A monoclonal antibody for detection of folylpolyglutamate synthetase in paraffin embedded tissues.

Folate biochemical pathway enzymes such as folylpolyglutamate synthetase (FPGS) are key elements in the folate pathway. The role of FPGS is to add glutamate residues to folates and antifolates, trapping them in the cell and increasing their affinity for subsequent enzymatic reactions. FPGS may also be an indicator of response to both clinically established and novel antifolate drugs such as pemetrexed; knowledge of their level of expression in tumors may enable their optimal use by identifying potentially responsive subgroups of patients. In spite of its key role in both nucleotide biosynthesis and possible role as a determinant of response in chemotherapy, monoclonal antibodies to FPGS suitable for immunohistochemical analysis of formalin fixed and paraffin embedded biopsy samples, or that can be used for Western blot analysis, are not commercially available. The aim of this study was to generate a monoclonal antibody that could be used to detect specific expression of FPGS in paraffin embedded tissues. A 228 amino acid region of the FPGS sequence was expressed as a recombinant fusion protein and used as an antigen to generate monoclonal antibodies. ELISA and Western blot studies identified specific reactivity of the NN3.2 antibody to the recombinant protein and a single 60 kDa protein in whole cell lysates from cell lines known to express FPGS. Immunohistochemical analysis of FPGS using hybridoma clone NN3.2 in a panel of normal tissues demonstrated wide expression including strong immunoreactivity in the brush border and crypts of colon, liver hepatocytes, and lymphoid cells. Analysis of a panel of malignant and benign tissues demonstrated wide expression with variable intensities of staining and patterns of cytoplasmic reactivity. Stronger staining was observed in malignant tissue compared with that of normal adjacent tissue, particularly in ovarian and colon adenocarcinoma cases. Our results show that clone NN3.2 is a sensitive tool for detection of FPGS in paraffin-embedded tissues.

Phospho-STAT5 and phospho-Akt expression in chronic myeloproliferative neoplasms.

The majority of Myeloproliferative Neoplasms (MPNs) are characterised by mutations in genes encoding molecules or receptors involved in cell signalling, the most common being the JAK2 V617F mutation. This mutation leads to ligand-independent activation of downstream signalling pathways by constitutive phosphorylation. The signalling pathways affected include the Janus kinase-signal transducers and activators of transcription (JAK-STAT) and phosphotidylinositide-3 kinase (PI3K) pathways, which regulate cell survival and apoptosis respectively. Monoclonal antibodies to phospho-STAT5 and phospho-Akt were generated and assessed by immunocytochemistry on bone marrow biopsies of MPN patients with JAK2 V617F, JAK2 exon 12, MPL exon 10 and KIT D816V mutations. JAK2 V617F mutation was associated with significantly increased levels of phosphorylated STAT5 and Akt in haemopoietic cells, most marked in megakaryocytes. In contrast, JAK2 exon 12 and MPL exon 10 mutations did not affect the level of phosphorylation. In systemic mastocytosis with KIT D618V mutation there was significantly increased expression of phosphorylated STAT5 and Akt in neoplastic mast cells although there was no change in the expression in other haemopoietic cells. JAK2 V617F is associated with upregulated phosphorylation of STAT5 and Akt in megakaryocytes, and to a lesser extent in other haemopoietic cells. Immunocytochemistry of bone marrow trephines for these phospho-proteins can be used as a supplementary diagnostic test with a high negative predictive value.

A novel monoclonal antibody for detection of folate receptor alpha in paraffin-embedded tissues.

