Henry F. Pabst

Cutting Edge: Defective NK Cell Activation in X-Linked Lymphoproliferative Disease

X-linked lymphoproliferative disease (XLP) is characterized by a selective immune deficiency to EBV. The molecular basis of XLP has been attributed to mutations of signaling lymphocytic activation molecule-associated protein, an intracellular molecule known to associate with the lymphocyte-activating surface receptors SLAM and 2B4. We have identified a single nucleotide mutation in SLAM-associated protein that affects the NK cell function of males carrying the mutated gene. In contrast to normal controls, both NK and lymphokine-activated killer cell cytotoxicity was significantly reduced in two XLP patients. In addition to decreased baseline cytotoxicity, ligation of 2B4 significantly augmented NK lytic function in normal controls but failed to enhance the cytotoxicity of NK cells from XLP patients. These findings suggest that association of SAP with 2B4 is necessary for optimal NK/lymphokine-activated killer cytotoxicity and imply that alterations in SAP/2B4 signaling contribute to the immune dysfunction observed in XLP.

Cerebellar hypoplasia and frontal lobe cognitive deficits in disorders of early childhood.

A developmental chronometry hypothesis of early brain damage is suggested in which regions of the brain with a protracted course of postnatal development will be more vulnerable than earlier maturing areas to deleterious effects of early insult and, therefore, may become common sites of abnormality across many disorders originating in early childhood. Initial investigations of the cerebellum and frontal lobes are presented using MRI and neuropsychological measures. Planimetric measures of the cerebellar vermis (lobuli I-V and VI-VII) and pons, and neuropsychological frontal lobe measures were obtained from high functioning individuals with autism (A), survivors of acute lymphoblastic leukemia (ALL) with brain sequelae following radiation and chemotherapy, and from rigorously selected healthy controls (C). The neuropsychological results were clustered according to functions commonly related to frontal brain, posterior brain, and left and right hemispheres. The A and ALL groups, as compared to C, yielded modest but consistently reduced MRI measures for vermal lobuli I-V and VI-VII. Hypoplasia of lobuli VI-VII was more marked than I-V. Performance on neuropsychological tests for frontal lobe functions was generally depressed in both groups, with more severe deficits in A. Between-group differences in verbal, visual-spatial, and emotional-social skills are discussed. The cerebellar and frontal brain deficits that are present in both clinical groups (A and ALL) may be common to other developmental and acquired disorders of early childhood. Such joint manifestation of cerebellar and frontal lobe abnormalities is in agreement with the concept of cerebellar significance for the development of higher cognitive functions.

Reduced measles immunity in infants in a well-vaccinated population

The recommended age for measles vaccination is based in part on information gathered when most mothers had natural measles. Nowadays many mothers have received measles vaccine. To assess this change measles antibody neutralization titers (NT) were determined for 278 mother-infant pairs. One hundred sixty-four mothers, born before 1958, likely had had natural measles (Group 1). Sixty mothers received one to three killed plus one attenuated measles vaccination (Group 2) and 54 received 1 attenuated measles vaccination only (Group 3). NT were determined for the mother and for the infant at birth and in the infant during the fourth and sixth months. Group 1 mothers and infants at every age had higher geometric mean NT than those in Groups 2 or 3 (P less than 0.05). By 7 months 65% of Group 1 infants and greater than 90% of Group 2 and 3 infants had an NT less than 1:10. The rate of antibody decay was significantly faster for Group 1 infants (P less than 0.05). Earlier vaccination in the infant should be considered.

Bone marrow transplantation for T − B − severe combined immunodeficiency disease in Athabascan-speaking native Americans

