Comparison of two LED fluorescence microscopy build-on modules for acid-fast smear microscopy.

SETTING: National Reference Laboratory, Benin. OBJECTIVES: To compare the performance of Fraen FluoLED and LW Lumin light-emitting diode (LED) fluorescence microscopy modules. DESIGN: Acid-fast bacilli (AFB) smears, routinely examined with a classical fluorescence microscope, were blindly re-read with both LED systems at 200x magnification. Smears with discordant results were rechecked on all systems at 200x, and 100 randomly chosen smears were read again at 400x. Confirmed presence of AFB with any system was accepted as a true positive. RESULTS: A total of 1937 smears were examined by all systems. The Fraen and LW detected 895 (46.2%) and 817 (42.2%) positive and scanty positive smears. After rechecking 201 smears, 15 false-positive and 61 false-negative results were declared for Fraen, against 11 and 135 for LW. The systems had similar false-positive rates (1.7% for Fraen and 1.4% for LW), but differed significantly regarding detection of confirmed microscopy positives (93.5% and 85.6% respectively, P < 0.00001). A high correlation between both LED systems was found at 400x magnification. CONCLUSIONS: The Fraen LED fluorescence microscopy module performed significantly better than the LW LED at the most efficient 200x magnification. It was also more appreciated by all users. The LW module may perform equally well at higher magnification.

Natural killer activity of peripheral blood lymphocytes and its relation to histopathological factors of lung cancer.

This investigation was intended to determine whether the natural killer (NK) activity of peripheral blood lymphocytes (PBL) correlated with the histopathological factor, which is thought to be a result of a balance between tumor aggression and host resistance. The NK activity of PBL from 60 patients with lung cancer was measured by the lysis of 51Cr-labelled K562 target cells. The activity was significantly decreased with advancing stages of the disease, and inversely correlated with increased immunosuppressive substance levels of the serum. Histopathological factors, such as low grade pleural invasion of the tumor and abundant lymphoid cell infiltration around the tumor, were significantly associated with the high NK activity of PBL. These results show that a decrease in NK activity may play a role in identifying those individuals with a greater risk of cancer development.