Abstract: Processes of diagnosing or treating an autoimmune abnormality are provided whereby the presence of IgA anti-neutrophil cytoplasmic antibodies (ANCA) in a subject are detected correlating with both presence and severity of disease such as Wegener's granulomatosis (WG). The FCAR genotype predicts whether IgA ANCA will be stimulatory or inhibitory of neutrophil activation such that in subjects with an inhibitory genotype, IgA ANCA will act as an inhibitor of disease severity, and in subjects with a proinflammatory genotype, IgA ANCA will increase disease severity as observed by increased prevalence of renal disease in WG. Thus, individualized medical treatment is possible based on determination of the presence of IgA ANCA and FCAR genotype.

Abstract: The discovery of Fc?RIIc expression on B-cells allows several new methods of prediction or regulation of immune responses. A process of altering an immune response in a subject is provided by altering the expression level or activity of Fc?RIIc on a cell. The relative ratio of activating Fc?RIIc to inhibitory Fc?RIIb levels in an immune cell allows prediction of the presence or absence of immune disease or abnormality such as rheumatoid arthritis or systemic lupus erythematosus. Inventive processes are provided whereby the relative levels of activating to inhibitory receptor expression in a subject is compared to an established inventive classification system to predict an immune response to a therapeutic, the presence or absence of disease, or the magnitude, duration, or timing of an immune response in the subject.

Abstract: The present invention provides a method for determining whether a patient has a predisposition to infection by certain encapsulated bacteria. The method involves determining whether the Fc&ggr; receptor allelic pattern of the patient corresponds most closely to known Fc&ggr; receptor allelic patterns of patients having no infection.

Abstract: The present invention provides a method for identifying Fc.gamma.RIIIA allelic pattern in a human patient. The present invention also provides methods for determining in a human patient a predisposition to autoimmune diseases and the relative capacity of a human subject to produce anti-tumor antibodies, antibodies directed against viral or bacterial pathogen, or to mount an effective immune response to a vaccine.

Abstract: The present invention provides a method for determining whether a patient has a predisposition to develop severe forms of autoimmune disease. The method involves determining whether the Fc.gamma. receptor allelic pattern of the patient corresponds most closely to known Fc.gamma. receptor allelic patterns of patients having no autoimmune disease, mild autoimmune disease, or severe autoimmune disease. The invention also encompasses methods for determining if a patient has a predisposition to infection by certain encapsulated bacteria.