Cytology Genetics and Infectious Diseases

Greetings to all, today we going to give Cytology Genetics and Infectious Diseases  PDF to help our daily users. Cytological diagnosis of infectious diseases is as important as the cytodiagnosis of malignancies because the detection of pathogens in cytological specimens is crucially valuable for prompt and appropriate patient treatment. When compared with histological diagnosis, cytology is powerful at catching microbes under Papanicolaou and Giemsa stains. Host response against the transmissible agent can be estimated by the type of surroundings inflammatory cells. Patterns of the inflammatory cellular reactions against extracellular and intracellular pathogens should be acknowledged. Immunocytochemical and molecular techniques can be applied, even when we have only one cytology specimen in hand.

The cell transfer technique is useful to create plural material from one glass slide for immunocytochemistry and other techniques. In the case of transmissible disorders including sexually transmitted diseases, the prompt and appropriate diagnosis will avoid avoidable transmission of infectious agents among people, and eventually contribute to the safety of human society. we have given Cytology Genetics and Infectious Diseases in pdf format for free you can download it from the link which is given at the end of this page

Cytology Genetics and Infectious Diseases PDF

1. Introduction

In the daily practice of the cytological diagnosis, cytopathologists tend to focus on the diagnosis of premalignant and malignant diseases. Generally speaking, the cytology practice functions as screening for malignancy. However, the cytodiagnosis of infectious diseases and the identification of pathogens in cytological preparations must not be undervalued. The correct cytodiagnosis of infectious diseases leads patients to prompt and appropriate treatment. Histopathological diagnosis is strong at recognizing host responses against pathogens, while pathogens are more easily identified in the cytology specimen than the histology specimen. When infectious diseases are clinically suspected, it is better for us to perform Giemsa staining in addition to routine Papanicolaou staining.

2. Defense mechanisms against infection

Defense mechanisms against infection are categorized into two types: nonspecific and specific. Both types cooperatively function as an effective anti-infection system. Varied inflammatory cells are involved in the processes

2.1 Types of inflammatory cells

Types of inflammatory cells and their properties are briefly summarized in Table 1. Function of the cells and their proliferative and migratory activity are shown.

Cell type Function Proliferative activity Migratory potential
 Neutrophil Phagocytosis None Migratory
 Eosinophil Allergy, anti-helminth function None Migratory
 Basophil Histamine production None Migratory
Mast cell Histamine production Proliferative Migratory
Monocyte Phagocytosis Proliferative Migratory
Macrophage Phagocytosis, granuloma reaction Proliferative Migratory
B-lymphocyte Humoral immunity Proliferative Migratory
T-lymphocyte Cellular immunity/helper activity Proliferative Migratory
NK cell Innate immunity Proliferative Migratory
Plasma cell Antibody production None None
Dendritic cell Antigen presentation Proliferative None

2.2 Nonspecific defense mechanisms against infection

2.2.1 Physical barriers

The epidermis of the skin and the surface mucosal layer on the mucosal membrane play an effective physical barrier against invasion of the pathogen. The cilia on the pseudostratified mucosa of the airway effectively excrete the pathogen.

2.2.2 Antibacterial secretory proteins

The secretory juice secreted from secretory glands contains varied antibacterial proteins such as lactoferrin, lysozyme (muramidase), and defensins. Lactoferrin shows a bacteriostatic function by combining and competing for trivalent ferric ions mandatory for the growth of bacteria and fungi. Lactoferrin is secreted from the lactating breast, serous salivary glands, lacrimal glands, eccrine sweat glands, gastric glands, and prostatic glands. Of particular note is that protease digestion of lactoferrin yields lactoferricin and lactoferrin, potent antimicrobial peptides derived from the lactoferrin molecule.

3 Phagocytes and natural killer (NK) cells

Bacteria are nonspecifically phagocytized by phagocytes such as neutrophils and macrophages exhibits bacteria phagocytized by neutrophils. Because of the lack of proliferative activity, neutrophils are predominantly seen in acute inflammation. Macrophages are proliferative so they mainly appear in chronic inflammation. Myeloperoxidase, lysozyme, and defensins show bactericidal activities in the phagocytic vacuole (primary granule) of the neutrophil ]. In the secondary (specific) granule of neutrophils, lactoferrin is contained. The main bactericidal enzyme functioning in the macrophage is lysozyme  NK cells correspond to CD56-positive large granular lymphocytes.

2.2.4 Innate immunity and Toll-like receptors

Acute viral infection usually calms down in one week. The strong anti-viral mediators are type I interferons (IFN-alpha and IFN-beta). The IFNs are produced by the keratinocyte of the epidermis and squamous mucosa, the columnar cells of the intestinal and airway mucosa, and Langerhans (dendritic) cells distributed among the epithelial cells ]. Toll-like receptors (TLRs) expressed on these cells specifically recognize microbe-derived components such as lipoproteins, lipopolysaccharide, viral double-stranded RNA, non-methylated CpG islands of DNA, and flagellin to induce IFN secretion.

2.3 Specific defense mechanisms against infection

The specific acquired immunity consists of humoral immunity and cell-mediated (cellular) immunity. The production of specific antibodies by B-lymphocytes is the key mechanism of humoral immunity. Serum complements secreted from the liver activate the neutralizing the activity of specific antibodies. The key players of cell-mediated immunity are cytotoxic (killer) T-lymphocytes and activated macrophages. It takes a certain period (usually two weeks to one month) until establishing the specific acquired immunity.

The specific defense mechanisms against infection should be divided into two categories: systemic immunity versus local (mucosal) immunity. The pathogen invading the inside of the body is specifically protected by IgG-mediated humoral immunity and also by CD8-positive cytotoxic T-lymphocyte-mediated cellular immunity.


2.4 Three major patterns of host responses against infection

From the pathological point of view, there are three major mechanisms of host responses against infection, depending on the type of pathogens and the mode of infection (either extracellular or intracellular infection).

  1. Neutrophilic reaction against extracellular pathogens

  2. Cellular immune reaction against intracellular pathogens

  3. Humoral immunity via neutralizing antibody reaction

 summarizes the features of the defense mechanisms and host responses against pathogens. Patterns of the host response against pathogens are listed up

Defending cell type Pathogen Host response Compromised condition
Neutrophils Extracellular pathogens Abscess/phlegmone Neutropenia
T-cells/Macrophages Intracellular pathogens Granuloma/lymphocytic infiltration Cellular immunodeficiency*
B-cells/Neutralizing antibodies Bacterial capsule/exotoxin viremic viruses Not specified Complement deficiency

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