Lecture 3: Immunodeficiencies & Monoclonal Antibody Technology

Week 2 - Dr. Thomas - 641

Immunodeficiencies: Innate Immune System

Immunodeficiencies: Adaptive Immune

System

Congenital Immunodeficiencies: Lymphocyte

Maturation

Congenital Immunodeficiencies: Defects in Lymphocyte Maturation

• SCID require bone marrow transplantation

• Common gamma chain - lack of IL-7

Congenital Immunodeficiency Due to Defects in Lymphocyte Function

• AID - activation induced deaminase

• Th1 cell + CD40L - activates macrophages and signals to the B cell, which activates AID

  • understand what AIDs function is

    • activation-induced deaminase is induced in B cells and helps mediate class switching recombination and somatic hypermutation after CD40 binds CD40L

  • understand CD40L mutation, this is more severe

    • No class switching, B cells stay stuck in making IgM

    • Poor macrophage activation = opportunistic infections

• CD40 is rare and is X-linked, so primarily in males

Acquired (Secondary) Immunodeficiencies

HIV infection causes immunodeficiency by attacking host immune cells

• when host is first exposed, virus dragged to lymph notes, experience a viremia

• virus, being a retro-virus, starts to rotate and mutates, making it harder to eradicate - sits in lymph nodes and avoids immune detection

  • retro-virus is an RNA virus that replicates by converting its RNA into DNA inside the host cell. The defining feature is the enzyme reverse transcriptase which performs RNA → DNA

• "holy grail" to treating HIV is to figure out how to get the cytotoxic T cell to kill the virus, and the to kill the virus-infected cells - only way to eradicate the virus

• Ppl infected w HIV have to have CD4 counts to ensure those numbers are no dropping even more; CD4 drop is hallmark feature of HIV = kills CD4+ T cells

Anti-Viral Treatment Targets Strategic Points of Viral Life Cycle

Note where these agents target in the viral life cycle - these attempt to control the replication of the virus … by turning on CTLs when CD4+ helper cells are lost

• reverse transcriptase inhibitors

• integrase inhibitors

• protease inhibitors

Antibody repertoire produced by recombination in developing B cell

• The immune system generates enormous antibody diversity before exposure to infection so it can potentially recognize almost any antigen it encounters.

Monoclonal antibody production via hybridoma

• take a mouse and bias its immune system with a chemical structure injection, isolate B cell from the mouse, immortalize the B cell by fusing it with a cancer cell - have an infinite source of B cells and store them away until needed

  • generate B cell population - recall its function/significance

  • then screen the mice for the one with the best characteristics that reacts to the antigen, which in this case is a drug molecule

• Labor Intensive

  • Slow- inefficient (fusion % low)

  • Antigen Limitations (Must be immunogenic/nontoxic)

• Antibodies from Mice may induce Hypersensitivity Reactions (e.g., Type III Immune Complex Rx)

• Need to “humanize” Antibody or use Transgenic Mouse with “Human” Immune system

Limitations

• If you want to generate an antibody to the antigen/target, know the constraints of the antigen:

  • the antigen has to stimulate an immune response

  • antigen cannot be toxic, has to surpass minimal constraints

Companion Technologies for Monoclonal Antibody Production

• Generation of a “Naïve” Human Antibody Library

• Employs Phage Display method for screening Antibody binding

• Clone Antibody Genes in Expression System, e.g., CHO cells

• isolate B cells

  • presents population

• understand how this first step leads to critical gene? modifications

Biosimilars

• Medicine that is very similar to an existing biologics drug, with no meaningful differences in safety, effectiveness, or quality