Photographic, stereological and statistical methods in evaluation of aggregation of red cells in disease: Part I: Kinetics of aggregation

: Kinetics of red cells aggregation were studied by microphotography of blood contained between parallel-plates in a slit of 12.5 micrometers. Blood samples, anticoagulated with EDTA, were adjusted to haematocrit of 0.30 using native plasma. Blood was allowed to flow at shear rate of 2000 sec-1, flow was stopped, and sequential photography carried out. Full development of aggregation required from 2 to 10 minutes, depending on the blood sample. Blood studied included normal donors and patients with polycythaemia, lymphoma, hyperparathyroidism, Waldenstrom's macroglobulinaemia, influenza. The quantitative evaluation of colour slides was carried out on Microvideomat No. 2 with Zeiss Interference Monochromator, using light wave length of 460 or 560 nanometers. The stereological parameters defined included d(Heyn), Lamda, and S/V. Linear regressions of stereological parameters against square root of stasis time showed correlation coefficients of 0.8 up to 0.99. Linear regressions for different blood samples were compared, and significance of differences between slopes or between elevations was defined using F-distribution. Such differences were significant up to P less than 0.001. Rate of aggregation was much higher in macroglobulinaemia or lymphoma than in normals, and it was lowest in the hyperparathyroid disease.