Question

1.

The co-stimulatory signal provided by T independent type 2 antigens:

1. B7

2. IL-4

3. mitogen

4. extensive receptor cross-linking

5. CD40L

2.

An inappropriate immune response to harmless antigens or an immune response so strong it causes problems for the host:

1. hypersensitivity

2. immunodeficiency

3. sensitization

4. anergy

5. inflammation

A woman was seen in a rheumatology clinic with stiff painful joints. Other symptoms included fatigue, a low-grade fever, weight loss, and a nonspecific rash on her face and chest. A renal biopsy showed lupus nephritis. What do you think is the cause of the rash?

1. contact dermatitis

2. inflammatory cytokines

3. Arthus response

4. inflammation caused by complement activation

5. inflammation caused by histamine

Answer 1

1. Answer: CD40L

• B- cells may be activated, by direct interactions with TH cells, and are called response to thymus-dependent (TD) antigens, or may be activated without direct contacts with TH cells, by thymus-independent antigens.
• T-independent antigens may be of two types: Ti-1 and Ti-2 antigens.
• Ti-1 antigens have mitogen activity, leading through proliferation of B-cells. They are stimulated through toll-like receptors on B-cells.
• Ti-2 antigens activation is dependent on multivalent receptor crosslinking with Ig.
• The co-stimulation includes CD-40 – CD-40L, which facilitates T cell and B cell interaction.

2. Answer: Hypersensitivity

• Hypersensitivity reactions or allergies: A series of cascaded immune response occurring due to certain effector molecules, leading to deleterious effect on the host tissues. The effect may result in immediate hypersensitivity or delayed-type hypersensitivity.
• Hypersensitive reactions cause symptoms like hay fever, hives, asthma, anaphylactic shock or non-allergic reaction like wheal and flare reaction (also called P-K reaction as per Prausnitz and Kustner).

3. Answer: inflammation caused by complement activation

Autoimmunity: This condition arises, when the body’s defense mechanism, lacks the ability to distinguish between self and non-self-components. The type and symptom of autoimmune disease differs on the type of tissue or part of the body affected.

Some major autoimmune diseases are, Rheumatoid arthritis, Hashimoto’s thyroiditis, systemic lupus erythematous (SLE), auto immune hemolytic anemias.

Autoimmunity may result in sensitized red blood cells, or autoantibodies.

The rash may be due activation of complen=ment system.