Accessory cells and T cell activation. The relationship between two components of macrophage accessory cell function: I-A and IL1.
Accessory cells are required for the activation of helper T cells. We have examined two characteristics of accessory cells, their expression of I-A, and their ability to release IL1. We provide evidence that these two properties are related, and postulate that membrane I-A molecules participate in the pathway leading to IL1-release. Experimental results are described relating I-A to IL1-release as follows: 1. In vitro-educated Ly1 T cells stimulate IL1-release from M phi; this process is H-2-restricted and blocked by anti-I-A antibodies. 2. H-2-restriction between T cells and M phi is overcome in the presence of ConA, but this unrestricted interaction is also blocked by anti-I-A. 3. LPS stimulation of IL1-release is blocked by anti-I-A. These findings suggested an active role for I-A molecules on IL1-producing cells. We next describe a series of experiments designed to assess the requirements for I-A versus IL1 during T cell activation. In a number of experimental systems, T cells demonstrated a requirement for I-A-recognition, but none that could not also be satisfied by IL1: 1. Generation of helper T cells in allogeneic chimeras. 2. Proliferation of KLH-primed lymph node cells. 3. Proliferation of KLH-primed lymph node cells from chronically anti-I-A-suppressed mice. 4. Proliferation of GAT-primed lymph node cells from nonresponder mice. These findings suggest that for many kinds of T cells (not necessarily all) the apparent requirement for I-A-recognition is primarily involved in stimulating IL1-release from accessory cells.
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology*; D006183:H-2 Antigens / Q000276:immunology; D006433:Hemocyanins / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D007375:Interleukin-1 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D010455:Peptides / Q000276:immunology; D011108:Polymers; D013601:T-Lymphocytes / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology
D006183:H-2 Antigens; D000949:Histocompatibility Antigens Class II; D007375:Interleukin-1; D010455:Peptides; D011108:Polymers; C020749:GAT; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin