Cecilia Sepúlveda

Natural Killer Cell Activity in Patients With Septic Shock

ATURAL KILLER CELLS (NKC), a small subpopulation (approximately 8%) of lymphoid cells,’ which in vitro present a spontaneous ability to lyse transformed, virally infected, and some normal cells in a nonrestricted fashion, have been shown to play an important role in the immune surveillance against primary tumors and metastases.1-4 The high incidence of malignancy and the special susceptibility to viral infections shown by individuals with a selective and marked deficit in NKC function further stresses the importance of these cells as an in vivo defense system against disease.4,5 A number of endogenous mediators have been suggested to play a role in the etiology of septic shock.‘-* This heterogeneous condition, arising as a complication of septicemia, is accompanied by numerous pathophysiologic changes.’ Reports of a bactericidal response of NKC to direct contact with certain bacteria, either through a direct action or via the Iymphokineactivation of other immune cells,‘o91’ led us to examine NKC activity (NKCA) in a population of septic shock patients in critical conditions and compare it with values obtained from a group of normal volunteers.

A simple method for negative and positive selection of murine and human IgM-bearing lymphocytes based on the use of antibody-coated silica microparticles

The use of octadecyl silica microparticles is proposed as an alternative method for negative and positive selection of IgM-bearing lymphocytes. SiC18 microparticles coated with affinity purified IgG anti-IgM were evaluated in their efficiency to deplete IgM-bearing cells. 6 mg of SiC18-IgG depleted an average of 97% IgM-bearing cells from a murine spleen cell suspension and of 84% IgM-bearing cells from human spleen cells. The viability of the selected cells was not affected by this procedure. We also analyzed the ability of whole serum to release IgM-bearing cells from the complex SiC18-target cell. The IgM releasing efficiency was 98%, with a resulting viability of 85%. These results indicate that SiC18 microparticles, saturated with specific antibodies, may be used as an alternative method for depletion or purification of cells bearing the corresponding antigen, from complex cell suspensions. The method is simple, efficient and inexpensive, representing an interesting alternative to the immunomagnetic selection.

Frequency of CCR5 gene 32-basepair deletion in Chilean HIV-1 infected and non-infected individuals.

A 32-basepair deletion polymorphism in the CCR5 chemokine receptor gene (CCR5Delta32) has been identified and shown to have functional significance in determining susceptibility to infection by human immunodeficiency virus type 1 (HIV-1) and possibly in influencing disease progression in HIV-1 positive individuals. These findings led to an interest in studies of DeltaCCR5 allele geographical distribution in human population, for complete understanding of the role of CCR5 in HIV-1 epidemiology. Inter-population variation in CCR5Delta32 frequency may be a significant factor in the prediction of AIDS endemicity. In this report we assessed the frequency of DeltaCCR5 in a Chilean population (63 HIV-1 infected and 62 non-infected individuals). No homozygous CCR5Delta32 individual was identified, and no significant difference was observed between HIV-1 infected (3/63) and non-infected (3/62) individuals for the heterozygote CCR5Delta32 state. This is the first evidence of the contribution of DeltaCCR5 allele to the genetic background of the Chilean population, which is characterized by intense ethnic admixture and by gene flow from the European Spanish gene pool.

Enhancement of natural killer cell activity in HIV-1-infected subjects by a mixture of the calcium ionophore A23187 and the phorbol ester TPA: lack of response to a similar challenge with interleukin-2 or alpha-interferon.

