Cell-mediated immunity in leprosy and transfer of delayed hypersensitivity reactions

Immunological disturbance in West and Lennox-Gastaut syndromes

Cell-mediated and humoral immunity were investigated in 18 patients with West syndrome, 12 with Lennox-Gastaut syndrome and 19 healthy controls. The study included determination of T and B peripheral blood lymphocytes, serum levels of IgG, IgA and IgM, skin sensibilization with DNCB, intracutaneous PHA, leucocyte migration inhibition test and lymphocyte blastic transformation in the presence of PHA. Cell-mediated deficiency was detected in 28 children whereas low levels of immunoglobulins were observed only in 6 children. Immunological disturbances were more prominent in children with West syndrome.

Cell-mediated and humoral immunity in West syndrome

The immunological status of five children with West syndrome consequent to previous cerebral lesions was investigated. Three children had West syndrome and two were in transition from West to Lennox-Gastaut syndrome. All of them showed cellular immunological deficiencies in the following tests: sensitization to DNCB, intracutaneous reaction to PHA, inhibition of leucocyte migration, blastic transformation of lymphocytes, T and B lymphocytes in peripheric blood and levels of serum immunoglobulins. These immunological deficiencies, of different degrees of severity, were associated to frequent infections in these children. A possible association between the immunological deficiencies and autoimmunity is discussed.

Cellular antimicrobial immunity

Acquired resistance to infectious disease may be expressed by a predominantly humoral or a cellular mechanism or, more frequently, by a combination of the two. The cellular interactions which are responsible for the induction of the immune response in the skin, lung, intestinal mucosa, genitourinary tract, conjunctiva, and peritoneal cavity are discussed and the role of living or dead vaccines in the induction of acquired resistance is outlined. The host response involves three different cell types: the phagocytic cell (polymorphs or macrophages), the thymus-dependent (T) lymphocyte, and the thymus-independent (B) lymphocyte-plasma cell line. The normal unstimulated phagocytic cell is capable of killing most nonpathogenic bacteria that gain entry to the tissues. However, the presence of opsonic antibodies and activated macrophages is required to eliminate the pathogenic intracellular parasites. Such immunological activation involves the presence of sensitized T-lymphocytes in the lesion. The cellular response is also characterized by the simultaneous development of a state of delayed-type hypersensitivity (DTH), along with the antimicrobial CMI response. A rising humoral response normally develops subsequently. Killed bacterial cells (except when incorporated into Freund's complete adjuvant) induce the humoral response without the CMI reaction so that such vaccines are not able to fully protect the host against the naturally acquired disease. With the development of cell fractionation methods as well as the identification of distinctive cell surface markers, suspensions of B- and T-cells and macrophages can now be prepared for use in increasingly sophisticated transfer and reconstitution studies. The role of the different cell types in the expression of humoral and cellular immunity has been determined, and the effect of various immunopotentiating and immunosuppressive regimens on the immune system as a whole has been evaluated quantitatively. These studies have led to an appreciation of the role played by suppressor B- and T-cells in the interplay of both humoral and cellular components of the host defense system during the development of immune tolerance, desensitization, anergy, autoimmunity, and the expression of an anamnestic immune response following reinfection.

Cell-mediated immunity in patients with carcinoma: correlation between clinical stage and immunocompetence

Cell-mediated immunity (CMI) was evaluated in 82 patients with non-lymphoid tumors by in vivo and in vitro methods. These included skin test with ubiquitous antigens, 2,4 dinitrochlorobenzene (DNCB) sensitization, determination of T and B peripheral blood lymphocytes, and lymphocyte response to phytohemagglutinin (PHA). The patients were divided into two groups: those with localized and those with disseminated disease (LD and DD). The patients with LD showed no significant differences in CMI when compared with normal controls. The patients with DD showed various defects in CMI when compared with controls and patients with LD. There were significant differences in the response to DNCB, and streptokinase-streptodornase (SK-SD) was the most discriminative of the skin-test antigens. The response to PHA was greatly depressed in patients with DD, whether in the presence of autologous or homologous plasma; in some patients a factor inhibiting to blastogenesis was detected in the serum. In patients with DD, a T-cell lymphopenia was observed. These data showed a correlation between immunocompetence and clinical stage.

The immune system of the nine-banded armadillo (Dasypus novemcinctus, Linn)

The armadillo is rapidly emerging as an animal for biomedical research. A morphological study of the immune system of the armadillo was undertaken to try to demonstrate a possible defect in the morphogenesis of the lymphoid organs that could account for their susceptibility to leprosy. Blood from 20 domesticated adult armadillos revealed lymphocytes predominated among circulating leukocytes in the majority of animals, whereas in wild animals neutrophils predominated. Necropsies revealed well-developed thymus glands and the thymus-dependent areas in lymph nodes and spleens contained abundant lymphoid cells. Hence, we conclude that the susceptibility of the armadillo to leprosy cannot be explained on a morphological basis.