Stages of T cell activation: continued antigen dependence of IL 2-producing cells after IL 2 receptor expression.
Alloantigen stimulation leads, within 48 to 72 hr, to the expression of IL 2 receptors (IL 2R) on the surface of most of the helper T cells with specificity for the stimulating antigens. The IL 2R-bearing cells, separated by flow cytometry from 3-day human or mouse mixed lymphocyte cultures, were found by limiting dilution methods to be enriched 10- to 20-fold (compared to IL 2R- cells) for antigen-specific helper T cells detected by IL 2 production. Although these cells have been activated to an IL 2R+ stage, most of them are unable to produce detectable IL 2 unless they are cultured together with the original, activating antigen. Even when IL 2 is supplied, and lymphokine production measured by assay of a second factor, IL 3, the large majority of individual activated helper T cells remain dependent on further antigenic exposure for their continued maturation into lymphokine-secreting effectors. Helper T cells at this early stage of activation can therefore proliferate when given IL 2 alone, but lymphokine secretion involves a second antigen-dependent step.
R A
RA
Miller
M K
MK
Rozans
A A
AA
Ythier
T B
TB
Strom
D000818:Animals; D002469:Cell Separation; D003429:Cross Reactions; D000939:Epitopes; D006183:H-2 Antigens / Q000276:immunology; D064532:Histocompatibility Antigen H-2D; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis* / Q000378:metabolism / Q000502:physiology; D007519:Isoantigens / Q000276:immunology*; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D011971:Receptors, Immunologic / Q000096:biosynthesis* / Q000502:physiology; D015375:Receptors, Interleukin-2; D006377:T-Lymphocytes, Helper-Inducer / Q000145:classification / Q000276:immunology / Q000378:metabolism*; D013997:Time Factors
D000939:Epitopes; D006183:H-2 Antigens; D064532:Histocompatibility Antigen H-2D; D007376:Interleukin-2; D007519:Isoantigens; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2