First drugs
Rifamycins were first isolated in 1957 from a fermentation culture of Streptomyces mediterranei at the laboratory of Gruppo Lepetit SpA in Milan by two scientist named Piero Sensi and Maria Teresa Timbal, working with the Israeli scientist Pinhas Margalith. Initially, a family  of closely related antibiotics was discovered referred to as  Rifamycin A, B, C, D, E. The only component of this mixture sufficiently stable to isolate in a pure form was Rifamycin B, which unfortunately was poorly active. However, further studies showed that while Rifamycin B was essentially inactive, it was spontaneously oxidized and hydrolyzed in aqueous solutions to yield the highly active Rifamycin S. Simple reduction of Rifamycin S yielded the hydroquinone form called Rifamycin SV, which became the first member of this class to enter clinical use as an intravenous antibiotic. Further chemical modification of Rifamycin SV yielded an improved analog Rifamide, which was also introduced into clinical practice, but was similarly limited to intravenous use. After an extensive modification program, Rifampin was eventually produced, which is orally available and has become a mainstay of Tuberculosis therapy

Lepetit filed for patent protection of Rifamycin B in the UK in August 1958, and in the US in March 1959. The British patent GB921045 was granted in March 1963, and U.S. Patent 3,150,046 was granted in September 1964. The drug is widely regarded as having helped conquer the issue of drug-resistant tuberculosis in the 1960s. Clinical trials
Rifamycins have been used for the treatment of many diseases, the most important one being HIV-related tuberculosis.
A complement receptor is a membrane-bound receptor belonging to the complement system, which is part of the innate immune system. Complement receptors bind effector protein fragments that are produced in response to antigen-antibody complexes or damage-associated molecules. Complement receptor activation contributes to the regulation of inflammation, leukocyte extravasation, and phagocytosis; it also contributes to the adaptive immune response. Different complement receptors can participate in either the classical complement pathway, the alternative complement pathway, or both. Expression and function
White blood cells, particularly monocytes and macrophages, express complement receptors on their surface. All four complement receptors can bind to fragments of complement component 3 or complement component 4 coated on pathogen surface, but the receptors trigger different downstream activities. Complement receptor (CR) 1, 3, and 4 function as opsonins which stimulate phagocytosis, whereas CR2 is expressed only on B cells as a co-receptor. Red blood cells (RBCs) also express CR1, which enables RBCs to carry complement-bound antigen-antibody complexes to the liver and spleen for degradation. a.^ B: B cell. E: erythrocyte. Endo: endothelial cell. D: dendritic cell. FDC: follicular dendritic cell. Mac: macrophage. MC: mast cell. M0: monocyte. Pha: phagocyte. PMN: polymorphonuclear leukocyte. Clinical significance
Deficits in complement receptor expression can cause disease. Mutations in complement receptors which alter receptor function can also increase risk of certain diseases. See also
Complement system
Humoral immunity
Immune system

References
External links
Complement+receptors at the US National Library of Medicine Medical Subject Headings (MeSH)