| • | immune complex disease = type III hypersensitivity |
| • | (in some diseases, circulating immune complexes may be formed secondary to tissue damage that has occurred through cell-mediated or other mechanisms) |
serum sickness
| • | occurs 8 to 12 days after the subcutaneous injection of the horse diphtheria antitoxin |
| • | fever, lymphadenopathy, arthralgias, leukopenia, urticaria, and albuminuria |
| • | SLE/ serum sickness similar: glomerulonephritis, arthritis, and vasculitis |
| • | a possible explanation of the continued circulation of the immune complexes in patients with SLE has been the defective function of the RES reticuloendothelial system in these patients |
arthus reaction
| • | elicited by: immunizing an animal with a foreign protein and then injecting the antigen into its skin |
| • | reaches peak intensity between 4 and 10 hours later |
| • | characterized by erythema, edema, hemorrhage, and necrosis |
| • | clinically, histologically, and immunopathologically similar to LCV in humans |
whenever immune complexes are deposited, they activate the complement system, neutrophils are attracted to the site (C5a) and inflammation and tissue injury occur:
| • | erythema marginatum (may be true urticaria vs. variant of the figurate erythemas) |
| • | serum sickness prodrome of Hepatitis B (histology = LCV) |
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| • | purpura (+/- palpable)/ulcers |
| • | immune complexes cause arthritis and glomerulonephritis |
the link is the neutrophils though there are other causes of neutrophil activation (which is why some diseases are in one group and not all 3)
| • | pathogenic group = immune complex disease |
| • | histologic group = neutrophilic dermatoses |
| • | clinical group = pustular diseases |
IMMUNE COMPLEX DISEASE (and neutrophil diseases) (by antigen)
| • | group A beta hemolytic strep |
| • | PSGN post-streptococcal glomerulonephritis |
| • | SBE subacute bacterial endocarditis and chronic bacterial endocarditis |
| • | erythema nodosum (neutrophilic dermatosis) |
| • | Sweet’s syndrome (neutrophilic dermatosis) |
| • | acute guttate psoriasis (TH1, neuts on path) |
| • | other: bowel associated dermatosis-arthritis syndrome |
| • | IBD inflammatory bowel disease (--> PG, e. nodosum) |
| • | AML = neutrophilic leukemia (--> Sweet’s, neutrophilic eccrine hidradenitis) |
| • | erythema elevatum diutinum |
| • | self-antigens/connective tissue disease |
| • | IgG – rheumatoid factor = IgM vs. Fc portion of normal human IgG |
| • | DNA – SLE immune complexes |
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