Types of Hypersensitivity

yeah hi good evening one and all okay now I will be discussing few important things which are important in need point of view related to the students topic that is allergy and hypersensitivity okay of course it is one of the important topic in related to the community and I'll just go I mean like very precise in am secure point of view okay so coming to the basic classification of hypersensitivity which is given by Coombs and gel so initially the classification contains only four types that is type one immediate which is also called as nei a topic and anaphylactic these two types are subtypes in type one and the second one is antigen antibody mediated and third one is immune complex mediated and type 4 is cell mediated which is also called as knit delayed hypersensitivity and recently added is fifth one which is sometimes called within a subtype of type 2 means the fifth type will be a part of types - okay so we'll go in detail in respect to each and everything coming to the type one type one is immediate which is also called as in a atopic or anaphylactic okay so the type one is generally an allergic reaction that is provoking when it is reexpose to a specific antigen so if basic definition of hypersensitivity is very simple when you get exposed to a particular antigen the body will get sensitized to it so when you are repeatedly exposed to the same antigen the body will show some sort of reaction in the form of symptoms clinically that is called a hypersensitivity okay so the exposure for the type 1 can be either inhalation or injection or ingestion and it is mainly mediated by IgE antibodies or IG immunoglobulins and partially by cd4 th2 cells and marsh and as already said like a topi is a subtype of type one and it is caused I mean this Adobe is generally a genetically mediated which is under the control of chromosome number six yesterday we have viscous question and I'm security later to the chromosome number six that is H Elia complex is coded by the short arm of chromosome and number six Omega naught chromosome number six is important altitude and this causes an inflammatory response to and immediately it can be an immediate which can takes place in a few seconds two minutes or it can be prolonged and it can be either local or systemic and the symptoms ranges from mild irritation to sudden depth due to an electric shock okay so the treatment options are you need to prevent this for this you need to do and histamines you need to you epinephrine you need to do corticosteroids so this is the basic treatment option will be discussing the treatment options in detail further so a simple physiology how it goes like whenever this pathogen whenever this allergen or whenever this antigen enters it's sensitized and activates the IgE production once the IC is produced IC is going to bind to the marsh cells with this FC receptor so when repeated exposure of the same antigen occurs the mast cells get activated and they release the calcium whenever the calcium rises and the calcium religious and this is going to give you the clinical outcome of the clinical effect so some common examples I mean your pamper your MCQs will mainly moose in these common examples they just give okay this particular SD phenomenon is seen with which type of hypersensitivity that is type 1 okay you taqueria seen with which type of hypersensitivity hi favor seen with roots type of hypersensitivity anaphylactic shock is related to which type of hypersensitivity these are the most commonly asked questions so please make a note of all of these examples examples are the most important thing when we talk about hypersensitivity okay so some dental materials will be concerned with type 1 hypersensitivity but most of the dental materials will show type 4 hypersensitivity the most common into industry okay 10 - material related hypersensitivity type for if they ask both type 1 as well as type 4 type 4 is more compared to type 1 so make a note that is more important rather than anything here ok so we are done so the next one is about the treatment option for this hypersensitivity the basic treatment option how we need to go ahead the documentation everything you should make a note and whenever this anaphylactic shock is there you need to take a few precautions of this maintaining of ABCD a way everything and everything should be maintained CPR if necessary should be done all these are basic things you just go with the slide and I'm not going to discuss much about this but the main important aspect is forma logical management if you go to the first treatment that is for a moderate reaction intramuscular injection of epinephrine one is to 1000 0.3 to 0.5 milligrams is star and C true so just make a note of all of these just go through them first and second lines are most commonly asked as an excuse and of course corticosteroids too so just just go with these slide it's very important so the most commonly recent last questions is the most important cell in type 1 hypersensitivity is cd4 pH 2 cell and the most important cell in the late phase of the type and hypersensitivity is Norfolk ok these are the most two important things that you have to have a look so coming to the type 2 type 2 is antibody mediated okay of course you