Description: Segment 1 Turk introduces the subject, differentiating it from a previous lecture which looked at B-lymphocyte reactions this lecture will focus on T-lymphocyte reactions. He shows a diagram detailing possible changes to bone marrow lymphocytes when affected by T-lymphocytes. Turk then shows a series of tables listing delayed hypersensitivity reactions to microbial protein antigens followed by tables comparing Arthus reactions and tuberculin antigens in terms of their reaction to T-lymphocytes. Time start: 00:00:00:00 Time end: 00:06:51:00 Length: 00:06:51:00 Segment 2 Turk uses a diagram with moveable pieces to show the mechanism of sensitisation to an invading body. He describes all immune reactions as being like a reflex arc which becomes complicated as more physiological systems become involved. Next he shows an illustration of a lymph node and a histogram of a lymph node with depleted T-lymphocytes. Time start: 00:06:51:00 Time end: 00:10:26:00 Length: 00:03:35:00 Segment 3 Turk shows an illustration of a lymph node with a proliferation of T-lymphoyctes, then autoradiographs of the same. He refers to a diagram comparing cell-mediated immunity with humoral antibody production and a graph detailing the pieaks of lymphocyte proliferation. After this, he returns to the diagram with moveable pieces and makes it more complex. Time start: 00:10:26:00 Time end: 00:17:10:00 Length: 00:06:44:00 Segment 4 Turk shows slides and graphs relating to how macrophages function in tissue culture. He describes their function in detail. Time start: 00:17:10:00 Time end: 00:20:04:00 Length: 00:02:54:00