Rat haptoglobin: method of quantitation and response to antiarthritic therapy in collagen arthritis

Review of immunological plasma markers for longitudinal analysis of inflammation and infection in rat models

Disease or trauma of orthopedic tissues, including osteomyelitis, osteoporosis, arthritis, and fracture, results in a complex immune response, leading to a change in the concentration and milieu of immunological cells and proteins in the blood. While C-reactive protein levels and white blood cell counts are used to track inflammation and infection clinically, controlled longitudinal studies of disease/injury progression are limited. Thus, the use of clinically-relevant animal models can enable a more in-depth understanding of disease/injury progression and treatment efficacy. Though longitudinal tracking of immunological markers has been performed in rat models of various inflammatory and infectious diseases, currently there is no consensus on which markers are sensitive and reliable for tracking levels of inflammation and/or infection. Here, we discuss the blood markers that are most consistent with other outcome measures of the immune response in the rat, by reviewing their utility for longitudinal tracking of infection and/or inflammation in the following types of models: localized inflammation/arthritis, injury, infection, and injury + infection. While cytokines and acute phase proteins such as haptoglobin, fibrinogen, and α₂ -macroglobulin demonstrate utility for tracking immunological response in many inflammation and infection models, there is likely not a singular superior marker for all rat models. Instead, longitudinal characterization of these models may benefit from evaluation of a collection of cytokines and/or acute phase proteins. Identification of immunological plasma markers indicative of the progression of a pathology will allow for the refinement of animal models for understanding, diagnosing, and treating inflammatory and infectious diseases of orthopedic tissues.

Purification of mouse haptoglobin by antibody affinity chromatography and development of an ELISA to measure serum haptoglobin levels

Mouse haptoglobin was isolated from acute-phase serum initially by affinity chromatography on haemoglobin-Sepharose. This proved inefficient, but sufficient material was obtained for use as an immunogen. Rabbit anti-haptoglobin antibodies were used as immunoabsorbents to isolate larger quantities of haptoglobin. Subsequently, specific anti-haptoglobin antibodies were prepared by affinity chromatography on haptoglobin-Sepharose. A direct sandwich ELISA for mouse serum haptoglobin was developed, using affinity purified reagents. The working range of the haptoglobin standard curve was 0.02-0.5 microgram/ml. The reagents did not cross-react with albumin or haemoglobin and the antibody also recognised rat haptoglobin.