The expression of CD4 and CD8 molecules conditions the behavior of V beta + murine thymocytes upon superantigenic challenge.
We investigated the capacity of the Staphylococcal enterotoxin (SE) B, a superantigen (SAg) specific for TCR V beta domain, to modulate V beta 8+ thymocytes selection in adult mice. Thymocytes were collected at various time intervals after SEB injection (10 and 100 micrograms) and V beta 8+ modulation was analysed by three color flow cytometry. SEB failed to affect V beta 8+ thymocytes comprised in the less mature compartments, namely, CD4+8+ and CD4-CD8-, whereas it selectively affected V beta 8+CD4+8+ (downward modulation) and V beta 8+CD4-8+ thymocytes (upward modulation). The different response to SEB challenge between CD4+8- and CD4-8+ thymocytes appeared dependent on the CD4/MHC class II interaction, as V beta 8+CD4-8+ thymocytes carrying a transgenic CD4 molecule capable of interacting with MHC class II showed the same response of V beta 8+CD4+8- thymocytes. At variance with thymocytes, however, V beta 8+CD4+8- and V beta 8+CD4-8+ splenic T lymphocytes responded to SAg challenge in identical manner (upward modulation) highlighting the importance of maturation status and/or microenvironment in SAg response. V beta 8+ thymocytes remaining in the thymus were assessed for their capacity to respond to a SAg challenge. Thus, thymocytes were obtained at various time intervals after SEB injection and cultured in the presence of SEB or SEA, a Sag specific for V beta 10 as control. A reduced mitotic response to SEB but not to SEA was noticed irrespective of the number of V beta 8+ responding cells present in culture. It is concluded that SAgs affect TCR specific thymocytes by conditioning their redistribution and inducing an anergic status.
Fattorossi
A
A
Laboratory of Immunology, D.A.S.R.S., Rome, Italy.
Baschieri
S
S
Ferlini
C
C
Doria
G
G
D000818:Animals; D015704:CD4 Antigens / Q000378:metabolism*; D016827:CD8 Antigens / Q000378:metabolism*; D004768:Enterotoxins / Q000008:administration & dosage / Q000276:immunology; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism*; D018089:Superantigens / Q000008:administration & dosage*; D016176:T-Lymphocyte Subsets / Q000276:immunology*
D015704:CD4 Antigens; D016827:CD8 Antigens; D004768:Enterotoxins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D018089:Superantigens; C031818:enterotoxin B, staphylococcal