Stability of E-rosettes in aged humans: Effect of cytochalasin B and colchicine

Abstract

A greater stability of E-rosettes and a reduced rate of capping of sheep erythrocytes are observed in elderly people. The lack of qualitative changes in the sensitivity of these processes to colchicine and cytochalasin B suggests that the function of the microfilaments and the microtubules is not primarily affected by ageing. The density and the affinity of the lymphocytes for sheep erythrocytes do not decrease in aged subjects. So the defective rearrangement of the E-receptors cannot be accounted for by some receptor alteration but points to a possible hindrance of their cross-linking in the membrane or their submembrane connection to the cytoskeleton.

Sheep-erythrocyte-capping by human T-lymphocytes. pharmacological inhibition by phenothiazine drugs

“…However, though this pharmacological profile is quite suggestive of a calmodulin-mediated process, it remains hypothetical since the specificity of the phenothiazines has been questioned (Corps, Hesketh & Metcalf, 1982) and other phenothiazine-sensitive proteins like calcimedins have been described (Moore & Dedman, 1982). Contrary to other récent studies (Salisbury et al, 1981;Nelson et al, 1982), stressed that the SRBC-capping process has a rather slow kinetic (Brohée et al, 1982(Brohée et al, , 1983 while quite sensitive to phenothiazines, a finding in contradiction with previous views about capping of class I and II surface macromolecules (Braun et al, 1978;Braun & Unanue, 1983). This may suggest a looser link of the SRBC receptors to the cytoskeletal proteins than needed for a perceptible accumulation of calmodulin.…”

“…Bell (Smith, K hne and RIT). Stock solutions were prepared in saline at 10"^M and kept Capping E-rosettes (SRBC:PBL ratio 50:1) were prepared by centrifugation (1000 rpm, 10 min, 22°) in protein free RPMI and overnight incubation at 4°C as previously reported (Brohée et al, 1982(Brohée et al, , 1983. After gentle resuspension, aliquots of 200 were withdrawn and mixed with 100 (A of médium with or without drug at the desired concentration.…”

Specific Effect of Age on Lectin-Induced Mitogenesis of Lymphocytes from Diseased Patients

“…Hindrance of SRBC capping in elderly subjects has been emphasized in previous studies |2, 3]. Altered capping of other sur face receptors has also been described [18,22].…”

“…helper and OKT8, suppressive-cytotoxic subsets [1]. Capping of sheep erythrocytes (SRBC) was studied as previously defined [3], In brief, after 200 g centrifugation and overnight incubation at 4°C in serum-free medium, E-rosettes (lymphocytc:SRBC ra tio 1:50) were resuspended and incubated at 37 °C for 15 min. The percentage of capped cells relative to the number of still formed rosettes was recorded as the capping rate (CR).…”

“…In the present study, deliberately address ing a diseased population departing from the optimally defined healthy subjects, we tried to determine the real importance of age on the lymphocyte response to phytohemagglu tinin A (PHA) taking into account variables such as sex, lymphocyte subsets and a lym phocyte membrane functional marker re cently described (sheep erythrocyte capping [2,3]). …”