Activation and effector functions of HMI

Size: px

Start display at page:

Download "Activation and effector functions of HMI"

Aubrey Parrish
8 years ago
Views:

1 Activation and effector functions of HMI Hathairat Thananchai, DPhil Department of Microbiology Faculty of Medicine Chiang Mai University 25 August 2015

2 ว ตถ ประสงค หล งจากช วโมงบรรยายน แล วน กศ กษาสามารถ อธ บายความแตกต างของ Thymus-dependent และ Thymusindependent antigen อธ บายความแตกต างของ primary และ secondary antibody response อธ บายข นตอนในการกระต น naïve B lymphocyte การสร างแอนต บอด รวมถ งกลไกการท างานของแอนต บอด อธ บายความหมาย การผล ต และประโยชน ของ monoclonal antibody

secondary antibody response อธ บายข นตอนในการกระต น naïve B lymphocyte การสร

3 Phases of the humoral immune response

4 Antigen recognition and antigen-induced B cell activation The activation of B cells requires antigen recognition in lymphoid tissues. Antigens enter secondary lymphoid organs through the blood or lymph and bind to the antigen receptor on specific B cells. The activation of antigen-specific B cells is initiated by the binding of antigen to membrane Ig molecules. BCR; B cell antigen receptor complex

Antigens enter secondary lymphoid organs through the blood or lymph and bind to the antigen

5 Signal transduction by BCR complex

6 Properties of Thymus-dependent and Thymus-independent antigens

7 Distinct B cell subsets mediates different types of antibody responses

8 A second signal is required for B-cell activation by either thymus-dependent or thymus-independent antigens

9 Role of CR2 and TLRs in B cell activation

10 T-B collaboration and the hapten-carrier effect There are three important characteristics of antihapten antibody responses to haptenprotein conjugate First, such responses require both hapten-specific B cells and protein (carrier)-specific T cells Second, to stimulate a response, the hapten and carrier portions have to be physically linked Third, the interaction is class II MHC restricted

hapten-specific B cells and protein (carrier)-specific T cells Second, to stimulate a response,

11 Routes of antigen entry Microbial antigens commonly enter through the skin and gastrointestinal and respiratory tracts. Antigens are captured by dendritic cells and transported to regional lymph nodes. Antigens that enter the blood stream are captured by antigenpresenting cells in the spleen.

Antigens are captured by dendritic cells and transported to regional

12 The sequence of events in T cell-dependent antibody production-1 1). Antigen is taken up by dendritic cells and presented to helper T cells. 2). Helper T cells are activeated and induced to express membrane proteins (CD40L) and cytokines. 3). Activated helper T cells are instructed to migrate toward the follicle. 4). B cells process and present antigen, and migrate toward the T cell zone.

Helper T cells are activeated and induced to express membrane proteins (CD40L) and cytokines. 3).

13 Migration of B cells and helper T cells and T-B interaction

14 Mechanisms of helper T cell-mediated B cell activation AID ; activation-induced deaminase

15 The sequence of events in T cell-dependent antibody production-2 5). T and B cells interact at the T-B interface, and B cells are activated by CD40L and cytokines.

16 The sequence of events in T cell-dependent antibody production-3 6). Small extrafollicular B cell foci form in the medulla cords of lymph nodes or between the periarteriolar lymphoid sheath and the red pulp of the spleen. B cells in these foci undergo low levels of isotype switching and somatic mutation and short-lived plasma cells that secrete antibodies.

periarteriolar lymphoid sheath and the red pulp of the spleen.

17 The sequence of events in T cell-dependent antibody production-4 7). Activated B cells migrate back into the follicle. Germinal centers form within the follicles. Affinity maturation, isotype switching, and the generation of memory B cells occur primarily in the germinal center of lymphoid follicle.

Germinal centers form within the follicles.

18 Germinal center reactions in T cell-dependent antibody responses Affinity maturation centroblasts T FH ; Follicular helper T cell

19 An overview of affinity maturation

20 Ig heavy chain isotype switching

21 The sequence of events in T cell-dependent antibody production-5 8). Long-lived plasma cells are generated from cells activated in the germinal center reaction, and some of these terminally differentiated plasma cells migrate to the bone marrow.

22 Sequence of events in humoral immune responses to T cell-dependent antigens

23 Primary and secondary humoral immune responses

24 The principle characteristics of primary and secondary antibody responses

25 The humoral immune response is mediated by antibody molecules that are secreted by plasma cells

26 Neutralization of microbes and toxins by antibodies

27 Neutralization of microbes and toxins by antibodies

28 The humoral immune response is mediated by antibody molecules that are secreted by plasma cells

29 Monoclonal Antibodies

31 Pathways of DNA synthesis DE NOVO PATHWAY Phosphoribosyl pyrophosphate + Uridylate Thymidine SALVAGE PATHWAY TK+ (thymidine kinase) Hypoxantine HGPRT+ (hypoxanthine guanine phosphoribosyl transferase) Aminopterin Nucleotides DNA

32 Inject mouse with protein X Generation of monoclonal antibodies Myeloma cells (HGPRT -,Ig - ) unable to grow in HAT Mix and fuse cells Transfer to HAT medium Mouse spleen cells; some cells (red) make antibody to X Ascites fluid Culture single cells in separate wells Expand positive clones Culture Test each well for antibody to protein X

33 Humanized antibody : mab encoded by a recombinant hybrid gene and composed of the antigen-binding sites from a murine mab suffix = omab suffix = umab suffix = ximab suffix = zumab

34 Applications of monoclonal antibody Identification of phenotypic markers unique to particular cell types Immunodiagnosis Tumor diagnosis and therapy Immunotherapy Functional analysis of cell surface and secreted molecules

35 Cluster of Differentiation (CD) A system used for the classification of monoclonal antibodies direct against leukocyte surface antigens. HLDA (Human Leukocyte Differentiation Antigens) Workshops evaluated and compared many of these antibodies. Cellular distribution Functional studies Epitope mapping Nomenclature : CD Recently, more than 350 CD molecules for human have been identified.

36 Immunoassay Sandwich ELISA Direct immunofluorescence

37 Monoclonal antibodies that recognized tumor-specific antigens have been used to help eliminate tumors.

39 T-cell receptor recognizes tumour cell Antibodies block inhibitory signal to PD-1 A separate therapy uses antibodies that bind PD-1L on the tumour cell PD-1L binds PD-1, inhibiting T-cell response Tumor cells avoid an immune response by binding PD-1 on the surface of T cells. Antibody therapies that block PD-1/PD-1L binding can reactivate the T cell s response to the tumor. Nature Biotechnology 2012 Aug;30(8);

HUMORAL IMMUNE RE- SPONSES: ACTIVATION OF B CELLS AND ANTIBODIES JASON CYSTER SECTION 13

SECTION 13 HUMORAL IMMUNE RE- SPONSES: ACTIVATION OF B CELLS AND ANTIBODIES CONTACT INFORMATION Jason Cyster, PhD (Email) READING Basic Immunology: Functions and Disorders of the Immune System. Abbas,