packet 12 Flashcards
built into cell membrane of all cells except red blood cells
MHC-I molecules
function of MHC
if cell is infected with virus MHC-I contain bits of virus marking cell so T cells recognize is problem
if antigen presenting cells (macrophages or B cells) ingest foreign proteins, they will display as part of their MHC-II
MHC-II markers seen only on membrane of
antigen presenting cells (macrophages, B cells, thymus cells)
bind to antigen in extracellular fluid
b cells
can only recognize fragments of antigens that have been processed and presented to them as part of a MHC molecule
t cells
“see” antigens if part of MHC-II molecules on surface of antigen presenting cell
helper t cells
“see” antigens if part of MHC-I molecules on surface of body cells
cytotoxic t cells
Foreign antigen in body fluid is phagocytized by
APC (macrophage, B cell, dendritic cell (Langerhans cell in skin)
Antigen is digested and fragments are bound to MHC-II molecules stuck into
antigen presenting cell membrane
APC migrates to lymphatic tissue to find
t cells
Small protein hormones involved in immune responses are secreted by
lymphocytes and antigen presenting cells
alpha-interferon used to treat Kaposi’s sarcoma, genital herpes, hepatitis B and C & some leukemias
beta-interferon used to treat multiple sclerosis
interleukin-2 used to treat cancer (side effects
Cytokine therapy uses cytokines (interferon)
Begins with activation of T cell by a specific antigen
Result is T cell capable of an immune attack
elimination of the intruder by a direct attack
cell-mediated immunity
Types of Mature T Cells
Helper T cells
Cytotoxic (killer) T cells
Memory T cells
Display CD4 on surface so also known as T4 cells or TH cells
Recognize antigen fragments associated with MHC-II molecules & activated by APCs
helper t cells