Cellular mechanisms in delayed hypersensitivity. Part 2.

UK : University of London, 1973.

1 encoded moving image (26 min.) : sound, black and white.

00:26:04

University of London

CC-BY-NC

In English

Presented by Professor John Turk. Made by University of London Audio-Visual Centre for the British Postgraduate Medical Federation. Produced by David Sharp.

This video is one of around 310 titles, originally broadcast on Channel 7 of the ILEA closed-circuit television network, given to Wellcome Trust from the University of London Audio-Visual Centre shortly after it closed in the late 1980s. Although some of these programmes might now seem rather out-dated, they probably represent the largest and most diversified body of medical video produced in any British university at this time, and give a comprehensive and fascinating view of the state of medical and surgical research and practice in the 1970s and 1980s, thus constituting a contemporary medical-historical archive of great interest. The lectures mostly take place in a small and intimate studio setting and are often face-to-face. The lecturers use a wide variety of resources to illustrate their points, including film clips, slides, graphs, animated diagrams, charts and tables as well as 3-dimensional models and display boards with movable pieces. Some of the lecturers are telegenic while some are clearly less comfortable about being recorded; all are experts in their field and show great enthusiasm to share both the latest research and the historical context of their specialist areas.

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

Segment 5 Turk continues to discuss lymphocytes and tests on sensitised animals. He also talks about the Jones-Mote reaction, another type of hypersensitivity reaction. A graph compares the effect of cyclophosphamide on Jones-Mote reactions and on tuberculin-type sensitivity and Turk explains the data. He concludes the lecture by summarising the points made throughout. Time start: 00:19:53:13 Time end: 00:26:04:19 Length: 00:06:11:06