IVIG

Therapeutic Roles 

Immunodeficiency

• antibodies that can neutralize bacterial toxins or  
• opsonins that can promote phagocytosis
• eliminate complement activating circulating immune complexes

• neutralize autoantibodies                                
• downregulate B and T cell function                                                                                                                             
• cytokine regulation
• Fc receptor blockade 
• eliminate complement activating circulating immune complexes

IVIG

Specific Immunologic Effects

Adaptive Immunity

• Tcell effects:  decrease T cell prolif and activation; expands T reg cells, increases suppressive fxn of T cells (impt in autoimmune processes)
• Regulates B cells, maybe mast cells and basos via inhibitory Fc gRIIB (inhibitory G receptor)impt in antibody mediated autoimmune disease

• NK cell fxn modulation
• Monocyte fxn modulation
• Downreg pro inflamm cytokines, and trafficing via adhesions molecules

• Highly purified (>95%) serum IgG
• Derived from avg of 10,000 donors/lot
• Monomeric (if polymeric more adverse reactions w aggregation)
• Small amounts IgM and IgA-varies w product
• One gram IVIG contains 4X 10¹⁸ molecules of Ab, >10⁷ spsecificities to a broad range of bacterial and viral pathogens
• May be stablized w sugars or amino acids, varies by product.  Moving towards amino acids to decr adverse events

• IM until 1981
• IV once aggregation was managed
• SubQ
• Oral (in persistent rotovirus... off label)

Rate related &/or to minor contaminants:

• Fever, chills, flushing
• Tachycardia, palpitiations, chest tightness/pain
• Anxiety, nausea, abdominal pain
• Dyspnea, back pain, arthralgias, myalgias, urticaria
• Hypotension, shock

• Activation of complement by Ig aggregates
• Ag-Ab complexes esp heavy antigenic loads or if heated to mix (don't!)
• Vasoactive proteins present as contaminants

IVIG

Adverse Reactions 2

• Most are mild, reversible
• Incidence 5-10%
• Can occur 6-24 hours later
• More common with older formulations, less frequent with 4th/5th generation products
• Most commonly in newly diagnosed pts  &/or with chronic infection and bacterial or inflammatory products  present in tissues/plasma which result in IC disease

IVIG 

Adverse Reactions 3

• Aseptic meningitis: frequently w high dose (1-2gm/kg ie in immunomodulatory conditions)- migraine history may be predisposing, may consider changing brands or decreasing rate of infusion
• Renal dysfunction: esp w sucrose-containing products: Acute tubular necrosis                          Risk factors: prexisting DM, Renal insuff, age and dehydration
• Thromboembolic events: ? increased blood viscosity, more frequent with lyophilized products and in pre existing autoimmune disease, large doses, rapid infusion rates.  Most products now liquid
• Maltose-containin products:  false readings w glc monitorin

• Pause IVIG
• Acetominophen
• NSAIDS
• Anti-histamines
• ? Steroids
• Restart IVIG at latest rate not causing reaction

• No IV access/port needed
• Eliminates need to monitor trough levels
• Less systemic side effects than IV
• Easy home therapy

• Frequent dosing due to volume limitations at any one site   q 5-7 days
• Local infusion site reactions
• Depends on patient reliability
• Needs a working pump

IVIG

Adverse Reactions to IgA

• Anaphylactic (IgE vs IgA in IgA naive pts)vs anaphylactoid.  
• No longer able to assay for IgE to IgA,  ? ST but be careful of irritant concentrations
• Serum-sickness like reactions due to IgG towards IgA -Uncommon
• Newer IVIG preps with very low IgA levels

• Mid 90's:  change in screening assay for HepC found presence and transmitted to ID pts
• Changed donor screening, PCR testing (improves detection during 'window period' when serology neg)
• Inventory management:  plasma held until donor is retested in several months before release 
• Viral inactivation: solvent/detergents, nanofiltration

• Late 90's: donor came down w CJD so lot was held and marked shortage/concern re transmission via plasma products
• No retrospective basis for transmission by blood products (+ for tissue transmissions)
• 2001: new prion dz in UK (new variant CJD that CAN be transmitted by serum) therefore screening and limitations for donors with hx travel outside the US an improved, extra nanofiltration step in processing

IVIG 

FDA Approved Indications for Usage

• PID:  Bcell ID, Ab deficiencies
• ITP
• Kawaski
• B cell CLL w recurrent bacterial infections
• Pediatric HIV
• BMT for GVH, infections, interstitial CMV pneumonia
• Chronic inflammatory polyneuropathy (new)

IVIG 

Efficacy in PID

• Standard of care: no other acceptable alternative exists
• Early dectection and tx prevents organ damag and development of secondary inflammatory disorders
• Reduces febrile episodes, # of infections, missed school and work days

IVIG

NOT indicated for:

• Seletive IgA deficiency
• Transient hypogamm of infancy
• Hypogamm due to protein losing states
• IgG subclass deficiency unless antibody deficiency/functional defect demonstrated

IVIG 

DOSAGE

• 400 mg/kg to achieve trough>500mg/dl (trough levels gradually increase over first 9 mos of therapy)
• For every 100mg/kg IVIG, peak serum IgG increases by 200-300mg/dl and trough levels by 100mg/dl
• Varies w pt's tissue distribution and catabolism
• Must be adjusted in pregnant women who increase their volume of distribution: fetus will not recieve transplacental IgG during 3rd trimester

• Trough levels at which infection control is achieved may be higher or lower than 'standard' suggested levels (ie >750 mg/dl may be more effective
• May be more achievable with Sub Q

IVIG

Off label use

see list p1277

• many grey areas
• autoimmune neurologic processes and autoimmune disease have reasonal basis
• new:  ?Alzheimer's  trials in progress