Question

Respond to the following:

An acquired immune response necessitates exposure to an antigen. This initial exposure does not always elicit a leukocyte attack but does program central memory and effector memory T-cell. The innate system is responsible for triggering an adaptive response; the reduction of antigens terminates the immune response. As the infection is eliminated, the quantity of antigens begins to decline. This creates competition between lymphocytes and reduction of new lymphocyte differentiation. Expression of inhibitory signals like CTLA-4, PD-1, and KLRG-1 also occur, along with a reduction in cellular ATP. The cells involved in the adaptive immune response that are not wasted or die, become new memory cells. For some pathogens, innate or humoral immunity is insufficient for defense. This is the case with Bordetella pertussis, which requires a strong T-cell response, to provide immunity. B. pertussis causes whooping cough which can be lethal is allowed to progress, or reinfection occurs. An innate response is initiated and last about 7 days, then a short latent period, followed by acquired response around day 10. The acquired response last until the infection is cleared. The infection by B. pertussis produces a response by Th1, Th2 and Th17 cells. The antigens on B. pertussis, activate signal chains of TNF-α, IFN-γ, IL-5 and IL-13 cytokines (2). T-cell antibodies respond to Filamentous hemagglutinin (FHA), pertussis toxin (PT) and pertactin (PRN) from the B. pertussis bacteria or as components of a vaccine. Vaccines that contain all three components have a higher success rate of immunization. Some vaccines contain B. pertussis fimbriae (FIM) as an antigen. Acquired immune response to B. pertussis is primarily from CCR7+CD45RA−T and CCR7+CD45RA− cells during early childhood (2). A difficulty in illuminating the respiratory track of B. pertussis arises from a type III secretion system (2). Bacterial mechanism serves to produces an anti-inflammatory state in the host leading bacterial proliferation. This protein that the bacteria scan inject directly into the cytosol of tissue cells or most commonly responding leukocytes. It is thought that type III secretion systems disrupt the differing leukocytes ability to attach, T-cell recruitment and cytotoxicity (1). The toxicity and lethality of B. pertussis, arises from the potential to overwhelmed the immune system with type III secretion systems injected cells. It is also thought that B. pertussis immunity is not lifelong and depends on the type of exposure. B. pertussis is vaccinated for children and adults withe the dTap vaccine. It is recommended to be given at 2,4,6,15 months, 4 and 12 years. Pregnant women and healthcare workers are recommended to receive additional vaccinations as well as individuals over 65(3). Natural exposure to B. pertussis elevates the T-cell response more efficiently than synthetic boosters.

Answer 1

Immunity is defined as the state of being g immune from or being susceptible to a particular disease. Or in simple​ words, it is the natural or acquired resistance to the pathology or antigen or any microorganisms of the body. It is the ability to protect the body from viruses, bacteria, toxic substances etc which enter our body.

Now, immunity can be of two types:

1. Innate

2. Acquired

Innate imunity is inherited by tthe organism from the parents and protects it from birthday throughout the life.

For example, human beings have resistance to a disease called distemper which is caused by dogs. So it's the body resistance towards the toxicity which protects us.

But, As it's name suggests it lacks specific responses to specefic Invaders. Innate immunity has it's own specific barriers through which it prevents the entry of bacteria and viruses. These barriers are as follows:

A) physical barriers :- these are mechanical to many microbial pathogens. These barriers include skin and mucous membrane.

B) Physiological barriers :- well, as you know that skin and mucous membrane secretes certain chemicals which dispose off the pathogens from the body. Similarly, the body temperature, body pH and many other things are there which helps in controlling the growth of pathogens inside the body. For example, acids of the stomach kills most ingested organisms, bile does not allow growth of microorganisms, even the cerumen also known as ear wax helps as a barrier by trapping the dust particles and killing bacteria and also repels insects.

C) cellular barriers :- there are certain white blood cells also known as leukocytes, macrophages, natural killer cells, antimicrobial substance, etc.

(i) certain leukocytes- neutrophils and monocytes.

PMNL neutrophils as they have multilobed nucleus they are normally called polymorphonuclear leukocytes. Although they are short lived but are highly motile killers.

(ii) Macrophages- they are highly lived and are highly motile phagocytic.

(iiii) Natural killer cells

(iv) complement

(v) inflammation

(vi) fever

D) Cytokinin barriers :- Cytokinines are low molecular weight proteins that stimulate or inhibit the differentiation process or function of the immune cells. They​ are involved in the cell to cell communication. Interleukins produced by leukocytes is a common example of Cytokinines. Interferons protect against viral infections.

Acquired immunity

The immunity that individual acquires after birth is called acquired or specific immunity. It is mediated by antibodies or lymphocytes that can make the antigen harmless. The memory cells from by B cells and T cells are the actual base of acquired immunity.

Acquired immunity is mediated by the following-

1. Antibody mediated

2. Cell mediated

Antibody mediated :- it consists of proteins produced in the body in response to antigen that circulates in the body fluids like blood plasma and lymph. T lymphocytes do not secretes antibody themselves but help B lymphocytes produce them.

Cell - mediated is the tytype of immunity which is mediated by different types of lymphocytes. Mostly there are T cells which plays a major role. There are various types of T cells such as helper T cells, Cytotoxic cells or Killer cells, Memory cells, suppressor cells.

Formation of memory cells- some activated B cells do not differentiate into plasma cells but rather remain memory cells. They have a longer life span. The memory cells remain dormant until activated once again by new quantity of same antigen.

Types of acquired immunity

1. Active immunity

2. Passive immunity

Active immunity:- in this person's own cells produce antibodies in response to infection or vaccination​. It is slow and it takes time in the formation of antibodies. It is long lasting and is harmless. Active immunity could be natural or artificial. When a patient recovers from small pox or measles or mumps develops natural immunity. Artificial immunity is the resistance through vaccines.

Passive immunity- when ready made antibodies are directly injected into a person to protect the body against foreign Invaders. Although it provides immediate relief, it is not long lasting and it may create problems. It is also natural or artificial.

Now, in the above statement the reference regarding immume system and it's functioning is true. Recent immunolgical investigation have been carried out for the trials of the acellular pertussis in humans. These studies largely confirmed early investigation in the murine respiratory infection that humoral immunity alone iss not sufficient to confer protection against Bordetella pertussis infection and that T cell immunity is required.

I guess the statement is supported by the reference above.