know that the body can have the sense to recognize the self antigen self cells and non-self cells okay which are like foreign bodies so that is main main main concern in the case of a type 2 antibody dependent type 2 and upon to dependent his antibody produced by the produced by the immune response to bind to the antigen on the patient's own cells surface and it can be an intrinsic or an extrinsic intrinsic is antigen present on the parent I mean the patient cell whereas an extrinsic is some object is observed on to the I mean the parent cell as a foreigner as a foreign antigen is called as an extrinsic and the main immunoglobulins that are concerned with this type 2 hypersensitivity is IgG an idea and they go with in a classical pathway okay the the complement system which is concerned with this type of hypersensitivities classical pathway so make a note the immunoglobulins that are present in the classical pathway are i GG and IgM as well as the immunoglobulins that are more concerned to that of the type 2 hypersensitivity are again IgG and IgM okay this is very very important and the mechanism by which they causes this acute inflammation is by the membrane attack complex which causes the lysis and that will be discussing about the pathophysiology in detail so this is a simple like I mean in simple terms the type 2 hypersensitivity is exhibited by three mechanisms one is let I just want to make it as simple as possible the first mechanism is phagocytosis phagocytosis mechanism okay in this phagocytosis mechanism the main phenomenon is generally by the activation of IgG and IDC and IgM so whenever this IgG is activated okay it get sensitized with FC receptor and it's causes oxidation and phagocytosis and similarly ITC and Isaiah they activate saw the activates the c3 B and C for B okay which calls this phenomena this is one type of activation of this type 2 hypersensitivity and the second mechanism is whenever the I mean like self-reactive B cells are activated self-reactive B cells are activated during the reaction it's going to activate the IgM and it's going to activate the IgG with the help of cd4 T helper cells so whenever these two are activated it attaches to the host system either in the attachment either by the intrinsic as well as an extrinsic which is already discussed and if you go further in detail whenever an antigen which is coming from the extrinsic is attaching to the host cell immediately the body sends this IgG so this aunty this immunoglobulin which is also called as an antibody is going to react with this antigen which is present on the surface of the host cell to form antigen-antibody complex so whenever this antigen-antibody complex is formed there will be activation of complement system so the complement system activation takes place by two mechanisms one is immediately the C one is going to get activated with FC portion the C one is going to activate the C 2 C 3 C 4 and C 5 okay so out of these complement components few components they get lysis lysis and they're differentiate into two parts that is C to differentiate into C 2 a C 2 B similarly 3 C 3 a c 3 b c 4 h c4 b and c 5 s c 5 ok out of these the a components that is c 3 a c 4 a c 5a they act as an a chemo tactic factors okay so these chemotactic factors they extract the neutrophils and they causes the degranulation and they causes the cell in depth okay because it's seldom this is one mechanism and the second mechanism is the by the activation of the second component the second component left over is C Phi B with c6 c7 and c8 and multiple c9 factors means many c9 factors they combine to form a membrane attack complex okay that is called as net mca this mca is going to inject or it's going to penetrate into the cell membrane and it opens the cell memory whenever it opens the cell membrane due to the osmotic differences the fluid moves inside and the cell wall i mean the cells will swallows and the cell will lysis so these are the three mechanisms by which the type 2 hypersensitivity activates that one is by phagocytosis second one is by the neutrophil degranulation okay third one is by the lysis that is also stated with the mca molecules okay so these are the few examples the phagocytosis examples are autoimmune hemolytic anemia autoimmune thrombosis thrombocytopenia and inflammation related or good poster syndrome some fingers vulgaris and acute rheumatic fever and the cellular dysfunction sir you can just make a note of these examples these examples are very very important coming 2 type 3 type 3 is called as an immune complex mediated it occurs due to the immune complex antigen antibody reactions which are not removed from the circulation and this is most commonly seen in the various tissues but most frequently seen in the case of a kidneys joints lungs and skin so the mechanism is very simple okay in the first phase a large quantities of soluble antigen antibody complexes are formed in the blood and they are not removed by the macrophages this is the basic mechanism by which the type 3 hypersensitivity starts and the second one is this is antigen antibody complexes or discharged into the capillaries between the endothelial cells in the basement membrane so initially they are in the middle now they are disclosed into the