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Vaccines are important for providing protection from infectious diseases. Vaccination initiates a process that stimulates development of a robust and long-lived immune response to the disease agents in the vaccine. Side effects are sometimes associated with vaccination. These vary from development of acute hypersensitivity responses to vaccine components to local tissue reactions that are annoying but not significantly detrimental to the patient. The pathogenesis of these responses and the consequent clinical outcomes are discussed. Overstimulation of the immune response and the potential relationship to autoimmunity is evaluated in relation to genetic predisposition., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Pneumonic pasteurellosis (PP) is an economically important disease in cattle, sheep, and goats. Pasteurella haemolytica is commonly isolated from the severe fibrinopurulent pneumonia that characterize this respiratory syndrome. During infection, the bacteria produce leukotoxin (LKT) and lipopolysaccharide (LPS), both potent inducers of inflammation. Nonetheless, it has also been demonstrated that an exacerbated host's inflammatory response is responsible for the severe lung damage. Despite research in this field, the pathogenesis of PP is still incomplete. Two classical models of acute inflammatory response induced in laboratory animals, the Arthus and Shwartzman reactions, could explain the pathogenesis of the severe lung lesions that characterize PP.

Chicken basophils showed phagocytosis of carbon particles in reversed passive Arthus reaction, induced in the skin. Heterophils, monocytes and thrombocytes also contained carbon particles, but eosinophils revealed them only occasionally. The findings suggest that basophils may share phagocytic properties with other cells under immunological stimulus.

It was possible to produce an active Arthus reaction in chicken skin which resulted in gross and microscopic lesions. Histologically, the reaction was predominantly thrombotic in nature and restricted to the upper dermis. The thrombi appeared to develop as a consequence of immune complex deposition with adherence and aggregation of thrombocytes at the vascular endothelium. Thrombosis induced widespread necrosis and haemorrhage and vasculitis occurred in the lower dermis. Up to four hours after inoculation, the cell population comprised an infiltration of heterophils, monocytes and basophils, suggesting an immediate hypersensitivity reaction. This was followed by an Arthus type reaction for four to 12 hours involving both heterophils and monocytes. A characteristic feature was the development of early perivascular lymphoid foci. After 12 hours the reaction resembled a delayed hypersensitivity. The use of colloidal carbon suggested that whereas phagocytic activity of the heterophils and basophils appeared sensitisation dependent, that of thrombocytes and monocytes was independent of it. The findings indicate that in the Arthus reaction in the chicken the thrombocyte appears to be the principal cell producing tissue damage by thrombosis. A comparison was made with the active Arthus reaction in the rabbit.

Protein species found in crude extracts of Hypoderma lineatum (Villers) 1st-instar gullet-stage larval homogenates were fractionated by chromatography and further identified by conventional polyacrylamide gel electrophoresis (PAGE) and SDS/PAGE techniques. Seven major fractions were resolved by ion exchange chromatography. Conventional PAGE of the crude antigen preparation revealed a minimum of 14 protein species, while SDS/PAGE revealed 3 major protein species. The ability to elicit cutaneous reactivity by isolated proteins was determined by the intradermal skin test. An immediate-type hypersensitivity reaction was elicited in the skin of vaccinated and previously infested animals by the components of the 4 protein fractions tested. Only one protein fraction, fraction 4, elicited an apparent delayed reaction at 48 h in vaccinated and previously infested animals. A non-specific background reaction was elicited in control animals by the fractionated proteins and was most notable between 1- and 4-h post-injection.