Primary immunodeficiency disorders. Flashcards
immunodeficiency can be classified into ?
specific immunodeficiency
non specific immunodeficiency
primary and secondary
what is the difference between specific and non specific immunodeficiency ?
specific immunodeficiency involve abnormalities of the b and cells of the adaptive immune system
non specific immunodeficiency involves abnormalities in the compliment system , neutrophils and phagocytes which is INNATE immunity
what is the difference between primary and secondary immunodeficiency
primary immunodeficiency is related genetics being the sole cause
while secondary immunodeficiency is triggered by environmental causes such as a bacteria
infections encountered in immundefcient patients falls into two categories what are these categories ?
patient with defect in antibodies and compliment proteins and phagocytes = susceptible to recurrent infections from capsulated bacteria such as h influenzas , strep yo, staph areas giving pyogenic infections
patient defect in cell mediated immunity from t cells are susceptible to severe life threatening infection from micro-organism which is ubiquitous in the environment = opportunistic infections
such as candida and chicken pox
what are the primary b cell immunodeficiencies ?
x linked agammaglobulinemia
Iga deficiency
IgG subclass deficiency
immunodeficiency with increased IgM
common variable immunodeficiency
transient hypogammaglobulinemia of infancy
which gender does x linked (bruton) agammaglobulinemia affect the most
males
in x linked agammaglobulinemia when do the signs and symptoms start to appear
6-12 month of life because they receive passive immunity from the IgG that crossed the placenta
what is the pathophysiology of x linked bruton agammaglobulinemia
the pre b cell do not go into an IMmature b cells so there is NORMAL amount of pre b cell in the bone marrow however absent to few B cells in the blood
this is due to a cytoplasmic bruton tyrosine kinase enzyme defect which is linked to the maturation of the b cells
the defect in the gene is in the LONG arm of the x chromosome
what are the signs of x linked bruton Agamma globulinemia
lymphoid hypoplasia - tonsils adenoid no splenomegaly or lymphadenopathy
Present with recurrent pyogenic infections with Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae
respiratory tract = sinusitis , otitis media and pneumonia ,
meningitis
no viral except : hepatitis virus hepatitis enterovirus (polio , coxsackie) = myositis , CNS infections echovirus
how do we diagnose x linked gamma globulinemia
history of recurrent infection mostly in the respiratory tract and lymphoid hypoplasia
blood test lack of b cells determined by CD19 and CD20 marker
= flow cytometry to show there an no mature b cells circulating
ABSCENCE OF CD19 B CELLS PARTICULARLY
low levells or absent of all antibodies total below 100mg/dl
western blot to show if the Btk protein is expressed
women with an XLA patient in their family should seek what ?
genetic counselling
when having x linked hypogammaglobulinemia what should be considered
avoid LIVE ATTENUTAED VACCINES scuh as :
polio vaccine should not be administered - for there can be paralyse or fatal CNSinfecions
messes , mumps and rubella
no allergic reactions since no IgE is made
they do not have EBV because no b cells
how can we distinguish from x lined agammaglobulinemia and transient hypogammaglobulineiam
natural antibodies to a and b red blood cell and antigens through immunisation is very low in xla whereas normal in transient hypogammaglobulinemia
and normal immunisation action
XLA patienta are more susceptible to ?
septic arthritis
the genes for many immunodeficiency are located on which chromosome ?
the x chromosome
which is the most common immunodeficiency ?
Iga immunodeficiency
who are more susceptible to IgA deficiency
predisposition to caucasians
in pedigree of CVID in the family
associated with autoimmune disorders
more common in diabetes type 1
celiac disease associated
what is the clinical presentation of IgA deficiency ?
type 3 hypersensitivities - immune complex diseases
IgA antibody that protects against infections of the mucous membranes lining the mouth, airways, and digestive tract
Most people remain healthy never diagnosed
sinopulmonary pyogenic infections and gastrointestinal infections esp - giardiasis
can cause non haemolytic transfuse reactions - because serum antibodies TO IgA NOTED
why are individuals with deficiency to IgA susceptible to pyogenic infections ?
20 percent of the IgA deficient people also have deficicny for IgG2 andG4 subclass deficiency = resulting in recurrent pyogenic infections
what is the pathophysiology of IgA deficiency ?
NORMLAMOUNT OF B CELLS
change in terminal differentiation of B cells
how do we diagnose IgA deficicny ?
diagnosis cannot be made until 4 years of age when the iga levels should come to mature level
less than 5 mg/dl or absence of IgA serum conc and other antibodies are normal
what is the treatment for x linked agammaglobulinemia ?
blood pool extracted from thousand of blood donors of intravenous infusion of immunoglobulin IVIg - esp IgG every week for life
attempt at IgG level of 800mg/kg
its not a cure but increase the quality of life and life span generating passive immunity
prophylactic antibiotics - local preferred
IgA immunodeficiency has the chance to evolving into ?
CVID
what is the treatment of IgA deficiency ?
identification of co morbid condition
prophylactic antibiotics
what can IgA complicate the diagnosis of ?
celiac disease - for diagnosis increase in IgA is used
what is the pathophysiology of High IgM deficiency ?
patients who are IgG and IgA deficiency and produce large amount go IgM (more than 200mg/dl)
5 types
type 1 - X LINKED - mainly affects boys
t cells cannot tell b cells to switch classes
caused by mutations in the gene that encodes the CD40 ligand which is expressed on activated T-helper
Boys with this syndrome have very low serum concentrations of IgG and IgA, with a usually normal or sometimes elevated concentration of polyclonal IgM;
impaired dull maturation of dendritic cells
IL-2 production of dendritic cells and macrophages impairment
type 2 - autosomal recessive - b cells can’t do genetic recombination to change into heavy chain production cannot switch . intrinsic defect.
type 3 - b cells cannot receive the signal from t cells to switch classes (t cells release the cd40)
4 )
5)
High IgM IMMUNODEFICICNY clinically present with
type 1 = significant susceptibility to opportunistic infections
boys symptomatic in 1st or 2nd year of life
may or may not have small tonsils;
usually have no palpable lymph nodes;
often have profound neutropenia
recurrent pyogenic infections = otitis media , sinusius , pneumonia , tonsilitis
MARKED pneumocystitis pneumonia !(pneumocystis jiroveci) - common in infants with hyper IgM - many CD40 disturbance is diagnosed after having pneumocystis pneumonia
verruca vulgaris lesions
cryptosporidum enteritis = failure to thrive , weight loss and diarrhea (only detectable by PCR)
oppurtunitistic = cryptosporadium found in billary tree = disturbed liver function nd scelrosing cholangitis = cirrhosisi = risk of cholangiocarinoma
LIVER DISESE IS VERY COMMON
hepatitis
chronic diarrhea
type 3 is identical
type 2 lymphoid hyperplasia are generally older at age at onset, do not have susceptibility to P. jiroveci pneumonia less likely to have neutropenia
Tendency, however, to develop autoimmune and inflammatory disorders, including diabetes mellitus, polyarthritis, autoimmune hepatitis, hemolytic anemia, immune thrombocytopenia, Crohn disease, and chronic uveitis.
what is the problem in high IgM ?
from IgM autoantibodies to neutrophils , platelets , and other blood cells and tissue leading to autoimmunity
which tissue are most susceptible in autoimmunity from high IgM
GI tract - risk for lymphoproliferatve diseases
how to diagnose hyper IgM?
antibody serology = gG, IgA, and IgE are very low
high igm
Type 1
LYMPHNODE HISTOLOGY
= ABORTIVE GERMINAL CENTRE FORMATION WITH SEVERE depletion and phenotypic abnomraltitis in follicular dendritic cells
normal amount of B cells - decreased CD27 memory b cells
decreased antigen specific T cell function even if there is normal amount of T cells.