space between the basement membrane and endothelial cells they are these are the antigen antibody complexes and the third phase is the Z antigen antibody complexes they activate the c1 that is classical component pathway leading to the vasodilatation of this particular area so further activation of complement system is completed and they they attracts these leukocytes to the particular area so the local leukocytes shows their action release the killing agents and they destroy the and they destroy and causing massive inflammation leading to cell death and humerus right so these are the basic examples that you have to make a note ok serum sickness post streptococcal glomerular nephritis okay system equal opposite dramatis these are the most commonly asked questions related examples and the rest examples you can just go ahead with the dental pulse and coming to the type for has already said it is a cell mediated or delayed type of hypersensitivity and it is mostly mediated by the T lymphocytes and in specific it is cd4 T H 1 and 17 ok 1 and 17 are more concerned with this whereas T 2 T 2 is more concerned with type 1 ok cd4 T 2 is more concerned with type 1 and cd4 th 1 and th 17 are more concerned with type 4 and classical and the most common example is Chebarkul and reaction will be we will be learning about the tuberculin reaction further in detail okay so I mean this is taken from a decent book the beautiful reference you just learn this okay the standard diagnostic test for the latent we're closest is chipper clean skin dust okay basically it is of two types one is the Chebarkul intest okay menthe rocks text and second one is half stressed so in this in this small truck stress what you're going to do is very simple you are going to inject the PPD that is the peptide derived molecules into the dorsal aspect of the forearm and you are going to observe it you are going to observe for the in duration and the palpated area after 48 to 72 hours and you have to measure that okay if the integrator area is greater than five millimeters okay for one international unit of PPD if it is one international unit of PPD if it is greater than five millimeters then it can be considered as positive if you are giving five units it should be greater than ten millimeters so in such cases you can be considered it doesn't bother to just go ahead read read completely completely about this read this slide is very important and second one is something like a gun okay that is a half test is something like a gun which consisting or has six needles and you need to press on the dorsal aspect of the skills and in this test they have given gradings the gratings are ranging from frying fry gratings that is great zero no reaction grade one is less than four discrete papillae and great to you just go ahead okay this is also it's very very important these two tests are very important and they have seen many questions related to these two tests and coming to the rest of the examples that are related with the type 4 hypersensitivity few autoimmune diseases and infectious diseases are present tuberculosis leprosy histoplasmosis toxoplasmosis please make a note of each and everything make a no traumatic arthritis will come here and rheumatic fever will be coming in the type 3 hypersensitivity okay so make a note and but the most important question related to this is majority of the dental materials they show type 4 delayed hypersensitivity okay so the last but not the least it's a new one it's a very very rare condition they can call it as in a subtype of type 2 hypersensitivity and the most common examples of the Graves disease when mice to migrate if you find option 5 whenever they ask questions related to my smugness of Graves disease if you find type 5 hypersensitivity you go for it if you don't find type I hypersensitivity you can go for type 2 hypersensitivity because it is a subtype of type 2 hypersensitivity and one of the most commonly seen diagram is question related to the hypersensitivity is patched as don't don't don't I mean like don't confuse with the Petacchi okay pathology test is related to the Bechet syndrome and pass test is related to the allergic okay if you want to identify the allergen that is causing the disease you are going to attach a patches of all the collected allergens onto the body and you are going to see the integration okay this is a method of pax test and one more question is the hypersensitivity associated with the dental materials it's type 4 and type 1 and the most common hypersensitivity associate with the dental materials in Skype for make you related hypersensitivity in attics close hypersensitivity and everything it comes under the type 4 hypersensitivity very very I mean in few conditions you can see type 1 hypersensitivity in the dentistry also materials okay that's all guys I hope this is a useful video for you and will be coming with a few more updates like this for a specific and important prophet SAS as hypersensitivity is one of the specific topic and I mean directly or indirectly you need some sort of concept oriented things related to this so that's the reason why we have made a video probably will be coming with more and more videos for you we are done for today all the best keep working hard