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BACKGROUND: Circulating heterophilic antibodies interfere with immunological assays in laboratory examinations; however, their rate of incidence is currently questionable. We developed an enzyme-linked immunosorbent assay (ELISA) to detect human anti-mouse antibodies (HAMAs) in routine examinations. METHODS: The study samples were comprised of serum samples obtained from 290 inpatients and outpatients at our hospital. Mouse immunoglobulin G1 (mIgG1), mIgG2a, and mIgG2b were used as the antigens and horseradish peroxidase (HRP)-conjugated anti-human IgG and IgM were used to identify the HAMA isotype. RESULTS: HAMAs were detected in 11.7% (34/290) of the samples. We observed 18 and 20 samples positive for IgG- and IgM-type HAMAs, respectively. Four samples contained both IgG- and IgM-type HAMAs. HAMAs against mIgG1, mIgG2a, and mIgG2b were found in 21, 14, and 13 samples, respectively. Existence of HAMAs was confirmed by western blotting using mIgG's as the antigens and HAMAs as the primary antibodies. Heterophilic blocking reagent (HBR) was also used to block the heterophilic interactions. Unexpectedly, a low HBR concentration rather enhanced the interactions instead of blocking them. CONCLUSIONS: A considerable number of HAMA-positive samples, reacting with the heavy chain of mIg, were found in routine examinations. A sufficient amount of HBR should be used for blocking the heterophilic interactions.

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Overexpression of the olfactomedin 4 (OLFM4(GW112,/hGC-1)) gene was recently reported to inhibit various apoptotic pathways and promote proliferation of cancer cells, suggesting that OLFM4 might serve as a diagnostic marker for human cancers. Therefore, we examined cancer-specific OLFM4 overexpression. OLFM4 mRNA was highly expressed in cancerous tissues obtained from the colon, breast and lung. Positivity for OLFM4 mRNA, defined as the mean + 2 SD in non-cancerous colon and breast tissues, was observed in 68 and 50% of the studied colon and breast cancer tissues. OLFM4 mRNA expression was not detected in non-cancerous lung tissues but was evident in 62% of the lung cancer tissues. On comparing paired samples, the expression of OLFM4 mRNA was observed to be elevated in 90, 69 and 85% of colon, breast and lung cancer tissues, respectively. OLFM4 mRNA expression was observed even in the early stages of each cancer type. The expression of OLFM4 mRNA did not correlate with that of the antiapoptotic molecule survivin, indicating that it can be used independently in cancer diagnosis. Combining OLFM4 and survivin resulted in higher positivity. Thus, OLFM4 mRNA might be a useful tool to support the diagnosis of cancer, irrespective of the clinical stages.

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Induction of olfactomedin 4 (OLFM4(GW112/hGC-1)) in cancer cells was recently reported to have a novel antiapoptotic action via binding to the potent apoptosis inducer GRIM-19. We sought to clarify undiscovered functions of constitutively expressed OLFM4 in cancer cells. OLFM4 mRNA was highly expressed in pancreatic cancer tissues. In PANC-1 cell cultures, expression was especially elevated during early S phase of the cell cycle. Transduction of small interfering RNA for OLFM4 to decrease mRNA expression caused time-dependent growth inhibition, with typical early S-phase arrest after 6 days. In addition, cell volume increased without increases in multinucleated cells, consistent with premitotic inhibition of DNA synthesis. Inhibition of OLFM4 mRNA expression by small interfering RNA did not promote apoptosis. Taken together, the results indicate that OLFM4 promotes proliferation of PANC-1 cells by favoring transition from the S to G(2)/M phase.

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BACKGROUND: Although prewarming (PW) can reduce the confounding agglutination of cold-reactive antibodies when testing for warm-reactive antibodies, PW also can adversely affect the detection of warm-reactive antibodies. This study was conducted to determine PW conditions that optimized Rh antibody detection. STUDY DESIGN AND METHODS: In 38 plasma samples with Rh system antibodies detected by any of four methods, and in 8 other samples with cold-reactive antibodies, reactivity was assessed by titer and score. RESULTS: PW to 37 degrees C often reduced reaction scores by all methods especially the low-ionic-strength saline indirect antiglobulin test and bromelin methods. In analyses warming red blood cell (RBC) suspensions or plasma, the reaction scores were decreased only when the RBC suspension was warmed, suggesting that RBC PW decreased Rh antibody reactivity. The warming period ranging from 5 to 30 minutes all decreased Rh system reaction scores, an effect persisting up to 120 minutes. At lower temperatures (27, 30, and 33 degrees C), numbers of samples showing decreased reaction score for Rh system antibodies decreased in a temperature-dependent manner. Testing at 27 degrees C also permitted some agglutination involving cold-reactive antibodies, whereas higher temperatures successfully suppressed their agglutination. CONCLUSION: PW at 30 degrees C minimizes problems in accurately detecting Rh system antibodies.

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