Defective MLR capacitation in the human: Low xenogeneic MLR capacity associated with HLA antigens AW25 B18, and DW2

HLA and T-lymphocyte function in old age

The role of the major histocompatibility complex in the genetic control of reactivity of peripheral blood mononuclear cells (T lymphocytes) to lectins and allogeneic cells as a function of age was investigated. In randomly selected aged subjects the frequencies of HLA-A, B, and some C locus alleles did not differ significantly from those in the control group. However, some tendencies of haplotype frequency differences between young and aged subjects were found. Significant associations of impaired or preserved T-lymphocyte function could be detected in connection with some HLA-A (A3, A11) antigens only. The tendency of some phenotypic HLA-A and B or C and B antigen associations to be in correlation with impaired or preserved T-lymphocyte reactivity in old age seemed to be independent of their age-related frequency differences. In family studies of a partially inbred Hungarian population, differences were found in the rate of diminution of allogeneic reactivity in groups sharing different HLA haplotypes. Based on statistical analysis of these data, a genetic factor segregating with the MHC and taking part in the regulation of the age-dependent decline of T-lymphocyte reactivity can be postulated.

Defective production of interferon-alpha associated with HLA-DW2 antigen in stable multiple sclerosis

Interferon (IFN) production by peripheral blood mononuclear cells after induction with one purified and three crude viral antigens was studied in 29 patients with stable multiple sclerosis (MS) and 29 healthy controls. Antiviral substance produced was characterized as interferon-alpha. MS patients produced significantly less IFN-alpha after induction with mumps and purified measles virus antigens and the same tendency was seen after induction with rubella virus antigen. However, when herpes simplex virus antigen was used as the stimulating agent, no difference was seen between MS patients and controls. The decreased ability to produce IFN-alpha was associated with the histocompatibility antigen Dw2. Control subjects positive for Dw2 also produced less IFN-alpha than Dw2-negative controls. In conclusion, we suggest that the observed impaired interferon-alpha production in MS is at least partially due to a high prevalence of Dw2 antigen in this disease.

Lymphocyte blast transformation responses and viral antibodies in relation to HLA antigens in multiple sclerosis

Fifty four clinically stable multiple sclerosis (MS) patients and 54 age- and sex-matched control subjects were HLA-typed, and their responses to herpes simplex, measles, mumps and rubella antigens were examined by the lymphocyte blast transformation test and by serum antibody titrations. Blast transformation response to purified tuberculin (PPD), mitogen phytohaemagglutinin (PHA), pokeweed mitogen (PWN) and concanavalin A (Con A) and spontaneous proliferation of lymphocytes were also studied. MS patients differed from controls by higher antibody levels to measles and rubella viruses and by lower specific blast transformation responses to rubella and measles antigens. When the relative strength of transformation responses was measured, mumps and herpes simplex responses were also lower in MS patients than in controls. In addition, spontaneous lymphocyte proliferation of MS patients in 6-day cultures was lower than that of control lymphocytes. In mitogen stimulations there were no differences between whole groups, but the oldest patients had lower responses to PHA and Con A than their matched controls. The frequency of HLA-Dw2 was 56.6% in MS patients and 32.1% in controls. The patients with and without Dw2 differed from each other only by a lower specific response to PPD in the Dw2-positive group. The immunological response of Dw2-positive controls resembled that of MS patients: low transformation response to viral antigens, low spontaneous proliferation and elevated measles antibodies. This finding supports the function of a genetically determined type of immune responsiveness with low cell-mediated immunity and high levels of certain viral antibodies as one susceptibility factor in multiple sclerosis.