Interleukin 1-induced down-regulation of antibody binding to CD4 molecules on human lymphocytes.
Interleukin 1 (IL-1) is involved in the early activation of T lymphocytes. The CD4 antigen, described as a phenotypic marker of helper T cells, is also important in early T-cell activation by its ability to bind to MHC class II molecules on antigen-presenting cells, and to transmit positive (and negative) signals to the cells. We observed that purified human monocyte IL-1 as well as recombinant IL-1 alpha and IL-1 beta selectively decreased the binding of monoclonal antibodies to CD4 on the surface of otherwise unstimulated blood T cells, in contrast to prestimulated and continuously grown CD4+ cells. Under optimal growth conditions, the initial reduction in antibody binding to CD4 was followed by an apparent re-expression of the CD4 antigen even in the presence of high concentrations of IL-1. This re-expression did not occur if the cells were cultured at 4 degrees C, or after treatment with actinomycin D or cytochalasin B, indicating that protein synthesis and intact microfilament function were essential for re-expression of CD4 binding. The mechanism by which CD4 molecules are physically and/or functionally modulated by IL-1 is unclear.
Tvede
N
N
Laboratory of Medical Immunology, Rigshospitalet University Hospital, Copenhagen, Denmark.
Christensen
L D
LD
Odum
N
N
Wiik
A
A
Bendtzen
K
K
D000911:Antibodies, Monoclonal / Q000276:immunology; D000937:Antigen-Antibody Reactions; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology*; D007518:Isoantibodies / Q000276:immunology; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D007375:Interleukin-1; D007518:Isoantibodies