The association of an IgM-Fc receptor (FcR) with chronic lymphocytic leukemia (CLL) was suggested more than 30 years ago, but its authenticity has never been formally addressed. We exam IntroductionChronic lymphocytic leukemia (CLL) is the most common leukemia of adults in Western countries and accounts for ϳ 30% of all cases of leukemia in the United States. It is a heterogeneous leukemia that is thought to originate from antigen-stimulated B cells that escape from normal cell death mechanisms. 1,2 Survival of CLL patients ranges from a few years to several decades. The most reliable marker thus far for predicting the prognosis of CLL is the mutation status in the immunoglobulin heavy chain variable region (IGHV). Unmutated (UM)-CLL is aggressive and mutated (MT)-CLL is more indolent. [3][4][5] Because DNA sequencing is not practical for most clinical laboratories, various cell surface and intracellular proteins have been explored as potential surrogate markers. ZAP-70, a Syk family tyrosine kinase normally expressed in T cells, has proved to be a very good indicator for UM-CLL, but the required intracellular staining is technically challenging and results in diagnostic inconsistency among clinical laboratories. [6][7][8][9][10][11] Other markers, including membrane proteins (eg, CD38, Fc receptor-like protein 2) and serum proteins (eg, thymidine kinase, soluble CD23, and ␤2-microglobulin), also have been studied as surrogate prognostic indicators. 3,4,[12][13][14][15][16][17] The association of the IgM Fc receptor (FcR) with CLL has long been suggested based on the ability of CLL cells to form rosettes with IgM-coated erythrocytes. [18][19][20][21][22] Unfortunately, this early intriguing suggestion was not pursued thereafter, probably because of uncertainties with such a crude detection procedure. During the course of analysis of B-cell activation antigens with the BAC-1 mouse IgM monoclonal antibody (mAb), we serendipitously found an IgM-binding protein of ϳ 60 kDa that was expressed on CLL B cells and activated normal B cells by immunofluorescence and biochemical analyses using various IgM ligands. 23,24 The gene encoding an authentic FcR has defied identification until our recent discovery of a bona fide FcR cDNA in the B-lineage libraries, including one library derived from CLL B cells. 25 Surprisingly, the corresponding FCMR gene had been already reported as TOSO or Fas apoptosis inhibitory molecule 3 (FAIM3). 26 Notably, the reported inhibition of apoptosis was based on an assay in which apoptosis was induced by ligation of Fas on the Jurkat T-cell line with a mouse IgM mAb (CH11). Our results indicated that FcR per se had no inhibitory activity in Fas-mediated apoptosis and that such inhibition was only achieved when anti-Fas mAb of an IgM but not IgG isotype was used for inducing apoptosis. 25 This incorrect designation has led to the misconception that enhanced FAIM3/TOSO expression by CLL cells may be linked to their resistance to cell death mechanisms. [27][28][29] Here, we examined the expression...

DNA-membrane association critical for initiation of DNA replication in Bacillus subtilis can be classified into two types. Type I is salt resistant and dependent on the initiation gene, dnaB, and type II is salt sensitive and independent of the dnaB gene. We found and sequenced two adjacent areas of type II binding within 1% of oriC on the B. subtiis chromosome.

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