The Borrelia-specific interferon (IFN)- gamma and interleukin (IL)-4 responses of 113 patients and control subjects were analyzed using the sensitive enzyme-linked immunospot method. Cerebrospinal fluid (CSF) and blood samples were obtained, during the course of disease, from patients with chronic or nonchronic neuroborreliosis (NB) and from control subjects without NB. Blood samples were obtained from patients with Lyme skin manifestations and from healthy blood donors. Early increased secretion of Borrelia-specific IFN- gamma (P<.05) and subsequent up-regulation of IL-4 (P<.05) were detected in the CSF cells of patients with nonchronic NB. In contrast, persistent Borrelia-specific IFN- gamma responses were observed in the CSF cells of patients with chronic NB (P<.05). In patients with erythema migrans, increased IFN- gamma (P<.001) was observed in blood samples obtained early during the course of disease, whereas increased IL-4 (P<.05) was observed after clearance. On the contrary, patients with acrodermatitis chronica atrophicans had Borrelia-specific IFN- gamma (P<.001), but not IL-4, detected in blood samples. The present data suggest that an initial IFN- gamma response, followed by up-regulation of IL-4, is associated with nonchronic manifestations, whereas a persistent IFN- gamma response may lead to chronic Lyme borreliosis.

Lyme borreliosis (LB) is the most common vector-borne disease in Europe, with over 70% of the cases represented by the cutaneous form erythema migrans (EM).1 Several studies confirm that reinfections, i.e. new episodes of LB, can occur in humans.2-7 In a 5-year follow-up study of individuals diagnosed with EM and treated with antibiotics in southern Sweden, 31 out of 708 individuals were found to be reinfected, i.e. had one or several new EM that required a doctor's visit and treatment with antibiotics.3 Although women and men were tick-bitten to the same extent, 27 of these 31 individuals were women, and all of these women were older than 44 years.3 This observation could in part be explained by host immune mechanisms acting differently either in women compared with men, or in reinfected compared with single-infected individuals. Women are known to display different immune

IgA deficiency was found to be present in 2 of 117 (1.7%) of these subjects, a figure that is concordant with estimates of relative risk from large case-control studies in the Swedish population. These data are consistent with a multiplicative model for the 8.1 haplotype contribution to IgA deficiency and contrasts with prior studies, suggesting a much higher risk for 8.1 homozygosity. Using a dense single nucleotide polymorphism marker analysis of the MHC region in HLA B8, DR3, DQ2 homozygous individuals, we did not observe consistent differences between cases (n = 26) and controls (n = 24). Overall, our results do not support the hypothesis that IgA deficiency is associated with a distinct subgroup of 8.1 related haplotypes, but rather indicate that risk is conferred by the common 8.1 haplotype acting in multiplicative manner.

The clinical course and outcome of several infectious diseases are dependent on the type of immune response elicited against the pathogen. In adults with neuroborreliosis (NB), a type 1 response with high production of Borrelia-specific IFN-gamma, but no IL-4, has been reported. Since children have a more benign course of NB than adults, we wanted to investigate type 1 and type 2 responses in children with NB. Cerebrospinal fluid (CSF) and blood were collected from children during the acute stage of 'confirmed NB' (n = 34), 'possible NB' (n = 30) and 'non-NB' (n = 10). The number of Borrelia-specific IL-4- and IFN-gamma-secreting cells was measured by enzyme-linked immunospot assay. Borrelia-specific secretion of both IL-4 and IFN-gamma was increased in CSF in confirmed (P < 0.05) and possible (P < 0.01) NB, when compared with non-NB controls. Furthermore, children with NB had significantly higher Borrelia-specific IL-4 secretion in CSF than an adult reference material with NB (P < 0.05). There were no differences in cytokine secretion in relation to onset or recovery of neurological symptoms. Since IL-4 is known to down-regulate the pro-inflammatory and possibly harmful effects of prolonged IFN-gamma responses, the prominent IL-4 response observed in the central nervous system compartment might contribute to the more benign disease course seen in children with Lyme NB.