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Lysozyme [EC 3.2.1.17] derived from hen egg white stimulated immunoglobulin production by human-human hybridoma, HB4C5 cells producing human lung cancer specific monoclonal IgM. IgM production by HB4C5 cells was enhanced more than 13-fold by the addition of lysozyme at 380 μg/ml in a serum-free medium. The immunoglobulin production stimulating effect of lysozyme was observed immediately after inoculation and maintained for 5 days. Lysozyme enhanced immunoglobulin production by the hybridoma line without growth promotion. This enzyme also accelerated IgM and IgG production of human peripheral blood lymphocytes 5.3-fold and 2.3-fold, respectively. These results suggest that lysozyme stimulates immunoglobuling production of not only specific hybridoma line, but also non-specific immunoglobulin producers. However, although the enzymatic activity of lysozyme was almost lost by heat-treatment at 100 °C for 30 min, the IPSF activity was retained. This fact suggests that IPSF activity of lysozyme does not come from its enzymatic activity or reaction products. All these findings clearly indicate that lysozyme has a novel function as an immunoglobulin production stimulating factor. GAPDH - glyceraldehyde-3-phosphate dehydrogenase; Ig - immunoglobulin; IPSF - immunoglobulin production stimulating factor; PBL - peripheral blood lymphocytes; HPLC - high-performance liquid chromatography.

At the time of operation, 10 patients with bladder tumors were given an intravenous infusion of bromodeoxyuridine (BrdU, 250 mg) to label the cells in the DNA synthesis phase (S-phase). The removed tumor specimens were stained immunohistologically using anti-BrdU monoclonal antibody. The percentage of BrdU-labeled cells (S-phase cells) were calculated for each specimen, and expressed as Labeling Index (LI). The average LI of G1, G2 and G3 tumors were 0.9%, 2.3% and 11.9%, respectively. LI was almost parallel to pathological grade. In cases of G2 tumor, LI was varied from 0.2 to 6.2%. The higher LI, the more invasive was the tumor. The patient with the highest LI (12.2%) showed lung metastasis postoperatively and died 6 months after operation. S-phase cells were scattered along the basal layer in G1 papillary tumors, and were observed also near the superficial layer in G2 tumors. In cases of non-papillary tumors, S-phase cells were observed irregularly in various layers. This method will give us useful information on evaluation for malignancy and cell kinetics of bladder tumor.

Abstract. The relationship between relative rates of DNA synthesis and DNA content in Bloom's syndrome fibroblasts (BS cells) was investigated by flow cytometry. The cells were pulse labelled with 5‐bromo‐2′‐deoxyuridine (BrdU). The BrdU content and cellular DNA content of individual BS cells were simultaneously measured by flow cytometry in which the cells were double‐stained by a FITC‐conjugated anti BrdU monoclonal antibody (mAb) for the BrdU content (green) and by PI (propidium iodide) (red) for total DNA content. Their red fluorescence histograms were analysed by a microcomputer to evaluate the cell fractions of each S compartment. The BrdU uptake in the early S phase of BS cells was lower than that of normal cells (fibroblasts from skin of a normal human), whereas the uptake in the middle and late S phase was essentially the same as that of normal cells. The early S phase in BS cells accounted for over 50% of the S phase cells. These findings suggest that, in comparison with normal cells, the rate of DNA synthesis in the early S phase of BS cells is lower, but is identical to controls in the middle and late S phases.

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