Summary:Anticardiolipin antibody levels were measured in 57 patients with Mycoplasma pneumoniae infection and 21 patients with other infections. Significantly more patients in the mycoplamsa group had increased IgM and IgG anticardiolipin. Within the mycoplasma group significantly higher titres were found in patients with severe infection (assessed by need for hospital admission) and in patients with cold agglutinins. A tendency for particularly high titres to occur in patients with extra-pulmonary complications was identified.

The probability of a patient with nut allergy having specific IgE to a particular combination of peanut, hazelnut and brazil nut is similar, whatever their age or sex. The apparent increase in multiple nut reactivity with increasing age may therefore be due to exposure of previously unchallenged sensitivity. The frequency of multiple-nut specificity is sufficiently high that patients should always be tested for allergy to a range on nuts if they have a history of reacting to any nut.

18 out of 34 patients with atopic dermatitis were shown to have 5–32% of their serum IgE present in a high molecular weight (HMW) form (470,000 daltons). There was no simple correlation between the amount of HMW and the total serum IgE. The HMW peak was not affected by freezing and thawing the serum, but the complexes could be split by lowering the pH of serum fractionation. Some patients were tested sequentially on different occasions and although their clinical status may have altered during this time, there was no marked alteration of the HMW fraction. Results are compared with patients with raised IgE due to parasitic infections. Anti-IgE antibodies have been demonstrated in the HMW fraction.

SUMMARYSerum levels of the soluble form of the low-affinity receptor for IgE (FcERII, CD23) (sCD23) are elevated in autoimmune conditions associated with hypergammaglobuhnaemia and B cell hyperactivity. Very high levels of sCD23 are found in patients with B-chronic lymphatic leukaemia (B-CLL) who are, however, frequently hypogammaglobulinaemic. We therefore compared the serum levels of sCD23 in healthy controls (« = 33) with three conditions associated with hypogammaglobulinaemia (HGG) and varying B cell numbers: X-linked agammaglobulinaemia (XLA, « = 12), common variable immunodeficiency (CVI, n = 20) and B-chronic lymphatic leukaemia (n = 33). Serum levels of sCD23 showed a significant correlation with the CDIQ"*" B cell count in both normals and patients with CVI (r = 0 65, P < 0 0001). Amongst the different clinical groups, serum levels of sCD23 were increased in the order XLA < CVI < normals < CLL (medians 2 5, 7 7, 111 and 540, respectively; P < 0 001 for all comparisons except CVI versus normals P < 0 03 in a one-tailed test). In the CVI group, serum sCD23 was lowest amongst four patients with low B cell numbers. There was no overlap in sCD23 between patients with XLA and this subgroup of CVI patients. Serum sCD23 is, therefore, derived predominantly from B cells, and is significantly related to the peripheral blood B cell count.

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