Folate biochemical pathway components such as FR-alpha are determinants of response to novel antifolate drugs such as pemetrexed. Knowledge of their level of expression in tumors will enable their optimal use by identifying potentially responsive subgroups of patients. In spite of its importance in the diagnosis and treatment of cancer, monoclonal antibodies to FR-alpha suitable for immunohistochemical analysis of formalin-fixed and paraffin-embedded biopsy samples, or that can be used for Western blot analysis, are not available. The aim of this study was thus to generate a monoclonal antibody that could be used to detect specific expression of FR-alpha in paraffin-embedded tissues. A 189 amino acid region of the FR-alpha sequence was expressed as a recombinant fusion protein and used as antigen to generate monoclonal antibodies. Studies by ELISA and Western blot identified specific reactivity of the BN3.2 antibody to the recombinant protein and a single 40 kD protein in whole cell lysates from cell lines known to express FR-alpha. Immunohistochemical analysis of FR-alpha using hybridoma clone BN3.2 in a panel of normal tissues demonstrated expression limited to ovarian epithelia, placental trophoblasts, and proximal kidney tubules. Analysis of a panel of malignant and benign tissues demonstrated limited expression with variable intensities of staining and patterns of both membrane and cytoplasmic reactivity observed between cases. In the majority of malignant ovarian tumors, high intensity staining was observed, predominantly localized to the plasma membrane. Our results show that clone BN3.2 is a sensitive tool for detection of FR-alpha in paraffin-embedded tissues. This preliminary study also supports its use in immunohistochemical studies to determine the role of FR-alpha as a tumor prognostic marker and a possible therapeutic target.

Wild-type estrogen receptor beta expression in normal and neoplastic paraffin-embedded tissues.

Recently, several antibodies have allowed the detection of estrogen receptor beta (ER-beta) in paraffin-embedded tissue; however, these attempts have failed to specifically identify the wild-type form and revealed technical difficulties such as the necessity for alterations to standard staining protocols and amplification detection systems. The aim of this study was to generate a monoclonal antibody that could provide enhanced sensitivity for detection of ER-beta in paraffin embedded tissues. A 130-amino acid region of the C-terminus of ER-beta was expressed as a fusion protein and used as an antigen to generate monoclonal antibodies. Immunohistochemical analysis of ER-beta using clone EMR02 in normal and inflamed tissues demonstrated nuclear staining. In benign and malignant tumors, variable intensities of staining and patterns of nuclear reactivity were observed between cases. Intense ER-beta positivity was also observed in tumor-infiltrating lymphocytes. Mapping studies by ELISA and Western blotting have identified specific reactivity of EMR02 to a 17-amino acid sequence of the full-length wild-type ER-beta protein (ERbetawt). Our results show that clone EMR02 is a sensitive tool for the detection of ERbetawt in paraffin-embedded tissues. This preliminary study also supports its use in immunohistochemical studies to determine the role of ERbetawt as a tumor prognostic marker and a possible therapeutic target.

Detection of pneumolysin in sputum.

Western blot detection of the species-specific pneumococcal product, pneumolysin (SPN), was shown to be almost as sensitive as PCR for the non-cultural detection of pneumococci in 27 Streptococcus pneumoniae culture-positive sputa from patients stated to have chest infections. Both techniques were considerably more sensitive than counter-current immuno-electrophoresis for pneumococcal capsular polysaccharide antigens (CPS-CIE) on the same specimens. Sensitivities for PCR, SPN-immunoblotting and CPS-CIE were 100%, 85% and 67%, respectively. In 11 S. pneumoniae culture-negative sputa taken from patients receiving antibiotics, but with proven recent pneumococcal infection, PCR and SPN-blot were positive in six (in two of which CPS-CIE was also positive), PCR alone was positive in one and SPN-blot alone was positive in one. In 11 S. pneumoniae culture-negative samples from patients not receiving antibiotics, all three tests were negative in eight, PCR was positive in three (in one of which CPS-CIE was also positive), but SPN-blot was negative in all 11. In 16 S. pneumoniae culture-negative samples from patients receiving antibiotics and with no known recent pneumococcal infections, one or more non-cultural test was positive in 11. Although further evaluation is required to assess the significance of pneumolysin detection in relation to carriage and infection and to devise a more suitable test format, these preliminary studies suggest that pneumolysin detection is a promising new approach to the non-cultural diagnosis of pneumococcal chest infection.