When compared to controls (n = 30), human immunodeficiency virus type-1 (HIV-1)-positive individuals, either asymptomatic (n = 10) or diagnosed with acquired immunodeficiency syndrome (AIDS) (n = 10), showed a statistically significant decrease in the percentage and absolute number of CD4+ T-lymphocyte cells (flow cytometry, Becton Dickinson FACScan; mean ± SD of 42.6 ± 6.9 and 948.5 ± 393.3, 19.5 ± 8.7 and 269.8 ± 174.3, 4.6 ± 4.1 and 60.1 ± 134.3, respectively; Students t-test, p < 0.05). However, this decrease was less marked in asymptomatic patients; in fact, the percentage and number of the above cells in this group of subjects was significantly higher than in the AIDS patients (Students t-test, p < 0.05). However, we failed to find significant differences in the percentage of natural killer cells (NKCs; CD15+CD56+) between the HIV-1-infected asymptomatic or AIDS groups of patients, or when compared with the controls (mean ± SD of 10.4% ± 9.4%, 14.3% ± 9.7%, and 14.8% ± 6.4%, respectively). Whereas either group of patients had a lower number of NKCs per microliter than the control group (mean ± SD of 137.8 ± 87.6, 91.1 ± 98.3, and 331.5 ± 266.5, respectively), this decrease only reached statistical significance for the AIDS patients (Students t-test, p < 0.05). Healthy controls showed statistically significantly higher NKC activity than either the HIV-1-infected asymptomatic or AIDS group of patients (K-562 target cell; mean ± SD and range values as percentage of specific lysis of 19.1% ± 15.6% and 2.4%-58.2%, 3.4% ± 3.2% and less than 0.1% [non-detectable]-10.3%, and 6.4% ± 5.5% and less than 0.1%-19.5%, respectively; Students t-test, p < 0.05). Challenge of samples from the control group with either interleukin-2, α-interferon, or with a mixture of the calcium ionofore A23187 (Io) plus the 12-O-tetradecanoylphorbol-13-acetate ester (TPA) resulted in every case in a statistically significant increase in NKC lytic function (mean ± SD and range values as percentage of specific lysis of 19.1% ± 15.6% and 2.4%-58.2%, 27.6% ± 17.4% and less than 0.1%-56.0%, 32.1% ± 20.9% and 2.1%-76.4%, and 62.6% ± 24.0% and 16.7%-95.0%, respectively; Students t-test, p < 0.05). A similar challenge for samples from the HIV-1-positive subjects, either asymptomatic or with AIDS, resulted in most cases in an enhanced NKC activity; however, this increase in NKC lytic function reached statistical significance only for the group of Io + TPA-incubated samples (Students t-test, p < 0.05). These results indicate that control or patient baseline NKC activity, and the response of this cellular immune function to a challenge.

Immunological evaluation of patients with invasive carcinoma of the gallbladder

Forty-three patients with invasive adenocarcinoma of the gallbladder were postoperatively studied in order to determine their general immunological status as well as the local immunohistological reaction to the tumor. At the end of the follow-up, they formed two groups: 19 living patients (group GL) and 24 dead patients (group GD). As a control group (GC), 21 patients with cholecistectomy for cholelithiasis and without carcinoma were simultaneously evaluated. In GL, most of the tumors were limited to the gallbladder wall, and in GD, most of the tumors were already disseminated at the time of diagnosis. GD presented a lower percentage of peripheral blood B lymphocytes, as compared to GL and GC cases. Skin tests of delayed hypersensitivity were significantly more reactive in GL cases than in GD cases, and less reactive in GD than in GC cases. The immunohistological evaluation of the gallbladder yielded a lower B lymphocyte infiltration in GD tumors than in the control cases. GL cases showed a higher intratumoral lymphocytic and mononuclear cell infiltration than GD cases. Although the clinical stage was higher in GD than in GL cases, there were also significant differences in the local immune response and the general immunological status. Patients with invasive gallbladder adenocarcinoma showing longer postoperative survival revealed normal or increased local and general immunological reactions, whereas patients with disseminated tumors showed an important humoral and cellular secondary immunodeficiency.

Por primera vez en Chile una estudiante del sexo femenino

MEDICINA.-Memoria de prueba para optar al grado de Licenciado enla Facultad de Medicina i Farmacia, leida el 25 de diciembre de 1886 porla senorita Eloisa R. Diaz.