(2) Chapter 19: Disorders of Immune System

What are rheumatoid factors?

Rheumatoid factors are IgM-IgG immune complexes found in about 70% of rheumatoid arthritis patients.

What causes rheumatoid arthritis?

IgG, IgM, and complement immune complexes (possibly associated with streptococcal antigens) deposit in joints, activate complement, and destroy cartilage and bone, beginning with the small joints of the hands and feet.

What causes insulin-dependent diabetes mellitus (Type 1 diabetes) according to the lecture?

Cytotoxic T cells destroy the insulin-producing pancreatic cells, preventing insulin production and causing malnutrition unless insulin is replaced.

What causes multiple sclerosis (MS)?

Cytotoxic T cells attack the myelin sheath surrounding nerves, slowing nerve impulse transmission and causing progressive muscle weakness, paralysis, and sometimes blindness. Macrophages and antibodies also contribute to inflammation.

Compare Graves disease and Hashimoto's thyroiditis.

Graves disease causes hyperthyroidism because antibodies stimulate TSH receptors. Hashimoto's thyroiditis causes hypothyroidism because cytotoxic T cells destroy the thyroid gland.

What are common signs of Hashimoto's thyroiditis?

Hypothyroidism, decreased metabolic rate, decreased heart rate, hair loss, feeling cold, and in severe cases removal of the thyroid gland followed by lifelong thyroid hormone replacement.

What causes psoriasis?

Cytotoxic T cells attack skin cells and release cytokines that stimulate keratinocyte growth, producing thick red, white, scaly skin patches, commonly on the elbows.

What percentage of people with psoriasis develop psoriatic arthritis?

About 25%.

How are psoriasis and rheumatoid arthritis commonly treated?

Corticosteroids are commonly used as anti-inflammatory drugs.

What is immunological surveillance?

The immune system continuously searches for and destroys abnormal cells, including cancer cells.

Which immune cells participate in immunological surveillance against cancer?

Natural killer (NK) cells, cytotoxic T cells, macrophages, and dendritic cells.

Why can cancer develop despite the immune system?

Cancer cells multiply rapidly and may lack recognizable antigenic epitopes, allowing them to escape immune destruction.

How did Dr. Coley's bacterial endotoxins help treat cancer?

Bacterial endotoxins interfered with tumor blood supply (vascularization), reducing cancer growth.

What are prophylactic cancer vaccines?

Vaccines designed to prevent certain cancers before they develop rather than treat existing cancer.

What are HLA (human leukocyte antigens)?

HLA are the human major histocompatibility complex (MHC) antigens that distinguish self from non-self and are matched before transplantation.

Why is HLA typing important before transplantation?

HLA matching reduces the likelihood of transplant rejection in addition to matching ABO and Rh blood types.

What diseases did the professor associate with certain HLA types?

Multiple sclerosis, rheumatic fever, Addison's disease, Graves disease, and Hodgkin lymphoma have increased risk with certain HLA types.

What are the major types of grafts?

Autograft (same person), isograft (identical twin), allograft (different person of same species), and xenograft/xenotransplant (different species).

Which tissues are considered immunologically privileged?

Cornea, brain, and pig heart valve transplants have relatively lower rejection rates.

What is graft-versus-host (GVH) disease?

A complication of hematopoietic stem cell (bone marrow) transplantation in which donor immune cells attack the recipient.

Which cells primarily reject transplanted tissues?

Cytotoxic T cells.

Know the immunosuppressive drugs mentioned in lecture.

Cyclosporine, Tacrolimus, Basiliximab, Sirolimus, and Mycophenolate suppress the immune system to reduce transplant rejection.

What are the disadvantages of immunosuppressive drugs?

They must often be taken for life and increase the risk of infections and cancer because the immune system is suppressed.