Characteristics of the 'active rosette test'. I. Technical considerations of the test and comments.

Using normal subjects, it was found that the 'Active Rosette Test' is both reproducible and consistent if performed exactly as described by Wybran et al. (1972). Variations in incubation time, centrifugal force while sedimenting rosettes, resuspension time after centrifugation, SRBC lymphocyte ratio, and increasing concentrations of fetal calf serum all produced marked deviations in test results. Rosette inhibition studies using a specific anti-T cell antisera showed inhibition of 'active' and total rosettes at the same level, suggesting that there are no marked variations in surface T antigens among respective T cells. Unless differences in functional activities can be demonstrated between the 'active' rosette-forming cells and the other T cells, the test will be of an empiric nature.