A rapid method for quantitation of cell surface IgM by an enzyme-linked immunosorbent assay

A solid phase fluorescent immunoassay for the rapid detection of virus antigen or antibodies in fetuses infected with porcine parvovirus

A solid phase fluorescent immunoassay using polyacrylamide beads coated with rabbit anti-porcine parvovirus antibodies has been developed and utilized in the diagnosis of porcine parvovirus infection. The antibody-coated beads (immunobeads) were used both to detect virus in mummified fetal tissues and to demonstrate specific antibodies in serum and ovarian follicular fluid. The immunobeads assay (IBA) was as sensitive as ELISA but more sensitive than virus isolation using tissue culture and haemagglutination tests. Both mummified and normal fetuses were obtained after experimental infection of SPF pregnant gilts. Using immunobeads, porcine parvovirus antigen was found in all mummified fetuses, but was found in only 1 out of 17 normal fetuses.

Pneumococcal cell wall phosphorylcholine elicits polyclonal antibody secretion in mice

Immunization of mice with phosphorylcholine (PC)-bearing Staphylococcus pneumoniae Type 2, strain 36a (R36a) results in both a PC-specific and a polyclonal increase in splenic plaque-forming cells. The polyclonal increase was observed in all strains tested, including those bearing an X-linked immune defect resulting in an undetectable anti-PC immune response. The magnitude of the polyclonal response is directly related to the amount of bacterial surface PC as detected by enzyme-linked immunosorbent assay. Congenitally athymic (nude) mice mount an anti-PC plaque-forming cell response after R36a immunization but fail to produce a significant polyclonal response. From our results it appears that PC on the cell wall of a bacterium acts both as a polyclonal activator and a specific antigen, stimulating each by different mechanisms.

Cellular enzyme-linked immunospecific assay (CELISA). IV. Inhibition of endogenous cellular alkaline phosphatase activity

The cellular enzyme-linked immunospecific assay (CELISA) uses ligands conjugated to calf intestinal alkaline phosphatase to quantitate antibody bound to antigens on the surfaces of whole cells. Since the endogenous alkaline phosphatase present in many cell types contributes unwanted background noise to the assay, ways of inhibiting endogenous cellular alkaline phosphatase were investigated. We found that the endogenous alkaline phosphatase in human peripheral blood mononuclear cells was incompletely inhibited by EDTA or L-cysteine. Levamisole, however, inhibited endogenous cellular alkaline phosphatase completely without impairing the sensitivity of the CELISA. The use of levamisole is recommended for assays that use alkaline phosphatase conjugates to detect molecules on the surfaces of cells that also contain endogenous alkaline phosphatase.

Sera used for complement-mediated cytolysis can alter B cell function in vitro

Nonspecific effects of reagents used to selectively isolate lymphocyte subpopulations are most often analyzed according to their influence on cell viability and proliferation. While characterizing monoclonal anti-human B cell antibodies, we detected consistent changes in B cell function between individual donors, no matter which antibody was employed to deplete B cell subpopulations. The source of these alterations was traced to the commercial complement-containing sera used for cytolysis. Different lots of serum from 3 separate commercial vendors and 2 animal species (rabbit and guinea pig) routinely altered B lymphocyte differentiation after stimulation with either pokeweed mitogen or Staphylococcus aureus (Cowan I), while cell viability, lymphocyte subpopulation distribution, and proliferative responses were unaffected.