Answer
See solution
Work Step by Step
# similarities :
i- both SCIKD and AIDS cause severe immunodeficiency leaving the body
subjected to infection with Opportunistic organisms ( viral, bacterial, fungal.
and protozoal ).
ii- development of cancer due to concomitant EBV infection in both cases.
# Dissimilarities :
A- SCID :
- primary immunodeficiency.
- congenital defects in the development of the cells of the
immune system.
- failure of differentiation of stem cells into T and B cells.
- treated by bone marrow grafting.
B- AIDS :
- secondary immunodeficiency.
- viral infection ( acquired ) by Human Immunodeficiency
Virus ( HIV ).
- HIV attacks CD4 helper T cells leading to their depletion.
- controlled by Antiviral drugs
e.g Azidothymidine ( AZT ), dideoxyinosine ( ddI ), deoxythiacytidine ( 3 TC )
and stavudine ( d4T ).
Severe Combined Immunodeficiency ( SCID )
- this may be due to failure of differentiation of stem
cells into T and B cells
however the explanation of this failure is not known.
- both humoral and cell mediated immunity are
deficient.
- these infants suffer from all kinds of opportunistic
infections : viral, bacterial, fungal and protozoal.
- death occurs early in childhood ( before 1 year ).
- the disease may be inherited in an X-linked
recessive or autosomal recessive manner, however
sporadic forms occur.
# Immunologic Findings :
1- Hypoplasia of the Thymus as shown by chest
X-ray.
2- Lymphopenia and decreased T cell number and
functions:
- impaired response to Phytohemagglutinin
( PHA ).
- Impaired Delayed Hypersensitivity reactions.
3- Decreased B cell number and function :
- Serum Immunogloulins are absent or decreased
- No response to antigenic stimuli.
# Treatment :
patients may be made completely normal by grafting
with histocompatible bone marrow from a sibling.
incompatible grafts will lead to a fatal " graft versus
host " ( GVH ) reactions.
- Gammaglobulins may be administered.
- Antibiotics are used for treatment of infections.
Epstein-barr virus ( EBV )
- EBV is the causative agent of infectious mononucleosis
- it is one of the tumor viruses.( causal relation
between EBV and human cancer ).
- it is associated with Burkitt s Lymphoma,
Nasopharyngeal Carcinoma ( NPC ) and
lymphoproliferative disorders in immunodeficient
individuals.
Infectious Mononucleosis
- EBV is transmitted by infected saliva.
- infection starts in the oropharynx, then the virus
infects B lymphocytes which are tramsformed and
proliiferate.
- EBV remains latent in lymphocytes but viral antigens
are expressed e.g. nuclear antigen ( EBNA ).
these cells are rejected by activated T Lymphocytes.
this leads to appearance of atypical T Lymphocytes
in the peripheral blood.
- the disease manifests by fever, sore throat, enlarged
lymph nodes and spleen, rash may appear.
- it is a self limited disease.