Variations of the lymphocytotoxicity test. An evaluation of sensitivity and specificity.

Multiple variations of the basic lymphocytotoxicity test have been reported to increase test sensitivity. Although these modifications are used routinely in crossmatch tests, as required by federal regulation, there has been no methodical assessment of the relative sensitivities and specificities of these techniques with the exception of the well-studied antiglobulin method. We have performed such a comparison and found that these modifications do not, uniformly, increase test sensitivity. We also observed that the effect of a technique modification on test sensitivity as measured by overall lymphocytotoxic antibody titer does not reflect, necessarily, the effect on HLA-specific antibody. It is widely believed that the antiglobulin method is the most sensitive of the lymphocytotoxicity techniques. We observed that while the antiglobulin method increased overall test sensitivity dramatically, we achieved a comparable level of sensitivity by either substituting B cells for T cells or doubling both the serum and the complement incubation times. However, no other technique modification detected as many HLA antibody specificities as did the antiglobulin method. The data presented here provide useful guidelines for selecting techniques for HLA typing, antibody screening, and cross-matching.

HLA-DR2 and narcolepsy.

Tissue typing was performed on 14 narcoleptics as defined by both strict sleep laboratory and clinical criteria. Six of these patients were blacks from North America, a race underrepresented in previous studies. All patients were HLA-DR2-antigen positive and had the same HLA-DR2 subtype. Clinical severity of disease was not correlated with HLA-DR2 heterozygosity or (putative) homozygosity. This study confirms that the extremely high association between HLA-DR2 and narcolepsy holds across comparisons of the three races studied to date when both clinical and sleep laboratory data are used. The presence or absence of HLA-DR2 in patients presenting with hypersomnolence may help support or exclude, respectively, a diagnosis of idiopathic narcolepsy.