What Is I-Cell Disease?

Human T-cell prone virus (HTLV) is a tumorigenic RNA virus, belonging to the subfamily Lentivirus, which can be divided into HTLV- and HTLV-. Recently found that the virus can cause a variety of diseases in humans: HTLV-I can cause adult T-cell leukemia / lymphoma (ATL), tropical spastic paraplegia / HTLV-related myelopathy, etc .; HTLV- and T-hairy cells / giant Myeloid leukemia and other diseases.

Basic Information

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Internal medicine

Common causes

Human pro-T-cell virus infection

Common symptoms

The incubation period is uncertain. It can take years to decades for the elderly to develop clinical symptoms after being infected with HTLV.

Causes of human T lymphocyte virus infection

HTLV is a retrovirus that contains RNA and reverse transcriptase and is a tumorigenic RNA virus. Under the electron microscope, the virus particles are spherical with a diameter of 100 nanometers. The inner core is composed of structural proteins. The core shell and matrix (also known as P15, P24, and P19GAG proteins) surround the viral RNA and polymerase. The outer layer is virus envelope sugar. The proteins (surface and transmembrane glycoproteins, called GP46 and GP21, respectively) are embedded in a bilayer lipid membrane. The virus genome is 30S-35S positive-stranded single-stranded RNA, which is about 10 kb in length and has reverse transcriptase activity. The genome is arranged in order from the 5 ' 3' end into three structural genes gag-pol-env and two regulatory genes tax and rex, with LTR at both ends (long terminal repeats: RU5, U3). HTLV-I and HTL- have 65% nucleotide homology in the total sequence, but have the lowest homology in the LTR sequence (30%), and the highest among 3'tax / rex regulatory genes (75% 80%).

Clinical manifestations of human T lymphocyte virus infection

The incubation period of this disease is uncertain, and it can take several years to decades for the elderly to develop clinical symptoms after infection with HTLV. Recently, many diseases related to HTLV have been found.

Health status

HTLV-I antibodies can be detected in adults with high incidence of ATL, and HTLV-95% to 98% can be isolated from HTLV- antibody-positive lymphocyte cultures. Therefore, antibody positives are all HTLV carriers.

2. Adult ATL

Mainly caused by HTLV-. Based on clinical manifestations, Shimoyama divides them into 4 subtypes.

(1) Occult ATL is characterized by abnormal T cells accounting for 5% or more of the total number of normal lymphocytes in peripheral blood, accompanied by skin damage and occasionally involving the lungs. There was no hypercalcemia, lymphadenopathy, or visceral damage. Serum LDH (lactate dehydrogenase) levels may increase. This type of progress is slow and can often last for several years.

(2) Chronic ATL is characterized by an increase in the absolute number of lymphocytes (above 4 × 10 ^[9] / L), accompanied by T lymphocytosis (over 3.5 × 10 ^[9] / L), and serum LDH rises to normal 2 times. And there are lymphadenopathy, hepatosplenomegaly, skin and lung damage. No hypercalcemia, ascites and pleural effusions, or damage to the central nervous system, bone or gastrointestinal tract were present.

(3) Lymphomatic ATL lymphadenopathy without lymphocytosis. Histopathology must confirm lymphoma.

(4) Acute ATL includes some patients who remain and have high non-Hodgkin's lymphoma manifestations of leukemia or leukemia cells with blood. Hypercalcemia, lytic bone damage, and visceral damage are common. It can transition from acute to chronic at any stage of the disease.

3.T hairy cell / megaloblastic leukemia is associated with HTLV-

Fever, anemia, and splenomegaly are common features. At the same time, hairy cells can be found in peripheral blood and bone marrow with hypersplenism, portal hypertension, and ascites, as well as high levels of TNF- (-interferon).

4. Central nervous system damage

It is more common in people with HTLV- infection in 40-50 years old, and can show symptoms of meningeal lesions, such as meningeal irritation, changes in consciousness, etc .; symptoms of spinal cord disorders, such as weakness of the limbs, numbness or loss of toes, and tonic paralysis of the lower limbs.

Human T lymphocyte virus infection test

Cytological examination

Can be used for peripheral blood or bone marrow cytology. The diagnosis of adult T-cell leukemia / lymphoma is based on the discovery of abnormal leukemia cells, that is, medium-sized abnormal lymphocytes, with less cytoplasm, no particles, and sometimes vacuoles. Acute ATL shows irregular nucleus with multiple shape changes, distorted deformity or lobes, called flower cells; chronic type shows typical nuclear fission cells; insidious type also has characteristic cell morphology.

2. Serum HTLV-I / antibody detection

Currently, indirect immunofluorescence (IFA), gelatin particle agglutination (GPA), radioimmunoassay (RIA), enzyme-linked immunosorbent assay (ELISA), and Western blot test (WB) are mostly used. Antigens are commonly used in HTLV-infected cell line lysates, purified virions, synthetic peptides, or recombinant peptides. ELISA is currently the most commonly used detection method.

3. HTLV virus particles and antigen detection

Peripheral lymphocytes isolated from fresh blood of ATL patients or HTLV carriers were taken and cultured. The virus particles of the cells were observed with an electron microscope or the virus antigens on the cell surface were examined by immunofluorescence.

4.HTLV PCR detection

Conserved regions in the gag, pol, and env genes of HTLV were selected to design common primers and probes for HTLV-I and HTLV-II for PCR reactions.

5. Cerebrospinal fluid examination

For patients with central nervous system symptoms, cerebrospinal fluid examination can be taken. Generally, the protein content is high, which can reach 2.1g / L, and the gamma globulin level is high. There are high-titer HTLV antibodies, and lymphocytes and ATL-like cells.

Diagnosis of human T lymphocyte virus infection

Adults with mature T-cell lymphoma, hypercalcemia, and / or mucosal damage, especially in patients from high-risk HTLV populations or endemic areas, should consider the diagnosis of ATL. The diagnosis was based on serum HTLV-I antibody positive and HTLV-I provirus found in blood or white blood cells from biopsies.

Human T lymphocyte virus infection treatment

So far, there is no effective treatment method and antiviral drugs, and the prognosis of ATL is very poor with very few. Chronic spontaneous remissions usually die within a few years of the diagnosis. In the acute phase, ATL patients can receive chemotherapy, such as CHOP (cyclophosphamide doxorubicin, vincristine, and prednisone), but conventional treatments have limited effectiveness. The nucleoside analogue, deoxycostin, is effective in some cases.