Components of Immune System MCQs

Ans. is 'a' i.e., Peroxidase Neutrophils and monocytes contain a peroxidase (myeloperoxidase), that has been implicated in antiparasitic activity. However, monocytes lose this enzyme when they mature into macrophages. Eosinophils also contain peroxidase that differs from myeloperoxidase of neutrophils. However, like myeloperoxidase, eosinophil peroxidase combines with H20, and a halide to form an antiparasite system. Parasite Egg size 1) Fasciola gigantica 190 X 100 m 2) Echinostoma iliocanum 100 X 70 m 3) Gastrodiscoides hominis 150 X 70-100 m 4) Opisthorcis viverni <30 X 15 m

There are two types of adaptive immunity. Humoral immunity is mediated by soluble proteins called antibodies that are produced by B lymphocytes(also called B cells). Cell-mediated(or cellular) immunity is mediated by T lymphocytes(also called T cells). Humoral immunity is the aspect of immunity that is mediated by macromolecules - including secreted antibodies, complement proteins and certain antimicrobial peptides - located in extracellular fluids. Humoral immunity is named so because it involves substances found in the humors or body fluids. Reference: Robbins and Cotran Pathologic Basis of Diseases, 10 th ed, Pg: 124.

The human major histocompatibility complex(MHC) commonly called as human leukocyte antigen(HLA) complex is a 4 megabase region on chromosome 6p. The major histocompatibility complex(mhc) is a group of genes that encode proteins on the cell surface that have an important role in immune response. Their main role is in antigen presentation where mhc molecules display peptide fragments for recognition by appropriate t-cells. Reference: Harrison, 17 th ed, Pg: 2045

ANTIGEN PRESENTING CELLS ARE B CELLS, DENDRITIC CELLS AND MACROPHAGES Dendritic cells(DCs) are the most important antigen presenting cells for initiating T-cell responses against protein antigens. A special type of immune cell that is found in tissues, such as the skin and boosts immune responses by showing antigens on its surface to other cells of the immune system. A dendritic cell is a type of phagocyte and a type of antigen-presenting cell(APC). Reference: Robbins and Cotran Pathologic Basis of Diseases, 10 th ed, Pg: 128.

HIV infects cells by using the CD4 molecule as a receptor and various chemokine receptors as coreceptors. Binding of HIV gp120 to CD4 is essential for infection and accounts for the tropism of the virus for CD4+T cells and for CD4+monocytes/macrophages and DCs. In molecular biology, CD4 is a glycoprotein that serves as a co-receptor for the T-cell receptor. CD4 is found on the surface of immune cells such as T helper cells, monocytes, macrophages and dendritic cells. Reference: Robbins and Cotran Pathologic Basis of Diseases, 10 th ed, Pg: 175.

The major classes of innate immune receptors are TLRs, NOD-like receptors in the cytosol(NLRs), C-type lectin receptors, RIG-like receptors for viral RNA, named after the founding member RIG-I and cytosolic DNA sensors. Caspases are a family of protease enzymes playing essential roles in programmed cell death. They are named caspases due to their specific cysteine protease activity - a cysteine in its active site nucleophilically attacks and cleaves a target protein only after an aspartic acid residue. Reference: Robbins and Cotran Pathologic Basis of Diseases, 10 th ed, Pg: 122.

True, because of its morphology False, T lymphocytes need thymus for development True, CD16 is FcR of IgG true, NK cells kill viruses & tumor infected cells Reference: Robbins & Cotran Pathologic Basis of Diseases 10 th edition, Chapter - 6, pg 192

Immunofluorescence studies reveal the characteristic strong linear staining with IgG and C3 along the GBM in anti-GBM antibody-mediated disease, a granular pattern of glomerular staining in immune complex-mediated GN, while in pauci-immune GN the stains are negative. Electron microscopy shows electron dense immune complex deposits within the glomeruli in immune complex-mediated GN, but not in biopsies from those with anti-GBM and pauci-immune crescentic GN. Reference : Robbins Basic Pathology, 10 th edition, Page- 563