously described (Uckun et al, 1990), ALL cells tended to express a lower level of CD40 compared to CLL and NHL cells. In contrast to CD40, CD95 was not readily detectable on most samples of B-cell malignancies.…”

“…Ligation of CD40 induces the proliferation of resting B cells and inhibits the apoptosis of activated B cells. The CD40 antigen is expressed early in B-cell ontogeny and may also participate in the activation and proliferation of immature B-cell precursors (Saeland et al, 1993;Uckun et al, 1990Uckun et al, , 1991.…”

The humanized CD40 antibody SGN‐40 demonstrates pre‐clinical activity that is enhanced by lenalidomide in chronic lymphocytic leukaemia

“…Further, we have also showed lenalidomide to mediate NK cell activation and subsequent enhanced ADCC function against target CLL B cells using clinically relevant therapeutic antibodies . Given the well defined expression of CD40 antigen on CLL B cells (Uckun et al, 1990) and its ability to serve as a potential target for antibody therapy in large cell lymphoma and multiple myeloma cell lines (Tai et al, 2004(Tai et al, , 2005Law et al, 2005), this study examined the preclinical activity of SGN-40 and its combination with lenalidomide in primary B cells from CLL patients. Modest apoptosis and ADCC mediated by SGN-40 in CLL B cells was found to be significantly enhanced by lenalidomide, an agent that upregulates CD40 antigen in CLL B cells.…”

Acquisition of CD40 Expression During Murine B‐Cell Differentiation

“…In human B-cell development, the issue is yet not completely clear concerning levels of CD40 expression among B-cell precursors. In some reports it is claimed that CD40 can be detected as early as among pro-B cells as well as on pre-B cells [11][12][13], whereas another report shows that CD40 expression on late pre-B cell is rather low but can be up-regulated upon interaction with activated Th cells and IL-4 [35]. Furthermore, long-term in vitro growth of human B-cell precursors expressing CD40 has recently been reported [36].…”

“…In humans, CD40 expression was demonstrated on a multitude of both transformed and non-transformed cell types including mature B cells [10], pro-and pre-B cells [11][12][13], follicular dendritic cells [14], thymic epithelial cells [15] and carcinomas of various origin [16]. In this report we analysed the expression of CD40 by murine cell lines propagated in vitro, as well as by freshly isolated murine lymphocytes, using both a soluble recombinant CD40-ligand fusion protein [17], as well as a MoAb directed against CD40.…”