Reactive Information and Courses from MediaLab, Inc.

Rule-out (also referred to as exclusion or cross-out) is a process by which antibodies are identified as being unlikely in a given sample because of the absence of an expected antigen-antibody reaction. In other words, the absence of a reaction is noted with a cell that is positive for the corresponding antigen. Non-reactive cells are selected for rule-out. To be classified as non-reactive, a cell must NOT have reacted in any phase of testing in a given panel or screen. In the case of cold antibodies: if reactions are only occurring at immediate spin and are negative in the AHG phase, then that panel cell can be used as a rule out cell for IgG reactive antibodies but not for antibodies that react at immediate spin (IgM).If there is no reaction with a panel cell then it is possible that antibodies to the antigens on that cell are not present in the sample being tested. Based on Fisher's statistical probability recommendation, the probability of having reliable results increases if you are able to have more rule-out and rule-in cells. By comparing the patterns of reactivity and non-reactivity, we can more safely assume that an observed pattern is not the result of chance alone. If a "3 (reactions) to rule in and 3 (reactions) to rule out" protocol is used, there is then a 95% probability that the reaction pattern is not due to chance alone. Homozygous cells are used so that weaker reacting antibodies which fail to react to the antigen present in the heterozygous state aren't accidentally ruled out. Examples of Homozygous and Heterozygous Antibodies Jka Jkb Patient IS Patient AHG Panel cell 10 + + 0 2+ Panel cell 11 0 + 0 4+ Panel cell 10 shows Jkb in the heterozygous state. The patient's reaction is weaker than the reaction with panel cell 11 which shows Jkb in the homozygous state.Reactions are weaker when antigens are present in the heterozygous state because there is less of the antigen present for the potential antibody to bind with.

A reactive pia arachnoid mesothelial cell as noted by the darker cytoplasm is present in this field. Reactive cells are a common finding in cytospin smears from spinal fluid samples and are sometimes difficult to distinguish from tumor cells. Mesothelial cells are usually interspersed among the other cells, rather than appearing in clumps. They have a single distinct nuclei that may be eccentric. The macrophages (histiocytes) are seen next to the mesothelial cell. Macrophages are distinguished from circulating monocytes by the irregular appearing cytoplasm. Bacteria, red cells or other debris can often be seen in the cytoplasm of macrophages.

Smith KR, Fisher HC III, Hook, EW III: Prevalence of fluorescent monoclonal antibody-nonreactive Neisseria gonorrhoeae in five North American sexually transmitted disease clinics.J Clin Microbiol 34:1551-1552, 1996We compared a direct fluorescent monoclonal antibody (DFA) test with alternative enzymatic and fermention tests for identifying presumptive gonococcal isolates in a systematic sample from patients attending five sexually transmitted disease clinics in five cities.Fourteen (2.5%) of 556 isolates from three clinics were nonreactive with the DFA confirmatory reagent and reactive by both the Quad-Ferm and Rapid NH tests. The prevalence of DFA-nonreactive Neisseria gonorrhoeae isolates varies geographically and is independent of local methods for the identification of possible gonococci.On the basis of our findings, we recommend that for use in medicolegal and other instances in which a diagnosis of gonorrhea has the potential to have far-reaching effects, it is appropriate to test DFA reagent-nonreactive, oxidase-positive, gram-negative diplococci by alternative methods of gonococcal confirmation.Although the prevalence of such isolates could change, the fluorescent monoclonal antibody confirmation reagents remain useful for many clinical situations. Their ease of use and ready applicability for screening large numbers of isolates make them useful for many laboratories.

Free radicals are well known to occur in biological systems. A free radical is an atom or small molecule with unpaired electrons. These unpaired electrons make the atom or molecule highly reactive and unstable. Free radicals are produced constantly via metabolic processes. They are also released by immune cells. Immune cells can undergo 'oxidative bursts' (also called respiratory bursts) to help fight pathogens. Oxidative bursts can help degrade pathogens phagocytosed by immune cells and therefore free radicals have an important role in immune system function.However, free radicals also have detrimental effects on surrounding cells. When LDL is co-localized with cells or tissues that are releasing free radicals (such as in an inflamed vessel wall) the free radicals can chemically modify the phospholipids and other components of the lipoprotein. The LDL becomes oxidized and the modification makes the LDL more atherogenic.

