Regression coefficient analysis of neutrophil chemotaxis in periodontitis

Micropore-filter techniques have been widely used to assess motility and chemotaxis of neutrophils. In some cases the results were impaired by inadequate methods of evaluation and failures of the test system. For clinical purposes the mode of test evaluation should be able to differentiate between failures of the test system (false-negative) and real functional defects (true-negative). A new method has been developed to check parallel assays for homogeneity. Based on earlier procedures this type of evaluation uses the comparison of regression coefficients to identify false-negative test results within the cell population of an individual. The newly developed method was used to study the chemotactic response in a group of 49 patients and 22 healthy volunteers. Intraclass correlation coefficients of the regression coefficient analysis and the leukotactic index were calculated and compared. It could be demonstrated that the regression coefficient analysis had the same sensitivity as the leukotactic index. Slight variations in the cell counts at a single plane of the chemotactic filter affecting the leukotactic index by 18% had no measurable influence on the calculated regression coefficient.