flow cytometry expression of CD40
type 2
Histologic examination of the enlarged lymph nodes reveals the presence of giant germinal centers filled with highly proliferating B cells
what is the treatment of hyper IgM ? for type 1 and 2
type 1 - allogenic hematopoietic cell transplantation early
cannot be controlled by IgG substitiion however IVIgG is still used to prevent
antimicrobial therapy
granulocyte colony stimulating factor = neutropenia
immunosuppressants = autoimmune diseases
type 2
IVIG, as well as good management of infections with antibiotics
IgG SUBCLASS DEFICIENCY can lead to what complication?
develop CVID
should IVIG be administered to patients with IgG subclass deficiency
no unless they are shown to have a deficiency of antibodies to a broad array of antigens
Common variable immunodeficiency (CVID) is an immune disorder characterized by recurrent infections and low antibody levels, specifically in
extremely low IgG, IgM and IgA.
Individuals with CVID lead to agammaglobulinemia when?
second or third decade of life
etiology of CVID?
higher in caucasians / asians and africa americans
not hereditary but associated with MHC HAPLOTYPES hlab8 and hladr3
after ebv sensitisation
clinical presentation of CVID?
Infections mostly affect the respiratory tract (nose, sinuses, bronchi, lungs) and the ears; they can also occur at other sites, such as the eyes, skin and gastrointestinal trac
Bronchiectasis can develop when severe, recurrent pulmonary infections are left untreated.
esp diarrhea - giardia
Patients with CVID often have autoantibody formation
normal-sized or enlarged tonsils = differentiate from xla
and lymph nodes
what are the complicationsof CVID?
autoimmune manifestations, e.g. pernicious anemia, autoimmune haemolytic anemia (AHA), idiopathic thrombocytopenic purpura (ITP), psoriasis, vitiligo, rheumatoid arthritis, achloridiya
malignancies, particularly Non-Hodgkin’s lymphoma, and gastric carcinoma, cell lymphoma
CVID enteropathy are similar to those of celiac disease, but don’t respond to a gluten-free diet. blunting of intestinal villi and inflammation, and is usually accompanied by symptoms such as abdominal cramps, diarrhea, constipation and malabsorption and weight loss. before d rule of infection caused enteropathy esp giardiasis lamblia
lymphocytic infiltration of tissues, which can cause enlargement of lymph nodes (lymphadenopathy), of the spleen (splenomegaly) and of the liver (hepatomegaly), as well as the formation of granulomas. In the lung this is known as Granulomatous–lymphocytic interstitial lung disease.
lymphoid interstitial pneumonia
diagnosis of CVID IS MADE WHEN?
CVID is diagnosed if:
the person presents with a marked decrease of serum IgG levels (<4.5 g/L or <2 standard deviations below the age-adjusted norms) and a marked decrease below the lower limit of normal for age in at least one of the isotypes IgM or IgA
the person is four years of age or older
the person lacks antibody immune response to protein antigens or immunization.
serum immunoglobulin levels in people with CVID vary greatly. Generally, people can be grouped as follows?
no immunoglobulin production, immunoglobulin (Ig) M production only, or both normal IgM and IgG production
other than immunoglobulins what else varies in CVID paints ?
B cell numbers are also highly variable. 12% of people have no detectable B cells, 12% have reduced B cells, and 54% are within the normal range
In general, people with CVID display higher frequencies of which b cell ?
naive b cell )b cell not exposed to antigen )
lower frequency of cars switched memory b cells , memory b cell ,
CVID Affected individuals typically present with low frequencies of what associated to t cell
CD4+, a T-cell marker,
and decreased circulation of regulatory T cells and iNKT cell
how many types of CVID is there
6 types
what is the treatment of CVID ?
Ig replacement therapy - via intravenous , subcutaneous or Im (not used anymore) every 3/4 weeks
immune suppressants for autoimmune symptoms such as corticosteroids
antibtics to fight of infections