Monoclonal B‐cell lymphocytosis in blood donors

Abstract

Summary Monoclonal B‐cell populations have been detected in the peripheral blood of apparently healthy individuals by flow cytometry. In 2005, the term monoclonal B‐cell lymphocytosis (MBL) was proposed to describe these findings. MBL may be immunophenotypically similar to chronic lymphocytic leukaemia (CLL) and, like CLL, the prevalence is higher in males and older individuals. We studied the prevalence of MBL in blood donors from the Midwestern United States. Samples from 5141 donors were examined and seven (0·14%) were found to have immunophenotypic characteristics of MBL or CLL. Immunoglobulin heavy chain analysis yielded monoclonality or oligoclonality. Prior and subsequent to the study, an additional undetermined number of blood donors were screened and seven of these expressed immunophenotypic characteristics of MBL or CLL. We thus found a total of 14 healthy blood donors with monoclonal expansions of B‐lymphocyte populations. Of these, 12 were presumptively classified as MBL and two as CLL. All but two of the donors were male; the mean age was 59 years. The clinical importance of these findings with regard to transfusion medicine has not been established.

Long‐term follow‐up of monoclonal B‐cell lymphocytosis detected in environmental health studies

“…Monoclonal B-cell lymphocytosis (MBL) became a welldefined hematologic condition (5) on the basis of findings in familial CLL (7), communities near hazardous waste sites (1-4), and other populations (8)(9)(10)(11)(12)(13)(14)(15)(16). This report extends our previous observations of MBL detected during environmental health studies conducted from 1991 to 1994 and in subsequent medical follow-up evaluations conducted in 1997, 2003, and 2009.…”

“…Combining these four surviving cases with the four deceased cases previously reported (4), gives seven kappa and one lambda, a possible bias toward kappa that has been observed in some (6,15), but not all studies of MBL (16).…”

The immunoglobulin gene repertoire of low-count chronic lymphocytic leukemia (CLL)–like monoclonal B lymphocytosis is different from CLL: diagnostic implications for clinical monitoring

“…The existence of monoclonal B lymphocytes in the blood of otherwise healthy individuals has long been known, [1][2][3][4] but only recently has the frequency of this phenomenon been fully appreciated, thanks to more advanced flow cytometry techniques. 5,6 Monoclonal B-cell expansions, now named monoclonal B lymphocytosis (MBL), 7 are rather heterogeneous in terms of phenotype.…”

Early-Stage Gastric MALT Lymphoma: Is It a Truly Localized Disease?

“…Using the same methodology, an IgH rearrangement of the same size was detected in the blood of 28 of 62 (45%) patients. Because the detection of a monoclonal product in the blood per se cannot definitely prove clonal identity between blood and stomach [35], we further compared the sequences of the two compartments. Sequencing was performed in five randomly picked stage I patients with available blood and gastric tissue.…”