Immunology and Immune Response Notes

Primary Immune Response

Definition: The primary immune response is the body's initial reaction to a pathogen (or antigen).
Process:
- First exposure involves a lag phase (2-3 days or more) where the body learns to recognize the pathogen.
- Innate immune system attempts to stop the pathogen before the adaptive immune system is activated.
Lag Phase: The body takes time to process the pathogen, and initial antibody response is low but gradually increases as the immune response strengthens.

Types of Antibodies:
- IgM: First antibody produced during a primary infection; present initially in small amounts.
- IgG: Present during primary infections in smaller quantities but dominates in secondary infections.
Maternal Transfer:
- IgG can cross the placenta to provide immunity to the fetus.
- IgM attacks during the initial exposure, while IgG becomes prominent in case of subsequent infections.
Electrophoresis: A technique used to separate antibodies based on molecular weight to determine their levels in blood.

Shorter lag phase due to memory B cells from previous infections.
Higher levels of IgG produced during secondary infections as the body rapidly mobilizes an immune response due to memory:
- Memory B Cells: Specialized cells that improve and expedite the antibody response during re-exposure to the same pathogen.

Active Immunity: Developed through exposure to pathogens or through vaccination.
Passive Immunity: Transfer of antibodies from one individual to another (e.g., maternal antibodies), which provides temporary protection.

Definition: Refers to individuals with weakened immune systems, making them more susceptible to infections.
Treatment: They may receive pooled IgG from multiple donors to boost immunity against various pathogens.

Explained as the phenomenon where a significant portion of a population becomes immune (through vaccination or previous infection), indirectly protecting those who are not immune.

Definition: Preparations that introduce antigens (epitopes) to stimulate an immune response without causing disease.
Types of Vaccines:
- Attenuated Vaccines: Weakened live pathogens; elicit strong immune responses and sometimes require fewer doses.
- Potential risks for immunocompromised individuals due to the risk of reversion to virulent forms.
- Inactivated Vaccines: Contain killed pathogens; induce weaker immune responses and often require multiple boosters.

Definition: Utilizes the immune system to treat diseases, particularly cancer.
Mechanisms:
- Enhances immune response by targeting specific immune cells (e.g., T cells).
- Can involve using cytokines like Interleukin-2 (IL-2) to boost T cell activity.
- Uses Checkpoint Inhibitors to block cancer cells from evading immune detection.
Risks: Can harm normal cells and suppressive responses may be necessary in autoimmune diseases where the immune system attacks the body itself.

Definition: Tests using antigen-antibody interactions to detect diseases.
Types:
- Qualitative Tests: Indicate presence or absence of antigens/antibodies (e.g., pregnancy tests).
- Quantitative Tests: Measure concentrations of antibodies (e.g., titer tests).

Definition: Branch of immunology focused on blood serum and its antibodies to diagnose or monitor diseases.
Tests:
- Seropositive: Indicates the presence of antibodies.
- Seronegative: Indicates absence of antibodies.
- Seroconversion: The process of developing antibodies in response to an infection, signifying an active infection phase.

Importance of understanding immunological testing and categorizing vaccine types, also distinguishing between immunotherapy mechanisms and their applications in clinical practice.