Activation of the complement system in human immunodeficiency virus infection: relevance of the classical pathway to pathogenesis and disease severity

Article Abstract:

The human immunodeficiency virus (HIV) produces a protein that interacts with the CD4 protein on T lymphocytes (cells that stimulate antibody production to fight infection), altering the function and decreasing the number of viable T lymphocytes. Patients infected with HIV have high levels of circulating immune complexes (CIC), which are potent activators of the complement system. The complement system consists of nine factors (designated C1 through C9) that become activated during infection to eliminate the invading pathogen. The three pathways for activating the complement system are called classical (C4d), alternative (Ba) and common (C3d). The importance of the three complement pathways in HIV infection was determined in 74 patients that tested positive for HIV. C4d, Ba and C3d were measured in blood samples and used as indicators of activation of the complement system. Levels of C4d, Ba and C3d were significantly higher in patients with HIV infection than in control patients that did not have HIV. Also, levels of CIC were higher, and T lymphocytes (with CD4) were lower in the HIV group. The reduction in CD4 lymphocytes was directly related to the severity of the HIV infection. The conversion of C4d to C4, resulting from activation of the classical pathway, increased as the infection progressed. It is concluded that the complement system is activated at all stages of HIV infection, and that activation of the classical pathway may be an indicator of disease severity. Determination of the activation of the classical pathway may be useful in monitoring HIV infection. (Consumer Summary produced by Reliance Medical Information, Inc.)

Development and progression

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Anticardiolipin antibodies in patients from Malaysia with systemic lupus erythematosus

Article Abstract:

Rheumatic diseases like systemic lupus erythematosus (SLE) are characterized by elevated blood levels of autoantibodies, which recognize and attack the body's own molecules. One particular molecule recognized by autoantibodies is cardiolipin, a phosphate-containing fatty compound which is present in the membranes that surround cells. Anti-cardiolipin antibodies (aCLs) in patients with SLE have been associated with thrombosis (clot formation), nervous system disease, miscarriage, and thrombocytopenia (low levels of platelets, which are important for blood clotting). It turns out that SLE is more often found in Malaysians of Chinese ancestry than in those with Malay or Indian ancestry. To determine whether there were differences in aCL levels in SLE patients of different ethnic heritage, blood concentrations of aCL were measured in 200 patients (174 female) of whom 164 were Chinese, 26 Malay, and 10 Indian. The results were compared with those from 103 healthy subjects. Of 114 patients from whom medical details were available, joint and skin involvement was present in 95 percent, while the kidney was involved in 71 percent, a relatively high amount. Raised aCL levels were present in 16.5 percent of patients. Levels significantly correlated with age in both patients and healthy subjects, and were inversely related to platelet levels. The prevalence of elevated aCL did not differ among ethnic groups, nor did levels relate to involvement of particular organs. The study indicates that elevated aCL and thrombosis occur infrequently in SLE patients in Malaysia. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Autoantibodies, Demographic aspects, Malaysia, Autoimmune diseases, Systemic lupus erythematosus

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Hepatic involvement in patients with human immunodeficiency virus infection: discrepancies between AIDS patients and those with earlier stages of infection

Article Abstract:

Liver disease develops in a high proportion of patients with AIDS, and is indicated by hepatomegaly (enlargement of the liver), abnormal liver chemistries (blood tests that reflect liver function), and histological (tissue) changes. The extent and type of hepatic (liver) involvement varies with early- and late-stage human immunodeficiency virus (HIV) disease. The effect of HIV, the agent that causes AIDS, on the severity and type of liver disease was assessed in 45 patients with AIDS and 61 HIV-positive patients without AIDS (nonAIDS cases). Liver chemistries were determined, and hepatitis A and B status was identified. Liver biopsies were obtained on a subset of the AIDS and nonAIDS cases. The nonAIDS group included a higher number of intravenous drug users than the AIDS group. Hepatitis was identified in 12 of 18 nonAIDS cases, but in only 4 of 34 AIDS cases. Histologic evidence of liver pathology, indicative of opportunistic infection or tumor, was found in 9 of 18 patients with AIDS. Tissue responses and reactions to certain pathogens (such as hepatitis) appeared to be milder in the AIDS group, compared with the nonAIDS HIV-positive patients. This is probably due to the impaired immune function associated with late-stage HIV disease; in other words, patients with 'later-stage' immunodeficiency are less able to mount an immune response to pathogens. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, Complications and side effects, Liver diseases, Immunodeficiency

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