Pulmonary surfactant is a surface-active lipoprotein complex (phospholipoprotein) formed by type II alveolar cells. The proteins and lipids that make up the surfactant have both hydrophilic and hydrophobic regions.
Antibody deficiencies, also called immunoglobulin deficiency syndromes, are immune system disorders that are characterized by low or absent levels of immunoglobulin in the blood.Immunoglobulins (Ig) are antibodies that play an essential role in the body's immune system.he antibodies are present in the bloodstream or bound to the outer surfaces of B-cells or plasma cells. There are five classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM. Patients who have antibody deficiencies may have reduced or absent levels of one or more types of immunoglobulin.
Presentation [edit]. Type III hypersensitivity occurs when there is an excess of antigen, leading to small immune complexes being formed that do not fix complement and are not cleared from the circulation. It involves soluble antigens that are not bound to cell surfaces (as opposed to those in type II hypersensitivity).When these antigens bind antibodies, immune complexes of different sizes form. Large complexes can be cleared by macrophages but macrophages have difficulty in the disposal of small immune complexes.These immune complexes insert themselves into small blood vessels, joints, and glomeruli, causing symptoms.hen these antigens bind antibodies, immune complexes of different sizes form. Large complexes can be cleared by macrophages but macrophages have difficulty in the disposal of small immune complexes. These immune complexes insert themselves into small blood vessels, joints, and glomeruli, causing symptoms.