Homogeneity of antibody responses in tuberculosis patients

The goals of the present study were twofold: (i) to compare the repertoires of antigens in culture filtrates of in vitro-grown Mycobacterium tuberculosis that are recognized by antibodies from noncavitary and cavitary tuberculosis (TB) patients and (ii) to determine the extent of variation that exists between the antigen profiles recognized by individual TB patients. Lipoarabinomannan-free culture filtrate proteins of M. tuberculosis were fractionated by one-dimensional (1-D) and 2-D polyacrylamide gel electrophoresis, and the Western blots were probed with sera from non-human immunodeficiency virus (non-HIV)-infected cavitary and noncavitary TB patients and from HIV-infected, noncavitary TB patients. In contrast to earlier studies based on recombinant antigens of M. tuberculosis which suggested that antibody responses in TB patients were heterogeneous (K. Lyashchenko et al., 1998, Infect. Immun. 66:3936-3940, 1998), our studies with native culture filtrate proteins show that the antibody responses in TB patients show significant homogeneity in being directed against a well-defined subset of antigens. Thus, there is a well-defined subset of culture filtrate antigens that elicits antibodies during noncavitary and cavitary disease. In addition, another set of antigens is recognized primarily by cavitary TB patients. The mapping with individual patient sera presented here suggests that serodiagnostic tests based on the subset of antigens recognized during both noncavitary and cavitary TB will enhance the sensitivity of antibody detection in TB patients, especially in difficult-to-diagnose, smear-negative, noncavitary TB patients.

Elevated PLA2 activity in schizophrenics and other psychiatric patients

We measured serum phospholipase A2 (PLA2) activity in 39 schizophrenics, 26 psychiatric controls, and 26 normal controls using a radioenzymatic assay with phosphatidylcholine as precursor. Serum PLA2 activity was significantly higher in schizophrenics (p = 0.002) and other psychiatric (including substance abusing) patients (p = 0.032) than in normal controls. Enzyme activity did not differ between the schizophrenic patients and psychiatric controls. Fifty-one percent of the schizophrenics and 46% of psychiatric controls had PLA2 values above the highest value for normal controls. In the psychiatric control group higher than normal PLA2 activities were observed in all diagnostic categories, including major depression, bipolar disorder, posttraumatic stress disorder (PTSD), and substance abuse. In the context of others' findings of increased circulating PLA2 in infectious and inflammatory conditions, these increases must be viewed as disease nonspecific. The significance of these changes and their relationship to other acute-phase protein changes needs to be clarified in future research.