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Fluorescence patterns of cytoplasmic autoantigens

Autoantibodies recognizing antigens of cytoplasmic organelles

There are many important organelles in the cytoplasm which fulfill various functions of the cell as described in section 1. Various autoantibodies, known as anti-cytoplasmic antibodies, targeting the proteins organizing these organelles and many cytosol proteins have been found.

Anti-mitochondrial antibody

photo 44

photo 45
Staining of AMA-M2 using rodent kidney and stomach sections as substrates. Cytoplasmic staining in the renal tubular cells (intense staining in the distal tubular cells) and intense fluoresence in the parietal cells of the stomach are observed.

Pattern Coarse granular filamentous staining extending throughout the cytoplasm.
Antigen Anti-mitochondrial antibodies-M2 (AMA-M2): pyruvate dehydrogenase (PDH-E2), located on the inner mitochondrial membrane. Antibodies to AMA-M1 and sub-patterns of AMA-M3 to M9 were reported. The staining shown here is due to AMA-M2 antibodies.
Other analytical method IF (rodent kidney or stomach sections used as substrates), ELISA, WB, CLEIA
Clinical significance These antibodies occur frequently in patients with PBC and their presence constitutes one of the diagnostic criteria of the disease. Recently, the presence of mitochondrial autoantigen in bile was reported.
References 53, 54

Anti-ribosomal antibody

photo 46

photo 47
Staining of anti-ribosomal antibody using rodent kidney and stomach sections as substrates. The diffuse staining in the kidney tubular cells and fluorescence of the chief cells of the stomach are observed. (Comparatively, anti-mitochondrial antibodies fluoresce in the pariental cells of the stomach.)

Pattern Homogeneous cytoplasmic staining with perinuclear accentuation is associated with nucleolar staining.
Antigen 3 phosphoproteins of 60S ribosomal particles (P0(38kD), P1(19kD), and P2(17kD)), 28S ribosomal RNA, L12 protein
Other analytical method IF, DID, WB, Immunoprecipitation
Clinical significance These antibodies occur in patients with SLE associated with neuropsychiatric symptoms. Presence in scleroderma patients was also reported.
References 55, 56, 57

Anti-Jo-1 antibody

photo 48    AF/CDC-10*

Pattern Fine granular speckled cytoplasmic staining, but weak fluorescence is usual. The granules are condensed around the nucleus and diminish toward the periphery of the cell. The reference serum of AF/CDC-10 from CDC rarely stains in the usual dilution of the test. It was reported that Jo-1 antigens exist in both nucleus and cytoplasm.
Antigen Histidyl-tRNA-synthetase (catalyzing the binding reaction of histidine to 3'-OH of tRNAHis)
Other analytical methods DID, ELISA, Immunoprecipitation, CLEIA
Clinical significance These antibodies occur specifically in patients with PM/DM, and is frequently associated with interstitial pulmonary fibrosis and polyarthritis. The presence of these antibodies consititutes one of diagnostic criteria for PM/DM.
References 2, 58

* Reference serum from Centers for Disease Control

Antibodies to other aminoacyl-tRNA-synthetases (described below) showing similar staining patterns to anti-Jo-1 antibody are found in patients with polymyositis and dermatomyositis. [Reference: 59,74, 75]
Anti-PL-7 antibody … threonyl-tRNA synthetase
Anti-PL-12 antibody … alanyl-tRNA synthetase
Anti-OJ antibody … isoleucyl-tRNA synthetase
Anti-EJ antibody … glycyl-tRNA synthetase
Anti-KS antibody…asparaginyl-tRNA synthetase

Antibodies to the signal recognition particle (SRP) show fine dense speckled cytoplasmic staining, and is highly specific to polymyositis. The targeting 54kD protein of SRP bind to the rough endoplasmic reticulum and ribosomes. In patients with these antibodies, poor response to therapy and frequent recurrence are characteristically observed.[Reference: 60]


Anti-lysosomal antibody

photo 49

Pattern Large speckles distributed throughout the cytoplasm fluorescence.
Antigen Lysosomal proteins. The enzymes in lysosomes like cathepsin and lysosome-associated membrane proteins (LAMPs) are considered as candidate antigens. However, they are poorly characterized.
Clinical significance These antibodies occur infrequently in patients with SLE. Clear clinical associations are not known.
References 1, 2


Anti-Golgi apparatus antibody

photo 50

Pattern Irregular discontinuous granular staining in cytoplasm around the nucleus.
Antigen 230kD protein of Golgi apparatus. Recently 97kD (golgin-97) and 200kD non-myosin proteins were reported.
Clinical significance These antibodies occur infrequently in patients with SLE and SS. The Golgin-97 was reported to be specific to secondary SS.
References 61, 62


autoantibodies recognizing the protein components of various organelles in cytoplasm

The photos shown below suggest the presence of autoantibodies recognizing the protein components of various organelles in cytoplasm, the enzymes in vesicles and secretory granules or degraded substances taken into the vesicles. They show dense-to-coarse cytoplasmic staining, but the corresponding antigens are not determined. Photo 54 shows the pattern relevant to cell cycle.

photo 51
Dense staining throughout cytoplasm.

photo 52
Same as photo 51, but more coarse staining.

photo 53
Similar staining to the mitochondrial antibodies but the speckles are different.

photo 54
Some of the cell populations show cytoplasmic staining.


SLE: systemic lupus erythematosus, SSc: systemic sclerosis, MCTD: mixed connective tissue disease, SS: Sjögren's syndrome, PM/DM: polymyositis/dermatomyositis, RA: rheumatoid arthritis, PBC: primary biliary cirrhosis, AIH: autoimmune hepatitis

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