A distinct form of autosomal recessive T−B− severe combined immunodeficiency disease occurs with a high frequency among Athabascan-speaking Native Americans (SCIDA), including Navajo and Apache Indians from the southwestern US and Dene Indians from the Canadian Northwest Territories. The SCIDA gene has been linked to markers on chromosome 10p although its identity and role in the pathogenesis of this disease are unknown. We report our experience in treating 18 Navajo and Dene children with SCIDA between 1984 and 1999; 16 underwent bone marrow transplants (BMT). All children were symptomatic within 2 months of birth, had the T−B−NK+SCID phenotype and 67% presented with oral and/or genital ulcers. Three children had evidence of maternal engraftment prior to transplant. Two children died shortly after diagnosis. Three children required more than one BMT and 12 are alive with T cell reconstitution at a median follow-up of 7 years. Three children developed normal B cell immunity, two of whom received ablative conditioning therapy with either radiation or busulfan. Three of the four children who died received therapy with either radiation or busulfan and two of eight long-term survivors who were also recipients of cytotoxic chemotherapy have failed to develop secondary teeth. These results demonstrate the efficacy of BMT in treating infants with this distinct form of SCID, although B cell reconstitution remains a problem even with HLA-matched donors. Without conditioning, T cell engraftment is likely when closely HLA-matched donors are used. With T cell depletion of haplocompatible marrow, conditioning with immunosuppressive therapy may be necessary; however, children with SCIDA who were treated with intensive immunosuppressive and myeloablative therapy had a poor outcome. Bone Marrow Transplantation (2001) 27, 703–709.

Kinetics of immunologic responses after primary MMR vaccination

To study the kinetics of humoral as well as cellular immunity to measles and to test for associated immunosuppression 124 12 month old children were studied twice, before routine MMR and either 14, 22, 30, or 38 days after vaccination. Plaque reduction neutralization (PRN) titres were determined at these time points and lymphocytes were evaluated to identify changes in proportions of phenotype, their capacity to generate cytokines and to respond to blast transformation (BT) to measles hemagglutinin (HA), tetanus toxoid and Candida antigen. The PRN titre and BT to HA plateaued at 30 days and CD8+ and NK cells increased after immunization. Interleukin 2, 4, and 10 showed no significant changes. There was mild suppression of BT at 14 and 22 days post-immunization Interferon-gamma was the principal cytokine produced after primary measles immunization, suggesting primary measles immunization induces predominantly a TH1 type response.

Haploidentical Bone Marrow Transplantation for Severe Combined Immunodeficiency Disease Using Soybean Agglutinin-Negative, T-Depleted Marrow Cells

The major limitation of mismatched bone marrow transplantation is fatal graft versus host disease (GVHD). We processed haplotype-identical parental marrow with soybean agglutinin (SBA), sheep erythrocytes (SRBC), and neur-aminidase-treated SRBC (N-SRBC) to enrich for marrow stem cells and remove mature T cells. Nine patients with severe combined immunodeficiency disease (SCID) who lacked histocompatible donors received these SBA-negative, SRBC-negative, N-SRBC-negative marrow transplants (0.5–5.0 × 108 cells/kg). Seven of the nine patients (78%) had documented T-lymphocyte engraftment based on HLA typing and/or chromosomal analysis. Six patients showed evidence of B-cell immunity on the basis of increased immunoglobulin levels, isohemagglutinins, and/or HLA-DR typing of non-T cells. Three patients received marrow ablative chemotherapy pretransplant for maternal-fetal GVHD; neutrophil engraftment occurred between 9 and 17 days posttransplantation, erythrocytes engrafted within 3–4 weeks of transplantation, and platelet recovery was seen between day 17 and day 49 following the transplants. No immunosuppression was given prophylactically posttransplant. Three patients had no GVHD, two had transient rash and/or fever, and two developed mild focal (stage I) chronic cutaneous GVHD. Of the seven who engrafted, five (71%) are alive and clinically well without GVHD 18–35 months posttransplant. These data demon-strate that SBA- and SRBC/N-SRBC-treated haploidentical marrow transplantation results in functional lymphocyte engraftment in SCID without significant GVHD, and can be used for some patients who otherwise would have no hope for survival.