Hereditary hemochromatosis (HH) is a genetic disorder characterized by iron overload as a result of increased iron absorption. As iron absorption increases, the amount of iron bound to transferrin and transported in the plasma subsequently increases.With no available mechanism for excreting excess absorbed iron, normal iron storage sites become overloaded, resulting in ferritin levels that far exceed normal. As a result, iron is deposited in the parenchymal cells of the liver, pancreas, pituitary, heart, synovium, and other tissues with high concentrations of transferrin receptors. Iron in excess of normal cellular ferritin stores contributes to the generation of free radicals and reactive oxygen intermediates that cause cell damage to organs and tissues. This process results in the clinical condition known as iron overload, a hallmark feature of HH.

In 1900, a German scientist, Karl Landsteiner, discovered that blood groups differ from one individual to another. He took blood samples from five associates and himself, allowed them to clot, and then separated the serum from the cells. Landsteiner found that when he mixed the serum and red cells from different individuals, some samples clumped and some didn’t. Our present day classification of the ABO system is based on Landsteiner’s realization that agglutination occurred because of highly reactive antigens present on the red blood cell which corresponded to antibodies present in the serum. Landsteiner isolated and named the red cell antigens “A” and “B” and the corresponding antibodies “Anti-A” and “Anti-B.” If the red cells contained neither antigen, he called these cells “O”, representing zero antigens present. The fourth type of red cells, “AB”, was discovered in 1902 by Von Decastello and Sturli, associates of Landsteiner. “AB” cells contained both A and B antigens on their surface.

Failure Mode, Effect, and Criticality Analysis uses the opposite approach of Root Cause Analysis. Ways FMECA and RCA differ: FMECA is proactive and RCA is reactive. FMECA occurs during development and RCA occurs after-the-fact. FMECA prevents errors and RCA satisfies patients or requirements. FMECA helps processes to work and RCA changes processes that do not work. FMECA encourages good outcomes and RCA changes bad outcomes.

Lymphocytes "transform" in response to antigenic stimuli.Their nuclei becomes larger with more open chromatin and a greater degree of nuclear folding.The cytoplasm becomes abundant, the number of azurophilic granules may be increased and vacuoles may be present.The cytoplasmic membrane may be easily indented by surrounding red blood cells, resulting in a scalloped appearance of the cell's outer edge.These lymphocytes may also be referred to as reactive, activated or stimulated.

It is important to be able to recognize the presence of these changes and then identify them for several reasons:If the changes are pathological, their identification may aid the physician in diagnosing a specific condition.If the changes are not pathological, their identification alerts the physician to the fact that the changes are present, thus avoiding a possible misdiagnosis.If reactive, it indicates that although the cells are functioning normally, they are reacting to a stimulus. Indicating the presence of such cells may aid in determining the diagnosis or monitoring the course of disease once a diagnosis has been made.

Plasma cells are uncommonly observed in the peripheral blood smear.They are normal constituents of lymph nodes, spleen, connective tissue and bone marrow. The presence of plasma cells in the peripheral blood is indicative of a large number of conditions mostly related to infections , immune disorders, malignancies, toxic exposures, hypersensitivity reactions and their responses.Although mature plasma cells have a distinct appearance, they still may be confused morphologically with immature plasma cells and other cells with inclusions, reactive changes or nucleated red bloods cell with altered identities.In the upper and lower photographs are plasma cells with features mindful of myeloma cellsThe large myeloma cell in the upper photograph has an eccentric immature nucleus with a muddy chromatin pattern.Note also clumping and stacking of the erythrocytes, bordering on rouleaux formation ,implicating an increase in plasma gamma globulin.The plasma cell with the double nucleus in the lower photograph is particularly suggestive of myeloma.Further studies are in order including a bone marrow examination where at least 30% of bone marrow cells should be variations of mature and immature plasma cells.Serum electrophoresis will reveal a monoclonal globulin spike, and light chains in excess of 1.0 gm/24 hours may be seen in the urine.The presence of lytic bone lesions is a convincing clinical clue.With these findings in combination, a diagnosis of myeloma can be made with assurance.