Immune disorders: Lecture 5
Graft v. Host Disease
doctor can use bone marrow to transplant; called an allograft
the donated T cells get looked at as foreign
the immune response kicks in
if MHC I molecules are different it causes the graft t cells to attack all the recipients tissues and create destructive lesions
if type II MHC molecules are diff. the graft T cells attack the host and the APC's of the host lead the immunosuppression and leave body open to infection
Donor/Tissue Typing
MHC compatibility is hard due to the variability
the more closely related you are to the recipient the better; look for a twin and others
tissue typing
used to find the perfect donor for the recipient
look at wbc to see how closely they match for the graft
if the match is 50% and less different then the better the chance of being accepted by the recipient
Immunosuppressive Drugs
they are important to the success of modern transportation and effective combating of certain autoimmune diseases
their are 4 types
Glucocorticoids
also called steroids
prednisone and methylprednisolone suppress the response of T cells to the antigen and stop mechanisms as T cell cytotoxicity and cytokine produce
Cytotoxic Drugs
stop mitosis and cytokinesis (cell division)
Cyclophosphamide
cross links daughter DNA molecules in mitotic cells
stops their separation and blocks mitosis
impairs B and T cell responses
Azathioprine
it competes with purines during the making of nucleic acids
blocks DNA replication and suppresses both primary and secondary antibody responses
Cyclosporine
a polypeptide that comes from fungi, and prevents making of interleukins and interferons by T-cells
ends up blocking Th1 responses
less toxic
usually combined with glucocorticoids
Lymphocyte-depleting therapies
type of therapy attempts to reduce many adverse side effects associated with immunosuppressive drugs
technique involves administering an antiserum called anti-lymphocyte globulin thats specific for lymphocytes
Autoimmune diseases
appear to come spontaneously and at random
noted features: occur in elderly, more common in men than in women, and results when an individual begins to make antibodies or cytotoxic T cells against body cells
Why they occur?
estrogen may stimulate destruction of tissue by cytotoxic T cells
some maternal cells may cross placenta, colonize fetus, trigger autoimmune diseases later in life
fetal cells may cross placenta and trigger autoimmunity of mothers
environmental factors; viral infectionhe immune system
genetic factors; certain MHC genes
T cells may encounter self-antigens that are normally "hidden"
microorganisms may trigger autoimmunity due to molecular mimicry
failure of normal control mechanisms of