Tuesday, 2 June 2020

Cellular immunity& COVID-19 infection


ABC of Cellular immunity: Q,1: What are primary  lymphoid organs in human body??    : Ans: These are Bone marrow& thymus.  Q.2:-What are secondary Lymphoid organs: These are 1) Lymph nodes, 2) Tonsils 3) Spleen are termed as Secondary lymphoid organs.  Of two  kinds of immunity i.e. humoral and cellular the cellular immunity is mediated by T lymphocytes, which are also called T cells. Their name refers to the organ from which they're produced: If from  the thymus then such spl lymphocytes are called T cells.: This type of cellular  immunity promotes the destruction of microbes residing in phagocytes, or the killing of infected cells to eliminate reservoirs of infection.
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Q.3: What are the functions of Secondary lymphoid organs?? Ans;- These secondary lymphoid organs filter many circulating microorganisms and antigens.   Secondary lymphoid organs contain good amount of T cells and B cells. If too much antigens /microorganism are being filtered, as happens in acute infections , then in secondary  Lymphoid system then such organs synthesize large amount of T & B cells population. . This type of  cellular immunity promotes the destruction of microbes residing in phagocytes, or the killing of infected cells to eliminate reservoirs of infection 
Q. 4: Where synthesized??  Ans:-T cells and B cells are primarily synthesized in bone marrow but later settle at different parts of body lymphoid system. As young T cells arrive at thymus gland there is some activation young still immature T cells with increased power to fight with invading organisms. These changes in thymus gland are termed s “Thymic education”.
Q. 5: Why the name T cells??  Ans:- The name T cells as  is acquired from the fact that T cells  get acquisition of  functional  maturity at thymus.  . The large amount of cytotoxic T cells immediately kills the bacteria / invading foreign antigens. B Cells also can destroy foreign antigens.
Q. 6: Are T , B cells are a kind of lymphocytes?? Ans: Very true. T cell, (also called T lymphocyte) are one kind of leukocyte that is an essential part of the immune system.

Q. 7: What the  different kinds of lymphocytes?? Ans:-In fact there are two primary types of lymphocytes—. T cells  &  cells . B cells being the second type. The peculiarity of  B cells of lymphocytes is to ascertain  the specificity of immune response to antigens (foreign substances) in the body. They quickly respond to foreign cells to fight infection, battle a virus or defend the body against bacteria.
Q.8: Is it congenitally derived or   acquired immunity? Ans; These cells are dormant at  birth and  with passage of time as a child grows such T & B cells acquire functional competency  called adaptive immunity.
Q. 9:-What are CD4 cells (also known as CD4+ T cells)?? Ans: Such CD4 cells    are white blood cells that fight infection and this CD 4 count is specifically used in HIV infection.  As HIV infection progresses, the number of these cells declines. When the CD4 count drops below 200, a person is diagnosed with AIDS. normal range for CD4 cells is about 500-1,500 .  Usually, the CD4 cell count increases when the HIV virus is controlled with effective HIV treatment. The higher is  CD4 count, the better. Healthy T cell count should be between 500 and 1,600 T cells per cubic millimeter of blood (cells/mm3) Q,. 10:  When lymphocyte counts go up?? Lymphocyte counts above the normal range can be a harmless and temporary situation due to the body's normal response to an infection or inflammatory condition. But a high level of lymphocytes can also be a sign of lymphocytosis, which is a more serious condition.

Q.11:- When we will be worried about less CD4 cell count?? . CD4 T cell depleted to the cell count of less than 200cell/μL in blood during AIDS. In such a situation body loses control over fighting against organisms and thereby allows various pathogens to escape T cell recognition. The organism as it escapes T cells will circulate in  blood freely à  thus allowing opportunistic infections to grow and flourish.  But in normal conditions with adequate CD  4 count the very entry of organisms  elicit a helper T cell response to bypass the immune system.

Q 12. What are the types of T cells? Ans:-:           There are 3 main types of T cells: cytotoxic, helper, and regulatory. Each of them has a different role in the immune response. Cytotoxic T cells (Tc cells) have a co-receptor called CD8 on their cell surface.
Q. 12; how we can boost up our immunity and thereby lead a healthy life?? Here are 9 tips to strengthen ones immunity naturally.
1.        Get enough sleep. Sleep and immunity are closely tied. ...
2.        Eat more whole plant foods. ...
3.        Eat more healthy fats. ...
4.        Eat more fermented foods or take a probiotic supplement. ...
5.        Limit added sugars. ...
6.        Engage in moderate exercise. ...
7.        Stay hydrated. ...
8.        Manage your stress levels.
Q. 13: If immune mechanism fails then what happens?? Ans;-During the shut-down of the immune response activated lymphocytes are removed by two mechanisms. T cells that are re-stimulated during the end of the immune response die by “activation-induced cell death (AICD)” , whereas activated lymphocytes which are not re-stimulated die by activated cell autonomous death (ACAD).

Q. 14: What do we mean by Viral load in case of HIV?? Ans:-The results of a viral load test are described as the number of copies of HIV RNA in a millilitre of blood. But physician will normally try to keep viral load at a low number. For example, a viral load of 10,000 would be considered low; 100,000 would be considered high.
Q.15:- What is the normal lymphocyte range in adults?? Ans: The normal lymphocyte range in adults is between 1,000 and 4,800 lymphocytes in 1 microliter (µL) of blood. In children, however the normal range is between 3,000 and 9,500 lymphocytes in 1 µL of blood. Unusually high or low lymphocyte counts can be a sign of disease.
 Q. 16: What is iterleukin-7 ?? There are several kinds of interlekin-7 all of which can control the immune system of body. Such interleukins are derived from bone marrow and thymic gland. Of them one which “fibroblast derived IL-7”- is synthesized at bone marrow & thymic gland. Therefore administration of such fibroblast derived cytokine can destroy or at least resist CONVID-19.

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