Microreview59(Nonspecific Immunity)

Front 1

What are the most important nonspecific first line defenses?

Back 1

Interferons and natural killer(NK) cells.

Front 2

How do interferons work?

Back 2

They inhibit various stages of viral replication by inducing specific antiviral proteins that cleave viral mRNA, suppress protein synthesis, and increase expression of MCH molecules.

Front 3

Do interferons act intracellularly?

Back 3

No. They bind to receptors on the cell membrane to initiate production of the antiviral proteins.

Front 4

What are some important implications of this mechanism?

Back 4

First, interferons generate a nonspecific antiviral response that is only active in virally infected cells.
Second, the antiviral proteins specifically clrave viral mRNA but may suppress normal cell protein synthesis.
Third, interferons cannot act on viruses in the extracellular environment.

Front 5

What are the types of interferons?

Back 5

1. Alpha interferon and beta interferon are important in antiviral responses, stimulation of NK cells and macrophages, and play a role in tumor suppression.
Gamma interferon has weaker antiviral and antitumor effects but serves to enhance the response to alpha and beta interferons.

Front 6

What are some examples of interferon treatment?

Back 6

Interferons can be used to treat chronic viral infections such as hepatitis C or chronic hepatitis B.
Certain cancers are also susceptible to interferon treatment(Kaposi's sarcoma and hair cell leukemia).

Front 7

NK cells are lymphocytes. TRUE/FALSE

Back 7

TRUE.

Front 8

How do NK cells work?

Back 8

NK cells cause apoptosis in cells without major histocompatibility complex(MHC) class 1 molecules.
Viral infected cells or tumor cells often suppress MHC class 1 molecules in an attempt to evade the immune system.