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The philothermal response, i.e., the tendency of polymorphonuclear leukocytes (PMNs) to migrate along a temperature gradient toward warmer temperatures, was evaluated in 11 patients with a clinical diagnosis of dementia of the Alzheimer type (DAT) and compared to 11 age and sex-matched mentally normal individuals. While the total number of migrating PMNs did not differ significantly between these two groups, there was a significant difference in the spatial distribution of the responding cell population. The numerical parameter, R, has been introduced to provide a quantitative measure of the distribution of populations characterized by differences in motile behavior. This R value was unusually high for 10 of the DAT patients but only one of the comparison individuals. No relation between R and duration of illness, age, or sex was detected. These preliminary findings, based on a small number of clinically diagnosed DAT patients, suggest that the philothermal response may represent a biological marker with diagnostic usefulness for at least one subgroup of DAT patients.

The role of microtubules in the philothermal response of polymorphonuclear leukocytes (PMNs) was examined using colchicine, a known microtubule disrupting agent. Colchicine inhibited PMN migration in a dose dependent fashion. Spatial distribution analysis of the responding cell population revealed a preferential inhibition of distal cell migration, a pattern similar to that found for PMNs obtained from patients with dementia of the Alzheimer type (DAT). The result is consistent with the known role of microtubules in directed cell migration and the hypothesized microtubular defect in DAT. Further investigations of microtubules may provide insight into the etiology and pathogenesis of DAT.

A newly developed technique for quantitating the locomotion of polymorphonuclear leukocyte (PMN) populations in temperature gradients has revealed that PMNs accumulate toward higher temperatures. The experiments yield measurements of the numbers of cells that adhere to glass and migrate from a cell suspension through a liquid/gel meniscus into a glass/agarose interface, and of their spatial distribution at subsequent time intervals. Cell locomotion was investigated as a function of the magnitude, sign, and temporal variation of the temperature gradient, the cell concentration in the source suspension, and the presence or absence of chemoattractant gradients. It was found (1) that a temperature gradient stimulates crossing of the meniscus toward higher temperatures, (2) that only a portion of the cells reverses direction of locomotion in response to reversal of the temperature gradient after the cells have traversed the meniscus, and (3) that the distribution of cells in the migration space depends on cell concentration, suggesting that the dynamics of PMN locomotion depend on cell-cell interactions.