Factors determining whether diffuse large B-cell lymphoma samples are detected by flow cytometry.

INTRODUCTION: Flow cytometry (FCM) is widely used in the diagnosis of mature B-cell neoplasms (MBN), and FCM data are usually consistent with morphological findings. However, diffuse large B-cell lymphoma (DLBCL), a common MBN, is sometimes not detected by FCM. This study aimed to explore factors that increase the likelihood of failure to detect DLBCL by FCM. METHODS: Cases with a final diagnosis of DLBCL that were analysed by eight-colour FCM were retrospectively collated. Clinical, FCM, histopathological and genetic data were compared between cases detected and cases not detected by FCM. RESULTS: DLBCL cases from 135 different patients were analysed, of which 22 (16%) were not detected by FCM. In samples not detected by flow cytometry, lymphocytes were a lower percentage of total events (p = 0.02), and T cells were a higher percentage of total lymphocytes (p = 0.01). Cases with high MYC protein expression on immunohistochemistry were less likely to be missed by FCM (p = 0.011). Detection of DLBCL was not different between germinal centre B-cell (GCB) and non-GCB subtypes, not significantly affected by the presence of necrosis or fibrosis, and not significantly different between biopsy specimens compared to fine-needle aspirates, or between samples from nodal compared to extranodal tissue. CONCLUSION: The study identifies several factors which affect the likelihood of DLBCL being missed by FCM. Even with eight-colour analysis, FCM fails to detect numerous cases of DLBCL.

Generation of murine monoclonal antibodies to Haemophilus influenzae type b capsular polysaccharide by in vivo immunization.

Haemophilus influenzae type b (Hib) is a pathogenic gram-negative bacterium associated with human disease, especially in young children. Protective immune response to Hib results from antibodies developed against the polyribosylribitol phosphate (PRP) capsular polysaccharide of the bacterium. Several investigators in the study of immune response to Hib have produced human monoclonal antibodies to PRP. Only two previous groups have reported the generation of murine anti-PRP monoclonal antibodies using either immunizing mice with inactivated Hib bacteria or a combination of in vivo and in vitro immunization of mice with PRP conjugate antigen (PRP-D). In this present study, we generated murine anti-PRP monoclonal antibody secreting hybridomas for the first time by simple in vivo immunization with PRP conjugate antigen (PRP-T). The anti-PRP antibodies from one hybridoma clone (B10) are further characterized and potential applications are discussed.

Isolation of antigen-specific B cells.

Cell separation techniques are important in immunology. Major cell populations can be separated successfully with high purity. However, isolation of cells which are specific for particular antigens is more challenging because of the relatively small numbers of antigen-specific cells, and the lack of independent markers available to determine the purity of the isolated population. In this review, the literature describing three principal techniques used to separate antigen-specific cells has been reviewed. Particular emphasis has been placed on yield and purity; the two most important parameters of any purification method. The most promising isolation methods have used immunomagnetic sorting and multiparametric flow cytometric analysis.