Question

A 2-year-old boy is sent for immunologic testing because of recurring respiratory infections, including

several bouts of pneumonia. The results show decreased immunoglobulin levels, especially IgG.

Although his white blood cell count was within the normal range, the lymphocyte count was low. Flow

Cytometry (cellular separation based on size and CD markers) was performed to determine if a

particular subset of lymphocytes was low or missing. It was determined that he had a low number of

CD3+ lymphocytes, although the CD19+ lymphocyte population was normal. How can this be

interpreted? In other words explain the roles of the cell populations described, how the decrease or

normal level of each affects the function of the patient’s immune system. How does this support or

relate specifically to the patients recurring bacterial infection? (20 pts)

Answer 1

Ans. Before giving answer of this question first of all i want to discuss what is immunity and why its important for us,

Immunity:- its an ability of body to fight against disease when our body feels it is under attack, it makes special proteins called immunoglobulins /antibodies. These antibodies are made by B cells and plasma cells. They are let loose throughout the body to help kill bacteria, viruses, and other germs. The body makes 4 major types of immunoglobulins.

(A) Immunoglobulin A

   (B) Immunoglobulin G

(C) Immunoglobulin M

(D) Immunoglobulin E

( A). Immunoglobulin A :- Immunoglobulin A (IgA) is an antibody of blood protein who is a part of our immune system IgA iits found in mucous membranes, mainly in the respiratory and digestive tracts. It is also found saliva, tears, and breast milk. IgA deficiency seems to play a part in asthma and allergies.

(B) Immunoglobulin G:- Immunoglobulin G (IgG) is the most common type of antibody. IgG is always present in our body to    prevent infections. Its also ready to multiply and attack when foreign substances get into the body. When you dont have enough, you are more likely to get infections.

(C) Immunoglobulin M:- Immunoglobulin IgM is an antibody of blood who is a part of our immune system responsible for serum associated disease its deficiency result with infections, atopic manifestations, autoimmunity, or malignant conditions, but it may also be asymptomatic. There are no other underlying immunodeficiencies. Serum IgM levels are less than 10–15 mg/dl in infants and children and less than 20–30 mg/dl in adults. Other immunoglobulin levels and T cell immunity are usually normal.

(D) Immunoglobulin E:- Immunoglobulin E is an antibody of blood help in preventing allergic conditions IgE secretion from B lymphocytes cell which defines the allergic state and nearly all asthmatic patients  have higher than normal IgE levels in serum following adjustment for age and sex. This allergic mechanisms may be responsible for the increasing prevalence of asthma.

Lymphocytes:- Lymphocytes are white blood cells that are also one of the body main types of immune cells. They are made in the bone marrow and found in the blood and lymph tissue.There are two categories of lymphocytes known as B lymphocytes and T lymphocytes. These are commonly referred to as B cells and T cells.B cells are proteins produced by the immune system to fight foreign substances known as antigens and T cell help the body kill cancer cells and control the immune response to foreign substances.

(A) CD 3 Lymphocytes :- CD 3 are category of T type lymphocyte cell which provide immunity with association from T cell co- receptor which helps to activate both the cytotoxic T cell and T helper cells. It consists of a protein complex and is composed of four distinct chains lower level of CD3 lymphocytes indicate allergic reaction and other bacterial infection like candidiasis,tetanus toxoid,Candida and allogeneic cell.

(B) CD19 lymphocyte :- CD 19 Lymphocytes is a category of B cells which help in early detection of several disease diagnose cancers that arise from this type of cell - notably B cell lymphomas, acute lymphoblastic leukemia and chronic lymphocytic leukemia. The majority of B cell malignancies express normal to high levels of CD 19 lymphocytes.