Predictive value of in vitro tests for the IgE-dependent and the IgE-independent anaphylactoid reactions to muscle relaxants.

Several aspects of in vitro tests for life-threatening anaphylactoid reactions (AR) to neuromuscular blockers (NMB, muscle relaxants) were addressed and highlighted. They include topics which have been under study in our centre in the past few years. Already available tests and newly developed ones were assessed for diagnostic and predictive value, as well as for usefulness in understanding of mechanism(s) of AR. The theoretical and practical aspects of radioallergosorbent tests (RAST) for antibodies to NMB (particularly IgE), their predictive value and their possible use in "screening" with the hope of preventing AR are discussed. Confirmatory tests after AR include plasma or serum histamine/methylhistamine, tryptase and possibly eosinophil cationic protein (ECP), all of which point to activation of mast cells, basophils, eosinophils and possibly other inflammatory cells. Future anesthetics after AR can be guided by measurement of the in vitro release of histamine, leukotrienes and possibly eosinophil cationic protein (ECP) and serum antibodies. Antibody studies (mainly IgE by RAST) are valuable for diagnosis and, together with other tests, can throw light on cross-reaction and further clarify the mechanisms of AR. In RAST (IgE)-negative cases of AR, which may be due to immune or nonimmune mechanisms, mediator release measurements are particularly useful. Lymphocyte stimulation tests may also be useful in such cases. RASTs cannot be advocated for general preoperative screening, as yet. Further development or selection of potentially "susceptible" subpopulations may improve the predictive value of these tests.