No abstract

The segregation pattern of the phenotypes defined by the percentage of D8/17 positive cells within HLA-typed RF families are consistent with an autosomal recessive mode of inheritance not associated with the human MHC system. We postulate that these phenotypes indicate the presence of at least one necessary genetic factor for susceptibility to RF.

In a previous report (1), a family with C2 deficiency in the homozygous and the heterozygous states was described. The propositus was of special interest because the complete absence of C2 was associated with some manifestations of systemic lupus erythematosus. Further studies of this family included analysis of possible genetic linkage of the deficiency with known genetic markers. Determinations of HL-A antigens provided evidence that linkage with this system was present. Methods and MaterialsSerum samples were obtained from clotted blood, quickly frozen, and stored at -60°C. Samples were thawed once. C2 determinations were performed by both hemolytic titration and radial immunodiffusion (1). The heterozygous individuals were recognized by their level of C2 which was close to one half the normal.HL-A typing was done on lymphocytes isolated from the peripheral blood by Ficoll-Isopaque gradient centrifugation. A two-stage microtoxicity assay procedure was used. 120 typing sera were used and 28 antigens were typed for. The typing sera were obtained from the New York Blood Center and the Transplantation Immunology Branch Serum Bank of NIAID (2). Unidirectional mixed leukocyte cultures (MLC) were performed according to Hartzman et al. (3). Briefly, lymphocytes were isolated by Ficoll-Hypaque gradient centrifugation. 3 × 106 X-irradiated (3,000 rad) stimulating cells and 1.5 × 105 in 0.2 ml of RPMI 1640 medium supplemented with streptomycin, penicillin, and 20% heat-inactivated normal human serum were mixed in the wells of Falcon microtiter plates (Falcon Plastics, Div. of BioQuest, Oxnard, Calif.). Each culture was set up in triplicate. After 6 days of incubation at 37°C in 5% CO2 humidified atmosphere, 2 ~Ci of [SH]thymidine was added to each culture 16 h before harvesting. The lymphocytes were harvested and processed for liquid scintillation counting. Results and DiscussionThe pedigree of the S family is depicted in Fig. 1. The propositus, II2, is a woman with manifestations of systemic lupus erythematosus and homozygous for C2 deficiency. HL-A analysis also indicated homozygosity for HL-A10,W18. This was checked in two laboratories with different typing sera. To verify this further, unidirectional MLC were carried out using her cells as the stimulator and those of her daughter as the responder. It was clear that her daughter's leukocytes did

Clinical ragweed pollenosis (hay fever) and IgE antibody production specific for antigen E (the major purified protein antigen from ragweed pollen extract) correlated closely with HL-A haplotypes in successive generations of seven families. HL-A associated IgE antibody responsiveness was antigen specific and extended also to IgE antibody production. These data indicate an immune response (Ir) gene specific for antigen E necessary but not sufficient for the development of hay fever. This appears to be the first documentation of an Ir gene in man.