HIV isolation from cerebrospinal fluid in relation to immunological deficiency and neurological symptoms.

Human immunodeficiency virus (HIV) could be isolated from the cerebrospinal fluid (CSF) of the majority (62%) of 72 patients in various stages of HIV infection. This high rate of successful virus isolation was achieved only when the time from lumbar puncture to initiation of the cell cultures was short, i.e. not exceeding 5 h. The HIV isolation rates were equally high in patients with persistent generalized lymphadenopathy (PGL), AIDS-related complex (ARC) and AIDS. Although the HIV recovery rate was low in patients with normal immunological parameters it was not correlated with the degree of severity of the immunodeficiency in the other patients. Furthermore, the recovery rates were not significantly correlated to the duration of the infection. HIV was recovered as often from patients with neurological symptoms as from patients without such symptoms. These findings suggest that in the majority of patients there is central nervous system (CNS) involvement early in the course of HIV infection and that HIV replication in the CNS may occur in the absence of a pronounced systemic cellular immunodeficiency and frequently without causing overt neurological symptoms.

Complement activation by measles virus cytotoxic antibodies: alternative pathway C activation by hemagglutination-inhibition antibodies but classical activation by hemolysin antibodies.

Antibodies against measles virus hemagglutinating (HA particles and hemolysin were shown to activate C differently. HA antibodies of rabbit or human origin activated C via the alternative pathway in cytotoxicity against chronically measles-infected cells. This cytotoxicity was expressed in C-4 deficient guinea-pig C or in rabbit C in the presence of 3 mM EGTA (ethylene-glycol-tetraacetic-acid) but not in 3 mM EDTA (ethylene-diamine-tetraacetic-acid). In contrast, human hemolysin antibodies activated C only via the classical way. F (ab')2 fragments from rabbit or human anti-HA IgG antibodies were as efficient in C activation via the alternative pathways as intact IgG antibodies with a corresponding hemagglutination-inhibition titer.

Characterization of measles virus-specific cytotoxic antibodies by use of a chronically infected cell line.

The complement-dependent cytotoxic effects of measles virus specific antibodies on a chronically infected cell line were studied by a microcytotoxicity assay. Cell damage was determined by trypan blue staining. Monospecific antisera against the hemagglutinin (HA) and the hemolysin (HL) of the virus were both cytotoxic. Rabbits, immunized with measles virus, developed cytotoxic antibodies in parallel with the appearance of antibodies against the measles virus HA and HL. Human sera with high antibody titers against HA and HL also gave a specific cytotoxic reaction. The main part of the activity was carried by IgG in rabbit sera tested within 2 weeks after primary immunization and only IgM. The serum reaction was characterized by a prozone. The maximal degree of cytotoxicity varied between tests performed on different occasions. Complement, at higher concentrations than were used for analysis of antibody-mediated cytolysis, caused a significant lysis of infected cells. Cerebrospinal fluid (CSF) samples containing measles virus-specific antibodies were investigated. CSF from patients with subacute sclerosing panencephalitis displayed a pronounced cytotoxicity without a prozone. CSF samples from four patients with multiple sclerosis were identified by a specific cytotoxic reaction despite low titers of antibodies against HA and HL.