Effect of AET treatment of sheep erythrocytes on the rosette test in various diseases.

180 patients with neurological or infectious diseases and 90 normal controls were examined for blood T lymphocyte percentage by the standard method using rosette formation with untreated sheep erythrocytes (E) and a technique using 2-amino-ethyl-thio-isouronium bromide hydrobromide (AET)-treated E, with fetal calf serum (FCS) in the medium. Patients with acute meningitis had a decrease and those with infections mononucleosis had an increase in T lymphocyte percentage as measured by both assays. However, patients with active MS and with cerebral tumours had a decrease in T cell percentage by the E but not by the EAET technique. The T lymphocyte percentages of the other 4 patient groups did not differ significantly from those of the controls, regardless of the technique used. In certain diseases, the use or not of AET-treated indicator cells may thus influence the results of the rosette test.