Cell-mediated and antibody immune responses to AIK-C and Connaught monovalent measles vaccine given to 6 month old infants

Measles vaccination of infants younger than 1 year of age should be successful in populations with a high proportion of measles vaccinated mothers. Infants whose mothers were vaccinated are born with less maternal antibody which can interfere with vaccination compared with infants whose mothers had measles. AIK-C or Connaught (CLL) measles vaccine was given to 300 6 month infants born to mothers who had measles (group 1) or who were vaccinated against measles (group 2). Pre- and post-vaccination measles antibody was measured by EIA and PRN and cell mediated immunity (CMI) by blast transformation and production of interferon-gamma and interleukin-10. After vaccination, mean antibody level, seroconversion and blastogenesis were significantly lower for group 1 than group 2 (p < 0.05). Post-vaccination measles IgG was significantly higher for group 2 CLL vaccinees compared with group 2 AIK-C (p < 0.05); seroconversion rates were 73 and 63%, respectively. More than 93% of group 2 infants had elevated measles IgG after vaccination. About 89% of all children had some evidence of a blastogenic response. Lymphoproliferation correlated strongly with cytokine production and weakly with IgG. Not all seroresponders had a CMI response and vice versa. AIK-C and CLL vaccines induce strong measles specific T and B immunity in most 6 month infants of vaccinated mothers.

Transfer factor in rat coccidiosis

Abstract An animal model for the evaluation of dialyzable transfer factor (TF) is described. Immunity against the intracellular intestinal protozoal parasite Eimeria nieschulzi was transferred to normal rats with TF made from lymphoid tissues of immune rats. Eimeria oocyst excretion in the feces was used as a measure of immunity. The reduction of oocyst excretion by animals given TF 48 hr before primary infection was highly significant, when compared with control groups. Animals treated with TF before the primary challenge were completely immune to a second challenge of the parasite. This model may be used to evaluate further the mechanism of TF.

The gene for severe combined immunodeficiency disease in Athabascan-speaking Native Americans is located on chromosome 10p.

Severe combined immunodeficiency disease (SCID) consists of a group of heterogeneous genetic disorders. The most severe phenotype, T-B- SCID, is inherited as an autosomal recessive trait and is characterized by a profound deficiency of both T cell and B cell immunity. There is a uniquely high frequency of T-B- SCID among Athabascan-speaking Native Americans (A-SCID). To localize the A-SCID gene, we conducted a genomewide search, using linkage analysis of approximately 300 microsatellite markers in 14 affected Athabascan-speaking Native American families. We obtained conclusive evidence for linkage of the A-SCID locus to markers on chromosome 10p. The maximum pairwise LOD scores 4.53 and 4.60 were obtained from two adjacent markers, D10S191 and D10S1653, respectively, at a recombination fraction of straight theta=.00. Recombination events placed the gene in an interval of approximately 6.5 cM flanked by D10S1664 and D10S674. Multipoint analysis positioned the gene for the A-SCID phenotype between D10S191 and D10S1653, with a peak LOD score of 5.10 at D10S191. Strong linkage disequilibrium was found in five linked markers spanning approximately 6.5 cM in the candidate region, suggesting a founder effect with an ancestral mutation that occurred sometime before 1300 A.D.

Measles vaccination of infants in a well-vaccinated population.

During outbreaks of measles, measles vaccine is recommended for infants considered to be at risk who are 6 months of age and older. In a prospective trial the serologic response to early measles immunization has been evaluated in 125 infants given monovalent measles vaccine at 6 to 8.5 months of age and measles‐mumps‐rubella at 15 months. The response to vaccination was measured by plaque reduction neutralization (PRN) assay and enzyme immunoassay. Infants were grouped by the mothers immunization history: natural immunity (n = 60, Group 1); killed followed by live, further attenuated vaccine (n = 22, Group 2); and live, further attenuated vaccine only (n = 43, Group 3). The prevaccination geometric mean titer (GMT) by PRN for Group 1 (GMT = 69) was significantly higher than that of Group 2 (GMT = 18) or 3 (GMT = 13). Seroconversion (4‐fold increase in PRN titer) rates after monovalent vaccine were 31,71 and 76% for Groups 1,2 and 3, respectively. Seroconversion percentages were higher when measured 6 to 8 weeks after vaccination compared with 4 to 5 weeks. After measles‐mumps‐rubella ≥97% of all infants had PRN titers >120 and were measles IgG‐positive by enzyme immunoassay. These data show that as demographics shift to a well‐vaccinated maternal population and susceptibility in younger infants, measles vaccination before the currently recommended age will be effective.