Description: Segment 1 Prof. Turk summarises Part One of his lecture on cellular mechanisms in delayed hypersensitivity and says that in Part Two he will be discussing the mechanism by which the specifically sensitised lymphocytes release pharmacological agents that can cause inflammatory reactions, and how these inflammatory reactions are dependent on the activation of macrophages. He then discusses the macrophage, a key cell in a delayed hypersensitivity reaction. Slides of lysosome particles and macrophages are seen as Turk discusses their roles in delayed hypersensitivity reaction. A picture of the migration of macrophages from a capillary tube is seen. Time start: 00:00:00:00 Time end: 00:05:05:10 Length: 00:05:05:10 Segment 2 Turk discusses an experiment on a guinea-pig (seen in a photograph), which was injected with the culture supernatant from an incubation between sensitised lymphocytes and antigen. He also addresses increased vascular permeability in such an experiment, and how to measure this by injecting blue dye intravenously. A graph shows the relationship between the area of blueing, the increased vascular permeability and the concentration of the culture supernatant injected. He then talks about skin reactive factor, migration inhibitory factor and lymphotoxin. Tables show the chemical characteristics of macrophages and the ways in which such material can be released into a culture supernatant. Turk then focusses on lymphocytes and how they release pharmacological agents. Time start: 00:05:05:10 Time end: 00:09:57:06 Length: 00:04:51:21 Segment 3 Prof. Turk continues to discuss lymphocytes and how they release pharmacological agents. Charts show three ways: with tuberculin, a soluble antigen that sensitises lymphocytes with Concanavalin A, the phytomitogen from normal lymphocytes with sheep red cells from sensitised lymphocytes. Turk explains how specifically sensitised lymphocytes are produced and also talks about the effects of these pharmacological agents on macrophages. Photomicrographs of macrophage cultures are seen before and after incubating with culture supernatant. He then discusses enzyme activity within macrophages and how to study enzyme activity using histochemical techniques. Diagrams explain these techniques. Time start: 00:09:57:06 Time end: 00:14:24:01 Length: 00:04:26:20 Segment 4 Turk talks about how macrophages can also be studied by looking at the electrostatic charge on their surfaces (results seen in a table). He also discusses how concurrent B-lymphocyte stimulation can module T-lymphocyte function in the production of delayed hypersensitivity reactions. Photomicrographs of the lymphocytes are seen. He mentions an experment on guinea-pigs in which skin reaction is observed after sensitisation. Time start: 00:14:24:01 Time end: 00:19:53:13 Length: 00:05:29:12